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Etter D, Büchel R, Patt T, Biggel M, Tasara T, Cernela N, Stevens MJA, Johler S. Nitrite stress increases staphylococcal enterotoxin C transcription and triggers the SigB regulon. FEMS Microbiol Lett 2022; 369:6650348. [PMID: 35883216 PMCID: PMC9348819 DOI: 10.1093/femsle/fnac059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/11/2022] [Accepted: 05/05/2022] [Indexed: 11/13/2022] Open
Abstract
Staphylococcal food poisoning is a common food intoxication caused by staphylococcal enterotoxins. While growth of Staphylococcus aureus is not inhibited by the meat curing agent nitrite, we hypothesize that nitrite has an influence on enterotoxin C (SEC) expression. We investigated the influence of 150 mg/L nitrite on SEC expression at mRNA and protein level in seven strains expressing different SEC variants. Additionally, regulatory knockout mutants (Δagr, ΔsarA, ΔsigB) of high SEC producing strain SAI48 were investigated at mRNA level. Our findings suggest that nitrite effectively increases sec mRNA transcription, but the effects on SEC protein expression are less pronounced. While Δagr mutants exhibited lower sec mRNA transcription levels than wt strains, this response was not stress specific. ΔsigB mutants displayed a nitrite stress specific response. WGS analysis of the strains revealed a defective agr element in one strain (SAI3). In this strain sec transcription and SEC protein synthesis was not affected by the mutation. Consequently, additional regulatory networks must be at play in SEC expression. Comparison of our findings about SEC with previous experiments on SEB and SED suggest that each SE can respond differently, and that the same stressor can trigger opposing responses in strains that express multiple toxins.
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Affiliation(s)
- Danai Etter
- Institute for Food Safety and Hygiene, University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.,Institute for Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 9, 8092 Zurich, Switzerland
| | - Ramona Büchel
- Institute for Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 9, 8092 Zurich, Switzerland
| | - Tabea Patt
- Institute for Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 9, 8092 Zurich, Switzerland
| | - Michael Biggel
- Institute for Food Safety and Hygiene, University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland
| | - Taurai Tasara
- Institute for Food Safety and Hygiene, University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland
| | - Nicole Cernela
- Institute for Food Safety and Hygiene, University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland
| | - Marc J A Stevens
- Institute for Food Safety and Hygiene, University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland
| | - Sophia Johler
- Institute for Food Safety and Hygiene, University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland
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Etter D, Ukowitz C, Eicher C, Tasara T, Johler S. Mild NaCl Stress Influences Staphylococcal Enterotoxin C Transcription in a Time-Dependent Manner and Reduces Protein Expression. Front Microbiol 2022; 13:820067. [PMID: 35516428 PMCID: PMC9062481 DOI: 10.3389/fmicb.2022.820067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 03/29/2022] [Indexed: 12/01/2022] Open
Abstract
Enterotoxins (SEs) produced by Staphylococcus aureus are the cause of serious food intoxications. Staphylococcal enterotoxin C (SEC) is one of the main contributors, as it is often highly expressed. S. aureus possesses a competitive growth advantage over accompanying bacterial flora under stress conditions encountered in foods, such as high NaCl concentrations. However, the influence of NaCl as an external stressor on SEC expression is still unclear. We investigated the influence of 4.5% NaCl on sec mRNA and SEC protein levels. A qRT-PCR assay revealed that NaCl stress leads to time-dependently decreased or elevated sec mRNA levels for most strains. SEC protein levels were generally decreased under NaCl stress. Our findings suggest that NaCl stress lowers overall SEC concentration and time-dependently affects sec mRNA levels.
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Affiliation(s)
- Danai Etter
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Zurich, Switzerland.,Laboratory of Food Microbiology, Institute for Food Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Christina Ukowitz
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
| | - Corinne Eicher
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
| | - Taurai Tasara
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
| | - Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
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Oliveira R, Pinho E, Almeida G, Azevedo NF, Almeida C. Prevalence and Diversity of Staphylococcus aureus and Staphylococcal Enterotoxins in Raw Milk From Northern Portugal. Front Microbiol 2022; 13:846653. [PMID: 35391724 PMCID: PMC8981150 DOI: 10.3389/fmicb.2022.846653] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 02/16/2022] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus and staphylococcal enterotoxins are a serious public health concern associated with hospital and community-acquired illnesses. Dairy animals frequently shed S. aureus into the milk supply which can lead to food poisoning in humans. This study aims to investigate the prevalence and genetic diversity of S. aureus and staphylococcal enterotoxins in raw milk from the main dairy region of mainland Portugal. S. aureus was found in 53.0% (95% CI: 40.6-65.4%) of 100 raw cow's milk samples collected from bulk cooling tanks. The highest contamination level was 3.4 log10 CFU.mL-1, and in some samples more than one S. aureus strain was identified. Staphylococcal enterotoxins (SEA-SEE) were detected in one sample. Spa typing revealed 62 distinct S. aureus isolates, being t529 (17.7%, 95% CI: 8.2-27.3%) and t1403 (16.1%, 95% CI: 7.0-25.3%) the predominant types, commonly associated with livestock infection or carriage. The antimicrobial susceptibility test showed that 35.5% of the S. aureus isolates were resistant to at least one antimicrobial agent, with resistance to penicillin being the highest (32.3%, 95% CI: 20.6-43.9%) followed by tetracycline (24.2%, 95% CI: 13.5-34.9%), ciprofloxacin (16.1%, 95% CI: 7.0-25.3%) and chloramphenicol (16.1%, 95% CI: 7.0-25.3%). Moreover, five isolates (8.1%, 95% CI: 1.3-14.8%) were identified as methicillin-resistant S. aureus (MRSA, cefoxitin resistant). Regarding virulence/resistance genes, 46,8% (95% CI: 34.4-59.2%) isolates harbored at least one enterotoxin-encoding gene, and the seg gene was the most frequently detected (41.9%, 95% CI: 29.7-54.2%) followed by the sei (40.3%, 95% CI: 28.1-52.5%), sec (6.5%, 95% CI: 0.3-12.6%), seh (4.8%, 95% CI: 0.0-10.2%), and sea (1.6%, 95% CI: 0.0-4.7%) genes. Five (8.1%, 95% CI: 1.3-14.8%) non-enterotoxigenic isolates carried the mecA gene (corresponding to isolates phenotypically classified as MRSA), and 4.8% (95% CI: 0.0-10.2%) enterotoxigenic strains also had the tsst-1 gene. Our study confirm that raw milk can be a zoonotic source of S. aureus, including enterotoxigenic and MRSA strains. Furthermore, the majority of enterotoxigenic isolates were found to contain genes encoding SEs (SEG, SEH and SEI) not routinely screened. This shows the need for a broader SE screening in food safety control, as well as the relevance of risk mitigation measures to control S. aureus transmission along the food chain in Portugal.
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Affiliation(s)
- Ricardo Oliveira
- I.P - National Institute for Agrarian and Veterinarian Research (INIAV), Vairão, Portugal.,Laboratory for Process Engineering, Environment, Biotechnology and Energy (LEPABE), Faculty of Engineering, University of Porto, Porto, Portugal.,Associate Laboratory in Chemical Engineering (ALiCE), Faculty of Engineering, University of Porto, Porto, Portugal
| | - Eva Pinho
- I.P - National Institute for Agrarian and Veterinarian Research (INIAV), Vairão, Portugal.,Laboratory for Process Engineering, Environment, Biotechnology and Energy (LEPABE), Faculty of Engineering, University of Porto, Porto, Portugal.,Associate Laboratory in Chemical Engineering (ALiCE), Faculty of Engineering, University of Porto, Porto, Portugal
| | - Gonçalo Almeida
- I.P - National Institute for Agrarian and Veterinarian Research (INIAV), Vairão, Portugal.,Center for Study in Animal Science (CECA), ICETA, University of Porto, Porto, Portugal
| | - Nuno F Azevedo
- Laboratory for Process Engineering, Environment, Biotechnology and Energy (LEPABE), Faculty of Engineering, University of Porto, Porto, Portugal.,Associate Laboratory in Chemical Engineering (ALiCE), Faculty of Engineering, University of Porto, Porto, Portugal
| | - Carina Almeida
- I.P - National Institute for Agrarian and Veterinarian Research (INIAV), Vairão, Portugal.,Laboratory for Process Engineering, Environment, Biotechnology and Energy (LEPABE), Faculty of Engineering, University of Porto, Porto, Portugal.,Associate Laboratory in Chemical Engineering (ALiCE), Faculty of Engineering, University of Porto, Porto, Portugal.,Centre of Biological Engineering (CEB), University of Minho, Braga, Portugal
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Mesbah A, Mashak Z, Abdolmaleki Z. A survey of prevalence and phenotypic and genotypic assessment of antibiotic resistance in Staphylococcus aureus bacteria isolated from ready-to-eat food samples collected from Tehran Province, Iran. Trop Med Health 2021; 49:81. [PMID: 34635183 PMCID: PMC8504009 DOI: 10.1186/s41182-021-00366-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 06/24/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Resistant Staphylococcus aureus (S. aureus) bacteria are considered among the major causes of foodborne diseases. This survey aims to assess genotypic and phenotypic profiles of antibiotic resistance in S. aureus bacteria isolated from ready-to-eat food samples. METHODS According to the previously reported prevalence of S. aureus in ready-to-eat food samples, a total of 415 ready-to-eat food samples were collected from Tehran province, Iran. S. aureus bacteria were identified using culture and biochemical tests. Besides, the phenotypic antibiotic resistance profile was determined by disk diffusion. In addition, the genotypic pattern of antibiotic resistance was determined using the PCR. RESULTS A total of 64 out of 415 (15.42%) ready-to-eat food samples were contaminated with S. aureus. Grilled mushrooms and salad olivieh harbored the highest contamination rate of (30%), while salami samples harbored the lowest contamination rate of 3.33%. In addition, S. aureus bacteria harbored the highest prevalence of resistance to penicillin (85.93%), tetracycline (85.93%), gentamicin (73.43%), erythromycin (53.12%), trimethoprim-sulfamethoxazole (51.56%), and ciprofloxacin (50%). However, all isolates were resistant to at least four antibiotic agents. Accordingly, the prevalence of tetK (70.31%), blaZ (64.06%), aacA-D (57.81%), gyrA (50%), and ermA (39.06%) was higher than that of other detected antibiotic resistance genes. Besides, AacA-D + blaZ (48.43%), tetK + blaZ (46.87%), aacA-D + tetK (39.06%), aacA-D + gyrA (20.31%), and ermA + blaZ (20.31%) were the most frequently identified combined genotypic patterns of antibiotic resistance. CONCLUSION Ready-to-eat food samples may be sources of resistant S. aureus, which pose a hygienic threat in case of their consumption. However, further investigations are required to identify additional epidemiological features of S. aureus in ready-to-eat foods.
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Affiliation(s)
- Arash Mesbah
- Faculty of Veterinary Medicine, Karaj Branch, Islamic Azad University, Karaj, Iran
| | - Zohreh Mashak
- Department of Food Hygiene, Karaj Branch, Islamic Azad University, Karaj, Iran.
| | - Zohreh Abdolmaleki
- Department of Pharmacology, Karaj Branch, Islamic Azad University, Karaj, Iran
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Etter D, Jenni C, Tasara T, Johler S. Mild Lactic Acid Stress Causes Strain-Dependent Reduction in SEC Protein Levels. Microorganisms 2021; 9:1014. [PMID: 34066749 PMCID: PMC8151770 DOI: 10.3390/microorganisms9051014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 12/12/2022] Open
Abstract
Staphylococcal enterotoxin C (SEC) is a major cause of staphylococcal food poisoning in humans and plays a role in bovine mastitis. Staphylococcus aureus (S. aureus) benefits from a competitive growth advantage under stress conditions encountered in foods such as a low pH. Therefore, understanding the role of stressors such as lactic acid on SEC production is of pivotal relevance to food safety. However, stress-dependent cues and their effects on enterotoxin expression are still poorly understood. In this study, we used human and animal strains harboring different SEC variants in order to evaluate the influence of mild lactic acid stress (pH 6.0) on SEC expression both on transcriptional and translational level. Although only a modest decrease in sec mRNA levels was observed under lactic acid stress, protein levels showed a significant decrease in SEC levels for some strains. These findings indicate that post-transcriptional modifications can act in SEC expression under lactic acid stress.
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Affiliation(s)
- Danai Etter
- Institute for Food Safety and Hygiene, University of Zurich, 8057 Zurich, Switzerland; (D.E.); (T.T.)
- Laboratory of Food Microbiology, Institute for Food, Nutrition and Health (IFNH), ETH Zurich, 8092 Zurich, Switzerland;
| | - Céline Jenni
- Laboratory of Food Microbiology, Institute for Food, Nutrition and Health (IFNH), ETH Zurich, 8092 Zurich, Switzerland;
| | - Taurai Tasara
- Institute for Food Safety and Hygiene, University of Zurich, 8057 Zurich, Switzerland; (D.E.); (T.T.)
| | - Sophia Johler
- Institute for Food Safety and Hygiene, University of Zurich, 8057 Zurich, Switzerland; (D.E.); (T.T.)
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Schmitt S, Stephan R, Huebschke E, Schaefle D, Merz A, Johler S. DNA microarray-based characterization and antimicrobial resistance phenotypes of clinical MRSA strains from animal hosts. J Vet Sci 2020; 21:e54. [PMID: 32735092 PMCID: PMC7402938 DOI: 10.4142/jvs.2020.21.e54] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 04/17/2020] [Accepted: 05/11/2020] [Indexed: 11/21/2022] Open
Abstract
Background Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of severe infections in humans and animals worldwide. Studies elucidating the population structure, staphylococcal cassette chromosome mec types, resistance phenotypes, and virulence gene profiles of animal-associated MRSA are needed to understand spread and transmission. Objectives The objective of this study was to determine 1) clonal complexes and spa types, 2) resistance phenotypes, and 3) virulence/resistance gene profiles of MRSA isolated from animals in Switzerland. Methods We analyzed 31 presumptive MRSA isolates collected from clinical infections in horses, dogs, cattle, sheep, and pigs, which had tested positive in the Staphaurex Latex Agglutination Test. The isolates were characterized by spa typing and DNA microarray profiling. In addition, we performed antimicrobial susceptibility testing using the VITEK 2 Compact system. Results Characterization of the 31 presumptive MRSA isolates revealed 3 methicillin-resistant Staphylococcus pseudintermedius isolates, which were able to grow on MRSA2 Brilliance agar. Of the 28 MRSA isolates, the majority was assigned to CC398 (86%), but CC8 (11%) and CC1 (4%) were also detected. The predominant spa type was t011 (n = 23), followed by t009 (n = 2), t034 (n = 1), t008 (n = 1), and t127 (n = 1). Conclusions The results of this study extend the current body of knowledge on the population structure, resistance phenotypes, and virulence and resistance gene profiles of MRSA from livestock and companion animals.
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Affiliation(s)
- Sarah Schmitt
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, 8057 Zurich, Switzerland
| | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, 8057 Zurich, Switzerland
| | - Ella Huebschke
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, 8057 Zurich, Switzerland
| | - Daniel Schaefle
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, 8057 Zurich, Switzerland
| | - Axel Merz
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, 8057 Zurich, Switzerland
| | - Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, 8057 Zurich, Switzerland.
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Chabi R, Momtaz H. Virulence factors and antibiotic resistance properties of the Staphylococcus epidermidis strains isolated from hospital infections in Ahvaz, Iran. Trop Med Health 2019; 47:56. [PMID: 31844416 PMCID: PMC6896349 DOI: 10.1186/s41182-019-0180-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 09/26/2019] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Resistant Staphylococcus epidermidis strains are considered to be one of the major causes of human clinical infections in hospitals. The present investigation was done to study the pattern of antibiotic resistance and the prevalence of virulence and antibiotic resistance genes amongst the S. epidermidis strains isolated from human hospital infections. METHODS One hundred hospital infectious samples were collected and S. epidermidis strains were identified using culture and biochemical tests. Isolated strains were subjected to disk diffusion and PCR. RESULTS Forty-six out of 100 hospital infectious samples (46%) were positive for S. epidermidis. S. epidermidis strains harbored the highest prevalence of resistance against penicillin (95.65%), tetracycline (91.30%), erythromycin (82.60%), cefazolin (78.26%), and trimethoprim-sulfamethoxazole (73.91%). All S. epidermidis strains had resistance against at least three different types of antibiotics, while the prevalence of resistance against more than seven types of antibiotics was 17.39%. AacA-D (69.56%), tetK (56.52%), mecA (45.65%), msrA (39.13%), and tetM (39.13%) were most commonly detected antibiotic resistance genes. The prevalence of vatC (4.34%), ermA (8.69%), vatA (8.69%), vatB (13.04%), ermC (13.04%), and linA (10.86%) were lower than other detected antibiotic resistance genes. ClfA (32.60%), agrIII (17.39%), and etB (13.04%) were the most commonly detected virulence factors. CONCLUSIONS The presence of virulent and multi-drug resistance S. epidermidis strains showed an important public health issue in hospitals.
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Affiliation(s)
- Roya Chabi
- Department of Microbiology, Shahrekord Branch, Islamic Azad University, PO. Box: 166, Shahrekord, Iran
| | - Hassan Momtaz
- Department of Microbiology, Shahrekord Branch, Islamic Azad University, PO. Box: 166, Shahrekord, Iran
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Morach M, Käppeli N, Hochreutener M, Johler S, Julmi J, Stephan R, Etter D. Microarray based genetic profiling of Staphylococcus aureus isolated from abattoir byproducts of pork origin. PLoS One 2019; 14:e0222036. [PMID: 31490990 PMCID: PMC6730867 DOI: 10.1371/journal.pone.0222036] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 08/20/2019] [Indexed: 12/22/2022] Open
Abstract
Many parts of pork meat processing are currently not used for human consumption in Switzerland, although they are of great nutritional value. Therefore, data on the occurrence of pathogenic organisms on byproducts is extremely scarce and the prevalence and population structure of Staphylococcus aureus on meat processing sidestreams is unknown. Hence, abattoir byproducts of pork origin including ear, forefoot, heart, intestine, liver, rib bone, sternum, bladder, stomach, hind foot and tongue originating from six abattoirs were screened for S. aureus. The obtained isolates were investigated by spa typing and DNA microarray analysis to reveal their genomic profile and population structure. The prevalence of S. aureus was generally low with a mean of 8%. In total, 40 S. aureus strains were detected and assigned to 12 spa types (t015, t1491, t1778, t091, t337, t899, t2922, t7439, t1333, t208, t4049, t034) and seven clonal complexes (CC1, CC7, CC9, CC30, CC45, CC49, CC398). Detected enterotoxin genes included sea, seb, sec, seh, sel and egc encoded toxin genes seg, sei, sem, sen, seo, and seu. None of the isolates harbored genes conferring methicillin resistance, but blaZ/I/R genes causing penicillin resistance were frequently found. In addition, strains from CC398 exhibited tetM and tetK, conferring tetracycline resistance. Similarity calculations based on microarray profiles revealed no association of clonal complexes with particular body parts, but revealed a certain correspondence of clonal complex and originating abattoir.
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Affiliation(s)
- Marina Morach
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Nadine Käppeli
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Mirjam Hochreutener
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Jérôme Julmi
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Danai Etter
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
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Dastmalchi Saei H, Safari E. Methicillin resistance and clonal diversity of Staphylococcus aureus isolated from nasal samples of healthy horses in Iran. ANN MICROBIOL 2019. [DOI: 10.1007/s13213-019-01484-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Käppeli N, Morach M, Corti S, Eicher C, Stephan R, Johler S. Staphylococcus aureus related to bovine mastitis in Switzerland: Clonal diversity, virulence gene profiles, and antimicrobial resistance of isolates collected throughout 2017. J Dairy Sci 2019; 102:3274-3281. [DOI: 10.3168/jds.2018-15317] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 12/23/2018] [Indexed: 11/19/2022]
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Sheet OH, Grabowski NT, Klein G, Reich F, Abdulmawjood A. Characterisation of mecA gene negative Staphylococcus aureus isolated from bovine mastitis milk from Northern Germany. Folia Microbiol (Praha) 2019; 64:845-855. [PMID: 30888635 DOI: 10.1007/s12223-019-00698-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 03/11/2019] [Indexed: 12/16/2022]
Abstract
Staphylococcus aureus (S. aureus) is an important causative agent of contagious intermammary infections in dairy cattle. S. aureus is also considered as an important foodborne pathogen and cause of food poisoning cases and outbreaks worldwide. In order to understand the molecular ecology of S. aureus, the present study compared phenotypic and genotypic characteristics of 70 S. aureus isolates from bovine mastitis milk samples collected during the period from August 2001 to March 2014 in different regions of Northern Germany. The S. aureus isolates were characterised phenotypically, as well as genotypically for their genetic diversity using multi-locus sequence typing (MLST), spa typing and the presence of virulence genes encoding 16 staphylococcal enterotoxins (sea-selu), toxic shock syndrome toxin (tst), thermonuclease (nuc), clumping factor (clfA and clfB), coagulase (coa) and the methicillin resistance gene mecA. A total of 16 sequence types were grouped into eight clonal complexes (CCs), and 17 spa types were identified. These included six novel sequence types and one novel spa type. The majority of bovine mastitis milk-associated sequence types belonged to the clonal complex CC5, CC97, CC133, and CC151 and showed closely related genotypes or lineages with sequence types of human origin. The genotype CC133 (ST133-t1403) was predominant, constituting 27.1% of the isolates. In addition, the S. aureus isolates displayed nine different enterotoxigenic profiles. All S. aureus were methicillin-susceptible (MSSA). The current study provides new information on phenotypic and genotypic traits of S. aureus isolates from bovine mastitis. The comparison of characteristics of isolates from the present study originating from mastitis milk showed similarities with human isolates. This might help to better understand the distribution of S. aureus in the one health context.
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Affiliation(s)
- O H Sheet
- Department of Veterinary Public Health, College of Veterinary Medicine, University of Mosul, Mosul, Iraq
| | - N T Grabowski
- Institute of Food Quality and Food Safety, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173, Hannover, Germany
| | - G Klein
- Institute of Food Quality and Food Safety, Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany
| | - F Reich
- Institute of Food Quality and Food Safety, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173, Hannover, Germany.,German Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589, Berlin, Germany
| | - A Abdulmawjood
- Institute of Food Quality and Food Safety, Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany.
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Abdolmaleki Z, Mashak Z, Safarpoor Dehkordi F. Phenotypic and genotypic characterization of antibiotic resistance in the methicillin-resistant Staphylococcus aureus strains isolated from hospital cockroaches. Antimicrob Resist Infect Control 2019; 8:54. [PMID: 30911380 PMCID: PMC6416839 DOI: 10.1186/s13756-019-0505-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 03/04/2019] [Indexed: 02/03/2023] Open
Abstract
Background Cockroaches are one of the most important and frequent insects responsible for harboring, transmission and dissemination of human pathogens in the hospital environment. The present research was done to study the phenotypic and genotypic characterization of antibiotic resistance in the Methicillin-resistant Staphylococcus aureus strains isolated from hospital cockroaches. Methods Five-hundred and thirty Periplanets americana and Blattella germanica cockroaches were collected and their gut content and external washing samples were subjected to bacterial isolation. MRSA strains were subjected to disk diffusion and PCR amplification of antibiotic resistance genes. Results Prevalence of MRSA strains in P. americana and B. germanica cockroaches were 52.77 and 43.33%, respectively. External washing samples of P. americana cockroaches had the highest prevalence of MRSA strains (59.57%). MRSA isolates of external washing samples harbored the highest prevalence of resistance against penicillin (100%), ceftaroline (100%), tetracycline (100%), gentamicin (83.33%) and trimethoprim-sulfamethoxazole (80.55%). MRSA strains isolated from gut content samples harbored the highest prevalence of resistance against penicillin (100%), ceftaroline (100%), tetracycline (100%), trimethoprim-sulfamethoxazole (80%) and gentamicin (73.33%). BlaZ, aacA-D, tetK, msrA, dfrA, ermA, gyrA, grlA and rpoB were the most commonly detected antibiotic resistance genes amongst the MRSA strains. Conclusions The present investigation is the first report of the phenotypic and genotypic evaluation of antibiotic resistance in the MRSA strains isolated from P. americana and B. germanica hospital cockroaches. Hospital cockroaches are considered as a potential mechanical vector for MRSA strains.
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Affiliation(s)
- Zohreh Abdolmaleki
- Department of Pharmacology, Faculty of Veterinary Medicine, Karaj Branch, Islamic Azad University, Karaj, Iran
| | - Zohreh Mashak
- Department of Food Hygiene, Faculty of Veterinary Medicine, Karaj Branch, Islamic Azad University, Karaj, Iran
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Hoekstra J, Rutten V, Sommeling L, van Werven T, Spaninks M, Duim B, Benedictus L, Koop G. High Production of LukMF' in Staphylococcus aureus Field Strains Is Associated with Clinical Bovine Mastitis. Toxins (Basel) 2018; 10:toxins10050200. [PMID: 29762488 PMCID: PMC5983256 DOI: 10.3390/toxins10050200] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/27/2018] [Accepted: 05/06/2018] [Indexed: 12/13/2022] Open
Abstract
Staphylococcus aureus, a major cause of bovine mastitis, produces a wide range of immune-evasion molecules. The bi-component leukocidin LukMF’ is a potent killer of bovine neutrophils in vitro. Since the role of LukMF’ in development of bovine mastitis has not been studied in natural infections, we aimed to clarify whether presence of the lukM-lukF’ genes and production levels of LukMF’ are associated with clinical severity of the disease. Staphylococcus aureus was isolated from mastitis milk samples (38 clinical and 17 subclinical cases) from 33 different farms. The lukM-lukF’ genes were present in 96% of the isolates. Remarkably, 22% of the lukM-lukF’-positive S. aureus isolates displayed a 10-fold higher in vitro LukMF’ production than the average of the lower-producing ones. These high producing isolates were cultured significantly more frequently from clinical than subclinical mastitis cases. Also, the detection of LukM protein in milk samples was significantly associated with clinical mastitis and high production in vitro. The high producing LukMF’ strains all belonged to the same genetic lineage, spa-type t543. Analysis of their global toxin gene regulators revealed a point mutation in the Repressor of toxins (rot) gene which results in a non-functional start codon, preventing translation of rot. This mutation was only identified in high LukMF’ producing isolates and not in low LukMF’ producing isolates. Since rot suppresses the expression of various toxins including leukocidins, this mutation is a possible explanation for increased LukMF’ production. Identification of high LukMF’ producing strains is of clinical relevance and can potentially be used as a prognostic marker for severity of mastitis.
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Affiliation(s)
- Jurriaan Hoekstra
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands.
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
| | - Victor Rutten
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands.
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
| | - Laura Sommeling
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands.
| | - Tine van Werven
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
- University Farm Animal Practice, 3481 LZ Harmelen, The Netherlands.
| | - Mirlin Spaninks
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
| | - Birgitta Duim
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands.
| | - Lindert Benedictus
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands.
- Division of Infection and Immunity, The Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK.
| | - Gerrit Koop
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
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Johler S, Macori G, Bellio A, Acutis PL, Gallina S, Decastelli L. Short communication: Characterization of Staphylococcus aureus isolated along the raw milk cheese production process in artisan dairies in Italy. J Dairy Sci 2018; 101:2915-2920. [PMID: 29397175 DOI: 10.3168/jds.2017-13815] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 12/09/2017] [Indexed: 11/19/2022]
Abstract
Staphylococcus aureus is a common cause of food-borne intoxications. Several staphylococcal food poisoning outbreaks have been linked to consumption of raw milk cheeses and artisanal cheese production. However, information on Staph. aureus isolated from artisanal raw milk cheeses and small-scale dairy production environments is very limited. Therefore, we aimed to characterize Staph. aureus isolated along the artisanal raw milk production chain by determining (1) the population structure, and (2) the presence/absence of enterotoxin genes, mecA/C, and pvl. We collected 276 samples from different production stages (raw milk, whey, curd, brine, drying worktops, and cheese) at 36 artisan dairies in Italy. A total of 102 samples from 25 dairies tested positive for Staph. aureus, with 80% positive samples among the tested artisan cheeses. All isolates were further characterized by spa typing and PCR screening for staphylococcal enterotoxin genes, the mecA/mecC genes characteristic for methicillin-resistant Staph. aureus, and the pvl gene encoding Panton-Valentine leukocidin. The 102 isolates represented 15 different spa types and were assigned to 32 different Staph. aureus strains. The spa type most frequently detected was t2953 (30%), which is associated with genotype B strains causing high within-herd levels of bovine mastitis. In addition, 3 novel spa types (t13269, t13277, and t13278) were identified. Although none of the strains harbored mecA/mecC or pvl, 55% of the isolates exhibited at least one enterotoxin gene. Many strains were present in samples from multiple dairies from different regions and years, highlighting the spread of Staph. aureus in small-scale cheese production plants. Our findings demonstrate that enterotoxigenic Staph. aureus and in particular t2953 (genotype B) isolates commonly occur in artisanal dairies and raw milk cheeses in Italy. It is particularly alarming that 80% of the artisan cheeses sampled in our study were positive for Staph. aureus. These findings stress the need for effective measures preventing staphylococcal food poisoning by limiting Staph. aureus growth and enterotoxin formation along the production chain and in the final product.
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Affiliation(s)
- S Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, 8057 Zurich, Switzerland
| | - G Macori
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, 10154 Torino, Italy.
| | - A Bellio
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, 10154 Torino, Italy
| | - P L Acutis
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, 10154 Torino, Italy
| | - S Gallina
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, 10154 Torino, Italy
| | - L Decastelli
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, 10154 Torino, Italy
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Ronco T, Klaas IC, Stegger M, Svennesen L, Astrup LB, Farre M, Pedersen K. Genomic investigation of Staphylococcus aureus isolates from bulk tank milk and dairy cows with clinical mastitis. Vet Microbiol 2018; 215:35-42. [PMID: 29426404 DOI: 10.1016/j.vetmic.2018.01.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/08/2018] [Accepted: 01/09/2018] [Indexed: 12/25/2022]
Abstract
Staphylococcus aureus is one of the most common pathogens that cause mastitis in dairy cows. Various subtypes, virulence genes and mobile genetic elements have been associated with isolates from bulk tank milk and clinical mastitis. So far, no Danish cattle associated S. aureus isolates have been whole-genome sequenced and further analyzed. Thus, the main objective was to investigate the population structure and genomic content of isolates from bulk tank milk and clinical mastitis, using whole-genome sequencing. This may reveal the origin of strains that cause clinical mastitis. S. aureus isolates from bulk tank milk (n = 94) and clinical mastitis (n = 63) were collected from 91 and 24 different farms, respectively and whole-genome sequenced. The genomic content was analyzed and a phylogenetic tree based on single nucleotide polymorphisms was constructed. In general, the isolates from both bulk tank milk and clinical mastitis were of similar genetic background. This suggests that dairy cows are natural carriers of the S. aureus subtypes that cause clinical mastitis if the right conditions are present and that a broad range of subtypes cause mastitis. A phylogenetic cluster that mostly consisted of ST151 isolates carried three mobile genetic elements that were primarily found in this group. The prevalence of resistance genes was generally low. However, the first ST398 methicillin resistant S. aureus isolate from a Danish dairy cow with clinical mastitis was detected.
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Affiliation(s)
- Troels Ronco
- National Veterinary Institute, Technical University of Denmark, Kemitorvet Build. 204, 2800 Kgs. Lyngby, Denmark.
| | - Ilka C Klaas
- Section for Production, Nutrition and Health, University of Copenhagen, Grønnegårdsvej 2, 1870 Fdr. C, Denmark
| | - Marc Stegger
- Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen S, Denmark
| | - Line Svennesen
- Section for Production, Nutrition and Health, University of Copenhagen, Grønnegårdsvej 2, 1870 Fdr. C, Denmark
| | - Lærke B Astrup
- National Veterinary Institute, Technical University of Denmark, Kemitorvet Build. 204, 2800 Kgs. Lyngby, Denmark
| | - Michael Farre
- SEGES Livestock Innovation, Agro Food Park 15, 8200 Aarhus N, Denmark
| | - Karl Pedersen
- National Veterinary Institute, Technical University of Denmark, Kemitorvet Build. 204, 2800 Kgs. Lyngby, Denmark
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Strommenger B, Layer F, Werner G. Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus in Workers in the Food Industry. STAPHYLOCOCCUS AUREUS 2018. [PMCID: PMC7150186 DOI: 10.1016/b978-0-12-809671-0.00009-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Staphylococcus aureus is part of the common flora on the skin and mucous membranes of mammals and approximately 20–30% of humans are persistently colonized, mainly by mostly susceptible human-adapted isolates. In contrast, colonization with methicillin-resistant S. aureus is rare (approximately 1%), predominantly transient and associated with prior contact to the health care system. Additionally, in recent years livestock-associated S. aureus clones contributed to colonization in humans, especially in those working in close contact to farm animals. A considerable percentage of colonizing S. aureus isolates is equipped with enterotoxin genes. Humans carrying enterotoxigenic isolates represent a contamination source when handling food, thus generating a continuous risk of S. aureus food intoxication. Molecular characterization of isolates colonizing humans and obtained from food, respectively, enables the tracing of food-related outbreaks back to the source of food intoxication. We will summarize current knowledge about the S. aureus population colonizing humans, including those in close contact to animals and food, respectively. Additionally, we will review data on the molecular characterization of S. aureus isolates related to staphylococcal foodborne disease and the elucidation of staphylococcal foodborne outbreaks. Staphylococcal food poisoning is a common foodborne disease, mediated by the ingestion of enterotoxins produced by enterotoxigenic strains of S. aureus. For several outbreaks of foodborne S. aureus disease, colonized personnel could be identified as the source of food contamination. However, because of the widespread occurrence of enterotoxigenic strains as human colonizers and the often transient nature of colonization, the source of contamination cannot always be identified unambiguously. Therefore, compliance with hygiene measures is the most important requirement to prevent food contamination by both human colonization and environmental S. aureus reservoirs.
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Safarpoor Dehkordi F, Gandomi H, Basti AA, Misaghi A, Rahimi E. Phenotypic and genotypic characterization of antibiotic resistance of methicillin-resistant Staphylococcus aureus isolated from hospital food. Antimicrob Resist Infect Control 2017; 6:104. [PMID: 29034091 PMCID: PMC5628482 DOI: 10.1186/s13756-017-0257-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/04/2017] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Pathogenic biotypes of the Methicillin-resistant Staphylococcus aureus (MRSA) strains are considered to be one of the major cause of food-borne diseases in hospitals. The present investigation was done to study the pattern of antibiotic resistance and prevalence of antibiotic resistance genes of different biotypes of the MRSA strains isolated from various types of hospital food samples. METHODS Four-hundred and eighty-five raw and cooked hospital food samples were cultured and MRSA strains were identified using the oxacillin and cefoxitin disk diffusion tests and mecA-based PCR amplification. Isolated strains were subjected to biotyping and their antibiotic resistance patterns were analyzed using the disk diffusion and PCR methods. RESULTS Prevalence of S. aureus and MRSA were 9.69 and 7.62%, respectively. Meat and chicken barbecues had the highest prevalence of MRSA. Prevalence of bovine, ovine, poultry and human-based biotypes in the MRSA strains were 8.10, 8.10, 32.43 and 48.64%, respectively. All of the MRSA strains recovered from soup, salad and rice samples were related to human-based biotypes. MRSA strains harbored the highest prevalence of resistance against penicillin (100%), ceftaroline (100%), tetracycline (100%), erythromycin (89.18%) and trimethoprim-sulfamethoxazole (83.78%). TetK (72.97%), ermA (72.97%), msrA (64.86%) and aacA-D (62.16%) were the most commonly detected antibiotic resistance genes. CONCLUSIONS Pattern of antibiotic resistance and also distribution of antibiotic resistance genes were related to the biotype of MRSA strains. Presence of multi-drug resistance and also simultaneous presence of several antibiotic resistance genes in some MRSA isolates showed an important public health issue Further researches are required to found additional epidemiological aspects of the MRSA strains in hospital food samples.
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Affiliation(s)
- Farhad Safarpoor Dehkordi
- Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
| | - Hasan Gandomi
- Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
| | - Afshin Akhondzadeh Basti
- Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
| | - Ali Misaghi
- Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
| | - Ebrahim Rahimi
- Department of Food Hygiene and Public Health, Faculty of Veterinary Medicine, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran
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Jans C, Merz A, Johler S, Younan M, Tanner SA, Kaindi DWM, Wangoh J, Bonfoh B, Meile L, Tasara T. East and West African milk products are reservoirs for human and livestock-associated Staphylococcus aureus. Food Microbiol 2017; 65:64-73. [PMID: 28400021 DOI: 10.1016/j.fm.2017.01.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/12/2017] [Accepted: 01/29/2017] [Indexed: 12/13/2022]
Abstract
Staphylococcus aureus frequently isolated from milk products in sub-Saharan Africa (SSA) is a major pathogen responsible for food intoxication, human and animal diseases. SSA hospital-derived strains are well studied but data on the population structure of foodborne S. aureus required to identify possible staphylococcal food poisoning sources is lacking. Therefore, the aim was to assess the population genetic structure, virulence and antibiotic resistance genes associated with milk-derived S. aureus isolates from Côte d'Ivoire, Kenya and Somalia through spa-typing, MLST, and DNA microarray analysis. Seventy milk S. aureus isolates from the three countries were assigned to 27 spa (7 new) and 23 (12 new) MLST sequence types. Milk-associated S. aureus of the three countries is genetically diverse comprising human and livestock-associated clonal complexes (CCs) predominated by the CC5 (n = 10) and CC30 (n = 9) isolates. Panton-Valentine leukocidin, toxic shock syndrome toxin and enterotoxin encoding genes were predominantly observed among human-associated CCs. Penicillin, fosfomycin and tetracycline, but not methicillin resistance genes were frequently detected. Our findings indicate that milk-associated S. aureus in SSA originates from human and animal sources alike highlighting the need for an overarching One Health approach to reduce S. aureus disease burdens through improving production processes, animal care and hygienic measures.
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Affiliation(s)
- Christoph Jans
- ETH Zurich, Institute of Food, Nutrition and Health, Laboratory of Food Biotechnology, LFV C22, Schmelzbergstrasse 7, 8092 Zurich, Switzerland
| | - Axel Merz
- University of Zurich, Institute of Food Safety and Hygiene, Winterthurerstrasse 272, 8057 Zurich, Switzerland
| | - Sophia Johler
- University of Zurich, Institute of Food Safety and Hygiene, Winterthurerstrasse 272, 8057 Zurich, Switzerland
| | - Mario Younan
- Vétérinaires Sans Frontières Germany, P.O. Box 25653, 00603 Nairobi, Kenya
| | - Sabine A Tanner
- ETH Zurich, Institute of Food, Nutrition and Health, Laboratory of Food Biotechnology, LFV C22, Schmelzbergstrasse 7, 8092 Zurich, Switzerland
| | - Dasel Wambua Mulwa Kaindi
- Department of Food Science, Nutrition and Technology, College of Agriculture and Veterinary Sciences, University of Nairobi, PO Box 29053, Nairobi, Kenya
| | - John Wangoh
- Department of Food Science, Nutrition and Technology, College of Agriculture and Veterinary Sciences, University of Nairobi, PO Box 29053, Nairobi, Kenya
| | - Bassirou Bonfoh
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire (CSRS), KM 17 route de Dabou, Adiopodoumé Yopougon, Abidjan - 01, B.P. 1303 Abidjan, Cote d'Ivoire
| | - Leo Meile
- ETH Zurich, Institute of Food, Nutrition and Health, Laboratory of Food Biotechnology, LFV C22, Schmelzbergstrasse 7, 8092 Zurich, Switzerland
| | - Taurai Tasara
- University of Zurich, Institute of Food Safety and Hygiene, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
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Johler S, Sihto HM, Macori G, Stephan R. Sequence Variability in Staphylococcal Enterotoxin Genes seb, sec, and sed. Toxins (Basel) 2016; 8:toxins8060169. [PMID: 27258311 PMCID: PMC4926136 DOI: 10.3390/toxins8060169] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 05/26/2016] [Accepted: 05/27/2016] [Indexed: 11/16/2022] Open
Abstract
Ingestion of staphylococcal enterotoxins preformed by Staphylococcus aureus in food leads to staphylococcal food poisoning, the most prevalent foodborne intoxication worldwide. There are five major staphylococcal enterotoxins: SEA, SEB, SEC, SED, and SEE. While variants of these toxins have been described and were linked to specific hosts or levels or enterotoxin production, data on sequence variation is still limited. In this study, we aim to extend the knowledge on promoter and gene variants of the major enterotoxins SEB, SEC, and SED. To this end, we determined seb, sec, and sed promoter and gene sequences of a well-characterized set of enterotoxigenic Staphylococcus aureus strains originating from foodborne outbreaks, human infections, human nasal colonization, rabbits, and cattle. New nucleotide sequence variants were detected for all three enterotoxins and a novel amino acid sequence variant of SED was detected in a strain associated with human nasal colonization. While the seb promoter and gene sequences exhibited a high degree of variability, the sec and sed promoter and gene were more conserved. Interestingly, a truncated variant of sed was detected in all tested sed harboring rabbit strains. The generated data represents a further step towards improved understanding of strain-specific differences in enterotoxin expression and host-specific variation in enterotoxin sequences.
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Affiliation(s)
- Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
| | - Henna-Maria Sihto
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
| | - Guerrino Macori
- National Reference Laboratory for Coagulase-Positive Staphylococci including Staphylococcus aureus, Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Via Bologna 148, 10154 Torino, Italy.
| | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
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Mossong J, Decruyenaere F, Moris G, Ragimbeau C, Olinger CM, Johler S, Perrin M, Hau P, Weicherding P. Investigation of a staphylococcal food poisoning outbreak combining case-control, traditional typing and whole genome sequencing methods, Luxembourg, June 2014. ACTA ACUST UNITED AC 2016; 20:30059. [PMID: 26608881 DOI: 10.2807/1560-7917.es.2015.20.45.30059] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 07/02/2015] [Indexed: 01/25/2023]
Abstract
In June 2014, a staphylococcal food poisoning outbreak occurred at an international equine sports event in Luxembourg requiring the hospitalisation of 31 persons. We conducted a microbiological investigation of patients and buffet items, a case-control study and a carriage study of catering staff. Isolates of Staphylococcus aureus from patients, food and catering staff were characterised and compared using traditional typing methods and whole genome sequencing. Genotypically identical strains (sequence type ST8, spa-type t024, MLVA-type 4698, enterotoxin A FRI100) were isolated in 10 patients, shiitake mushrooms, cured ham, and in three members of staff. The case-control study strongly suggested pasta salad with pesto as the vehicle of infection (p<0.001), but this food item could not be tested, because there were no leftovers. Additional enterotoxigenic strains genetically unrelated to the outbreak strain were found in four members of staff. Non-enterotoxigenic strains with livestock-associated sequence type ST398 were isolated from three food items and two members of staff. The main cause of the outbreak is likely to have been not maintaining the cold chain after food preparation. Whole genome sequencing resulted in phylogenetic clustering which concurred with traditional typing while simultaneously characterising virulence and resistance traits.
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Affiliation(s)
- Joël Mossong
- Laboratoire National de Santé, Dudelange, Luxembourg
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Johler S, Stephan R, Althaus D, Ehling-Schulz M, Grunert T. High-resolution subtyping of Staphylococcus aureus strains by means of Fourier-transform infrared spectroscopy. Syst Appl Microbiol 2016; 39:189-194. [PMID: 27021524 DOI: 10.1016/j.syapm.2016.03.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/28/2016] [Accepted: 03/03/2016] [Indexed: 10/22/2022]
Abstract
Staphylococcus aureus causes a variety of serious illnesses in humans and animals. Subtyping of S. aureus isolates plays a crucial role in epidemiological investigations. Metabolic fingerprinting by Fourier-transform infrared (FTIR) spectroscopy is commonly used to identify microbes at species as well as subspecies level. In this study, we aimed to assess the suitability of FTIR spectroscopy as a tool for S. aureus subtyping. To this end, we compared the subtyping performance of FTIR spectroscopy to other subtyping methods such as pulsed field gel electrophoresis (PFGE) and spa typing in a blinded experimental setup and investigated the ability of FTIR spectroscopy for identifying S. aureus clonal complexes (CC). A total of 70 S. aureus strains from human, animal, and food sources were selected, for which clonal complexes and a unique virulence and resistance gene pattern had been determined by DNA microarray analysis. FTIR spectral analysis resulted in high discriminatory power similar as obtained by spa typing and PFGE. High directional concordance was found between FTIR spectroscopy based subtypes and capsular polysaccharide expression detected by FTIR spectroscopy and the cap specific locus, reflecting strain specific expression of capsular polysaccharides and/or other surface glycopolymers, such as wall teichoic acid, peptidoglycane, and lipoteichoic acid. Supervised chemometrics showed only limited possibilities for differentiation of S. aureus CC by FTIR spectroscopy with the exception of CC45 and CC705. In conclusion, FTIR spectroscopy represents a valuable tool for S. aureus subtyping, which complements current molecular and proteomic strain typing.
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Affiliation(s)
- Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, CH-8057 Zurich, Switzerland
| | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, CH-8057 Zurich, Switzerland
| | - Denise Althaus
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, CH-8057 Zurich, Switzerland
| | - Monika Ehling-Schulz
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, AT-1210 Vienna, Austria
| | - Tom Grunert
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, AT-1210 Vienna, Austria.
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Merz A, Stephan R, Johler S. Staphylococcus aureus Isolates from Goat and Sheep Milk Seem to Be Closely Related and Differ from Isolates Detected from Bovine Milk. Front Microbiol 2016; 7:319. [PMID: 27014240 PMCID: PMC4789554 DOI: 10.3389/fmicb.2016.00319] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 02/29/2016] [Indexed: 11/13/2022] Open
Abstract
Dairy goat and sheep farms suffer severe economic losses due to intramammary infections, with Staphylococcus aureus representing the main cause of clinical mastitis in small ruminants. In addition, S. aureus contamination of goat and sheep milk may cause staphylococcal food poisoning, as many traditional caprine and ovine milk products are not subjected to pasteurization. Data on virulence and antimicrobial resistance genes, as well as on the clonality of S. aureus detected in goat and sheep milk is scarce. Therefore, it was the aim of this study to determine (i) spa types and clonal complexes (CC) and (ii) virulence and resistance gene profiles of S. aureus isolated from goat and sheep milk. A total of 162 milk samples from sheep and goats presenting signs of an intramammary infection and 104 bulk milk samples were collected. While low prevalence rates of S. aureus was detected on single animal level, 46% of the bulk tank milk samples from small ruminants were positive for S. aureus. All isolates were spa typed and CC and virulence and resistance gene patterns were determined using a DNA microarray. Data from 49 S. aureus isolates was included in the statistical analysis and the construction of a SplitsTree. The analyzed isolates could be assigned to eleven CC, with the large majority of goat and sheep isolates being assigned to CC130 and CC133. The findings of this study suggest that S. aureus shows pronounced adaptation to small ruminants in general, but not to sheep or goats in particular. Although some common characteristics among S. aureus from caprine, ovine, and bovine milk samples were observed, S. aureus from small ruminants seem to form a distinct population. As 67% of the detected S. aureus strains exhibited at least one enterotoxin gene, many caprine, or ovine raw milk products may be contaminated with low levels of enterotoxigenic S. aureus, stressing the importance of strict maintenance of the cold chain.
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Affiliation(s)
- Axel Merz
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich Zurich, Switzerland
| | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich Zurich, Switzerland
| | - Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich Zurich, Switzerland
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Lundberg Å, Nyman AK, Aspán A, Börjesson S, Unnerstad HE, Waller KP. Udder infections with Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus uberis at calving in dairy herds with suboptimal udder health. J Dairy Sci 2016; 99:2102-2117. [PMID: 26805990 DOI: 10.3168/jds.2015-9487] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 12/04/2015] [Indexed: 11/19/2022]
Abstract
Udder infections with Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus uberis are common causes of bovine mastitis. To study these pathogens in early lactation, a 12-mo longitudinal, observational study was carried out in 13 herds with suboptimal udder health. The aims of the study were to investigate the occurrence of these pathogens and to identify if presence of the 3 pathogens, and of genotypes within the pathogens, differed with respect to herd, season, and parity. Quarter milk samples, collected at calving and 4 d in milk (DIM), were cultured for the 3 pathogens. Genotyping of staphylococcal and streptococcal isolates was performed using spa typing and pulsed-field gel electrophoresis, respectively. For each of the 3 pathogens, cows with an udder infection at calving or 4 DIM were allocated to 1 of 4 infection types: cleared (pathogen present only at calving), persistent (pathogen present in the same quarter at calving and 4 DIM), new (pathogen present only at 4 DIM), or cleared/new (pathogen present in 1 quarter at calving and in another quarter at 4 DIM). Associations between season or parity and overall occurrence of pathogens or infection types were determined using univariable mixed-effect logistic-regression models and the Fisher's exact test, respectively. The most commonly occurring pathogen was Staph. aureus, followed by Strep. dysgalactiae and Strep. uberis. Persistent infections were the most common infection type among Staph. aureus-infected cows, whereas cleared infections were the most common among Strep. dysgalactiae- and Strep. uberis-positive cows. The proportion of cows with persistent Staph. aureus infections and the proportion of cows having a Strep. uberis infection at calving or 4 DIM were higher in the multiparous cows than in primiparous cows. Infections with Strep. dysgalactiae were less common during the early housing season than during the late housing or pasture seasons, whereas persistent Strep. uberis infections were less common during the pasture season than during the late housing season. The relative occurrence of the 3 pathogens, infection types of each pathogen, and genotype diversity of each pathogen throughout the year or in different seasons and parities varied among the herds, indicating that underlying factors predisposing for udder infections at calving differ between herds. Genotyping of bacterial isolates gave important insight into how such infection patterns differed within and between herds. These findings emphasize the need to choose preventive strategies for each individual herd.
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Affiliation(s)
- Å Lundberg
- Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, SE-751 89 Uppsala, Sweden; Department of Clinical Sciences, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
| | - A-K Nyman
- Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, SE-751 89 Uppsala, Sweden
| | - A Aspán
- Department of Bacteriology, National Veterinary Institute, SE-751 89 Uppsala, Sweden
| | - S Börjesson
- Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, SE-751 89 Uppsala, Sweden
| | - H Ericsson Unnerstad
- Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, SE-751 89 Uppsala, Sweden
| | - K Persson Waller
- Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, SE-751 89 Uppsala, Sweden; Department of Clinical Sciences, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
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Genotyping and DNA microarray based characterization of Staphylococcus aureus isolates from rabbit carcasses. Meat Sci 2015; 112:86-9. [PMID: 26555564 DOI: 10.1016/j.meatsci.2015.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 10/03/2015] [Accepted: 11/02/2015] [Indexed: 11/20/2022]
Abstract
Staphylococcus aureus can cause staphylococcal food poisoning. Although the organism is frequently detected on rabbit carcasses, little is known about the characteristics of S. aureus strains contaminating rabbit meat. In this study, 137 S. aureus isolates originating from 137 rabbit carcasses were spa typed and characterized by DNA microarray. The isolates were assigned to CC5, CC7, CC8, CC15, CC96, CC101, CC121, and ST890, and to 13 spa types (t056, t085, t091, t160, t179, t681, t741, t745, t1190, t1773, t4770, t8456, t14871). Enterotoxin genes detected included sea, sed, sej, and ser. In addition, the egc operon, encoding the newly described staphylococcal enterotoxins SEG/SEI/SElM/SElN/SElO/SElU, was found in all isolates except those of t091. While none of the examined isolates presented genes conferring methicillin, vancomycin, or aminoglycoside resistance, we frequently detected blaZ/I/R conferring resistance to penicillin. The isolates represented a heterogeneous group assigned to clonal lineages detected among humans and animals, with two spa types exclusively associated with rabbit meat (t4770, t8456).
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Fluorescence-based bioassays for the detection and evaluation of food materials. SENSORS 2015; 15:25831-67. [PMID: 26473869 PMCID: PMC4634490 DOI: 10.3390/s151025831] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 09/28/2015] [Accepted: 09/30/2015] [Indexed: 12/12/2022]
Abstract
We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based microarrays/biochips, such as antibody/protein microarrays, bead/suspension arrays, capillary/sensor arrays, DNA microarrays/polymerase chain reaction (PCR)-based arrays, glycan/lectin arrays, immunoassay/enzyme-linked immunosorbent assay (ELISA)-based arrays, microfluidic chips and tissue arrays, have been developed and used for the assessment of allergy/poisoning/toxicity, contamination and efficacy/mechanism, and quality control/safety. DNA microarray assays have been used widely for food safety and quality as well as searches for active components. DNA microarray-based gene expression profiling may be useful for such purposes due to its advantages in the evaluation of pathway-based intracellular signaling in response to food materials.
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Cremonesi P, Pozzi F, Raschetti M, Bignoli G, Capra E, Graber HU, Vezzoli F, Piccinini R, Bertasi B, Biffani S, Castiglioni B, Luini M. Genomic characteristics of Staphylococcus aureus strains associated with high within-herd prevalence of intramammary infections in dairy cows. J Dairy Sci 2015; 98:6828-38. [PMID: 26233457 DOI: 10.3168/jds.2014-9074] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 06/09/2015] [Indexed: 11/19/2022]
Abstract
Staphylococcus aureus is one of the most important causes of mastitis in dairy cattle. Based on previous research, Staph. aureus genotypes with different pathogenic and contagious properties can cause intramammary infection (IMI) and coexist in the same herd. Our study aimed to compare Staph. aureus strains from herds that differed in IMI prevalence using different molecular approaches such as ribosomal spacer (RS)-PCR, multilocus sequence typing (MLST), spa typing, ribotyping, pulsed-field gel electrophoresis (PFGE), and multiplex PCR. For this purpose, 31 dairy herds with Staph. aureus IMI were selected, and 16 of these were chosen for a comparison study: the 8 high-prevalence (HP) herds had Staph. aureus IMI prevalence >28% and the 8 low-prevalence (LP) herds had an IMI prevalence <4%. A total of 650 isolates of Staph. aureus from mammary quarters of all positive cows were genotyped with RS-PCR, a technique based on amplification of a portion of the intergenic spacer 16S-23S rRNA, and a subset of 54 strains was also analyzed by multiplex PCR, ribotyping, PFGE, MLST, and spa typing. The RS-PCR analysis revealed 12 different profiles. Staphylococcus aureus strains isolated from 5 out of 8 HP herds showed a profile identical to the genotype B (GTB), described in previous studies as being strongly associated with high within-herd prevalence of Staph. aureus mastitis and the presence of the genes coding for enterotoxins sea, sed, and sej, a long x-region of spa gene, and 3 lukE fragments. Moreover, all strains isolated in the HP herds possessed genes coding for staphylococcal enterotoxins. In LP herds, a limited number of strains of 6 genotypes, different from those isolated in HP herds, were identified and GTB was not found. Within these genotypes, 4 strains were positive for the mecA gene. Preliminary results and comparison with other genotyping methods confirmed that genotyping by RS-PCR is an accurate, rapid, and inexpensive tool for future field studies on Staph. aureus mastitis strains and generates clinically relevant results.
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Affiliation(s)
- P Cremonesi
- Istituto di Biologia e Biotecnologia Agraria, CNR, via Einstein, 26900 Lodi, Italy
| | - F Pozzi
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia, Sezione di Lodi, via Einstein, 26900 Lodi, Italy
| | - M Raschetti
- Istituto di Biologia e Biotecnologia Agraria, CNR, via Einstein, 26900 Lodi, Italy
| | - G Bignoli
- Istituto di Biologia e Biotecnologia Agraria, CNR, via Einstein, 26900 Lodi, Italy
| | - E Capra
- Istituto di Biologia e Biotecnologia Agraria, CNR, via Einstein, 26900 Lodi, Italy
| | - H U Graber
- Agroscope, Institute for Food Sciences (IFS), Schwarzenburgstrasse 161, CH-3003, Bern, Switzerland
| | - F Vezzoli
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia, Sezione di Lodi, via Einstein, 26900 Lodi, Italy
| | - R Piccinini
- Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, via Celoria, 20133 Milan, Italy
| | - B Bertasi
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia, Reparto Tecnologie Acidi Nucleici Applicate agli Alimenti, via Bianchi, 25124 Brescia, Italy
| | - S Biffani
- Istituto di Biologia e Biotecnologia Agraria, CNR, via Einstein, 26900 Lodi, Italy; Parco Tecnologico Padano, Via Einstein, 26900 Lodi, Italy
| | - B Castiglioni
- Istituto di Biologia e Biotecnologia Agraria, CNR, via Einstein, 26900 Lodi, Italy
| | - M Luini
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia, Sezione di Lodi, via Einstein, 26900 Lodi, Italy.
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Johler S, Giannini P, Jermini M, Hummerjohann J, Baumgartner A, Stephan R. Further evidence for staphylococcal food poisoning outbreaks caused by egc-encoded enterotoxins. Toxins (Basel) 2015; 7:997-1004. [PMID: 25802973 PMCID: PMC4379538 DOI: 10.3390/toxins7030997] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 03/18/2015] [Indexed: 11/30/2022] Open
Abstract
Staphylococcal food poisoning represents the most prevalent foodborne intoxication worldwide. It is caused by oral intake of enterotoxins preformed by Staphylococcus aureus in food. The relevance of newly described enterotoxins in outbreaks of staphylococcal food poisoning is controversially discussed. Although the staphylococcal enterotoxins SEG, SEI, SEM, SEN, and SEO elicit emesis in a monkey feeding assay, there has been no conclusive proof of their emetic activity in humans. In this study, we provide further evidence suggesting that one of these enterotoxins or a combination of SEG, SEI, SEM, SEN, and SEO cause staphylococcal food poisoning. We investigated two outbreaks registered with the Swiss Federal Office of Public Health, in which only Staphylococcus aureus strains harboring the egc cluster, including seg, sei, sem, sen, and seo linked to typical signs of staphylococcal food poisoning were isolated. The outbreaks were caused by consumption of raw goat cheese and semi-hard goat cheese, and were linked to strains assigned to CC45 (agr type I) and CC9 (agr type II), respectively. These outbreaks provide further evidence that newly-described staphylococcal enterotoxins are likely to cause staphylococcal food poisoning in humans.
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Affiliation(s)
- Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
| | - Petra Giannini
- Cantonal Laboratory, Via Mirasole 22, 6500 Bellinzona, Switzerland.
| | - Marco Jermini
- Cantonal Laboratory, Via Mirasole 22, 6500 Bellinzona, Switzerland.
| | - Jörg Hummerjohann
- Agroscope, Institute for Food Sciences, Schwarzenburgerstrasse 161, 3003 Bern, Switzerland.
| | - Andreas Baumgartner
- Federal Food Safety and Veterinary Office, Schwarzenburgerstrasse 155, 3003 Bern, Switzerland.
| | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
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Johler S, Weder D, Bridy C, Huguenin MC, Robert L, Hummerjohann J, Stephan R. Outbreak of staphylococcal food poisoning among children and staff at a Swiss boarding school due to soft cheese made from raw milk. J Dairy Sci 2015; 98:2944-8. [PMID: 25726108 DOI: 10.3168/jds.2014-9123] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 01/14/2015] [Indexed: 11/19/2022]
Abstract
On October 1, 2014, children and staff members at a Swiss boarding school consumed Tomme, a soft cheese produced from raw cow milk. Within the following 7h, all 14 persons who ingested the cheese fell ill, including 10 children and 4 staff members. Symptoms included abdominal pain and violent vomiting, followed by severe diarrhea and fever. We aim to present this food poisoning outbreak and characterize the causative agent. The duration of the incubation period was dependent of the age of the patient: 2.5h in children under 10 yr of age, 3.5h in older children and teenagers, and 7h in adults. The soft cheese exhibited low levels of staphylococcal enterotoxin (SE) A (>6ng of SEA/g of cheese) and high levels of staphylococcal enterotoxin D (>200ng of SED/g of cheese). Counts of 10(7) cfu of coagulase-positive staphylococci per gram of cheese were detected, with 3 different Staphylococcus aureus strains being present at levels >10(6) cfu/g. The 3 strains were characterized using spa typing and a DNA microarray. An enterotoxin-producing strain exhibiting sea and sed was identified as the source of the outbreak. The strain was assigned to spa type tbl 3555 and clonal complex 8, and it exhibited genetic criteria consistent with the characteristics of a genotype B strain. This genotype comprises bovine Staph. aureus strains exclusively associated with very high within-herd prevalence of mastitis and has been described as a major contaminant in Swiss raw milk cheese. It is therefore highly likely that the raw milk used for Tomme production was heavily contaminated with Staph. aureus and that levels further increased due to growth of the organism and physical concentration effects during the cheese-making process. Only a few staphylococcal food poisoning outbreaks involving raw milk products have been described. Still, in view of this outbreak and the possible occurrence of other foodborne pathogens in bovine milk, consumption of raw milk and soft cheese produced from raw milk constitutes a health risk, particularly when young children or other members of sensitive populations are involved.
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Affiliation(s)
- Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland.
| | - Delphine Weder
- Service de la Consommation et des Affaires Vétérinaires, Département du Développement Territorial et de l'Environnement République et Canton de Neuchâtel, 2001 Neuchâtel, Switzerland
| | - Claude Bridy
- Service de la Consommation et des Affaires Vétérinaires, Département du Développement Territorial et de l'Environnement République et Canton de Neuchâtel, 2001 Neuchâtel, Switzerland
| | - Marie-Claude Huguenin
- Service de la Consommation et des Affaires Vétérinaires, Département du Développement Territorial et de l'Environnement République et Canton de Neuchâtel, 2001 Neuchâtel, Switzerland
| | - Luce Robert
- Service de la Consommation et des Affaires Vétérinaires, Département du Développement Territorial et de l'Environnement République et Canton de Neuchâtel, 2001 Neuchâtel, Switzerland
| | | | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland
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30
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Liang M, Zhang T, Liu X, Fan Y, Xia S, Xiang Y, Liu Z, Jinnian L. Development of an indirect competitive enzyme-linked immunosorbent assay based on the multiepitope peptide for the synchronous detection of staphylococcal enterotoxin A and G proteins in milk. J Food Prot 2015; 78:362-9. [PMID: 25710152 DOI: 10.4315/0362-028x.jfp-14-323] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Staphylococcal food poisoning (SFP), one of the most common foodborne diseases, results from ingestion of staphylococcal enterotoxins (SEs) in foods. In our previous studies, we found that SEA and SEG were two predominant SE proteins produced by milkacquired S. aureus isolates. Here, a tandemly arranged multiepitope peptide (named SEAGepis) was designed with six linear B-cell epitopes derived from SEA or SEG and was heterologously expressed. The SEAGepis-specific antibody was prepared by immunizing rabbit with rSEAGepis. Then, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on rSEAGepis and the corresponding antibody was developed to simultaneously detect SEA and SEG. Under the optimized conditions, the ic-ELISA standard curve for rSEAGepis was constructed in the concentration range of 0.5 to 512 ng/ml, and the average coefficients of variation of intra- and interassay were 4.28 and 5.61% during six standard concentrations. The average half-maximal inhibitory concentration was 5.07 ng/ml, and the limit of detection at a signal-to-noise ratio of 3 was 0.52 ng/ml. The anti-rSEAGepis antibody displayed over 90% cross-reactivity with SEA and SEG but less than 0.5% cross-reactivity with other enterotoxins. Artificially contaminated milk with different concentrations of rSEAGepis, SEA, and SEG was detected by the established ic-ELISA; the recoveries of rSEAGepis, SEA, and SEG were 91.1 to 157.5%, 90.3 to 134.5%, and 89.1 to 117.5%, respectively, with a coefficient of variation below 12%. These results demonstrated that the newly established ic-ELISA possessed high sensitivity, specificity, stability, and accuracy and could potentially be a useful analytical method for synchronous detection of SEA and SEG in milk.
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Affiliation(s)
- Mingyan Liang
- College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang Avenue, Hefei 230036, Anhui, People's Republic of China
| | - Tingting Zhang
- College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang Avenue, Hefei 230036, Anhui, People's Republic of China
| | - Xuelan Liu
- College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang Avenue, Hefei 230036, Anhui, People's Republic of China
| | - Yanan Fan
- College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang Avenue, Hefei 230036, Anhui, People's Republic of China
| | - Shenglin Xia
- Center of Animal Epidemic Disease Prevention and Control, 460 Liming Avenue, Wuhu 241000, Anhui, People's Republic of China
| | - Yiqing Xiang
- College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang Avenue, Hefei 230036, Anhui, People's Republic of China
| | - Ziqi Liu
- College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang Avenue, Hefei 230036, Anhui, People's Republic of China
| | - Li Jinnian
- College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang Avenue, Hefei 230036, Anhui, People's Republic of China.
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31
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Samelis J, Lianou A, Pappa EC, Bogovič-Matijašić B, Parapouli M, Kakouri A, Rogelj I. Behavior of Staphylococcus aureus in culture broth, in raw and thermized milk, and during processing and storage of traditional Greek Graviera cheese in the presence or absence of Lactococcus lactis subsp. cremoris M104, a wild, novel nisin A-producing raw milk isolate. J Food Prot 2014; 77:1703-14. [PMID: 25285487 DOI: 10.4315/0362-028x.jfp-14-105] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study was conducted to evaluate the behavior of Staphylococcus aureus during processing, ripening, and storage of traditional Greek Graviera cheese in accordance with European Union Regulation 1441/2007 for coagulase-positive staphylococci in thermized milk cheeses. Lactococcus lactis subsp. cremoris M104, a wild, novel nisin A-producing (NisA+) strain, also was evaluated as an antistaphylococcal adjunct. A three-strain cocktail of enterotoxigenic (Ent+) S. aureus increased by approximately 2 log CFU/ml when co-inoculated (at approximately 3 log CFU/ml) in thermized Graviera cheese milk (TGCM; 63°C for 30 s) with commercial starter culture (CSC) and/or strain M104 at approximately 6 log CFU/ml and then incubated at 37°C for 3 h. However, after 6 h at 37°C, significant retarding effects on S. aureus growth were noted in the order TGCM + M104 > TGCM + CSC = TGCM + CSC + M104 > TGCM. Additional incubation of TGCM cultures at 18°C for 66 h resulted in a 1.2-log reduction (P < 0.05) of S. aureus populations in TGCM + M104. The Ent + S. aureus cocktail did not grow but survived during ripening and storage when inoculated (at approximately 3 log CFU/g) postcooking into Graviera mini cheeses prepared from TGCM + CSC or TGCM + CSC + M104, ripened at 18°C and 90% relative humidity for 20 days, and stored at 4°C in vacuum packages for 2 months. A rapid 10-fold decrease (P < 0.05) in S. aureus populations occurred within the first 24 h of cheese fermentation. Reductions of S. aureus were greater by approximately 0.4 log CFU/g in CSC + M104 than in CSC only cheeses, concomitantly with the presence of NisA + M104 colonies and nisin-encoding genes in the CSC plus M104 cheeses and their corresponding microbial consortia only. A high level of selective survival of a naturally nisin-resistant EntC z S. aureus strain from the cocktail was noted in CSC + M104 cheeses and in coculture with the NisA + M104 strain in M-17 broth. In conclusion, although S. aureus growth inhibition is assured during Graviera cheese ripening, early growth of the pathogen during milk curdling and curd cooking operations may occur. Nisin-resistant S. aureus strains that may contaminate Graviera cheese milks postthermally may be difficult to control even by the application of the NisA + L. lactis subsp. cremoris strain M104 as a bioprotective adjunct culture.
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Affiliation(s)
- John Samelis
- Dairy Research Institute, Directorate General of Agricultural Research, Hellenic Agricultural Organization DEMETER, Katsikas, 45221 Ioannina, Greece.
| | - Alexandra Lianou
- Dairy Research Institute, Directorate General of Agricultural Research, Hellenic Agricultural Organization DEMETER, Katsikas, 45221 Ioannina, Greece; Laboratory of Food Microbiology and Biotechnology, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - Eleni C Pappa
- Dairy Research Institute, Directorate General of Agricultural Research, Hellenic Agricultural Organization DEMETER, Katsikas, 45221 Ioannina, Greece
| | | | - Maria Parapouli
- Dairy Research Institute, Directorate General of Agricultural Research, Hellenic Agricultural Organization DEMETER, Katsikas, 45221 Ioannina, Greece; Laboratory of Biochemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece
| | - Athanasia Kakouri
- Dairy Research Institute, Directorate General of Agricultural Research, Hellenic Agricultural Organization DEMETER, Katsikas, 45221 Ioannina, Greece
| | - Irena Rogelj
- Biotechnical Faculty, University of Ljubljana, SI-1230 DomŽale, Slovenia
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32
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Kaźmierczak Z, Górski A, Dąbrowska K. Facing antibiotic resistance: Staphylococcus aureus phages as a medical tool. Viruses 2014; 6:2551-70. [PMID: 24988520 PMCID: PMC4113783 DOI: 10.3390/v6072551] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus is a common and often virulent pathogen in humans. This bacterium is widespread, being present on the skin and in the nose of healthy people. Staphylococcus aureus can cause infections with severe outcomes ranging from pustules to sepsis and death. The introduction of antibiotics led to a general belief that the problem of bacterial infections would be solved. Nonetheless, pathogens including staphylococci have evolved mechanisms of drug resistance. Among current attempts to address this problem, phage therapy offers a promising alternative to combat staphylococcal infections. Here, we present an overview of current knowledge on staphylococcal infections and bacteriophages able to kill Staphylococcus, including experimental studies and available data on their clinical use.
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Affiliation(s)
- Zuzanna Kaźmierczak
- Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. R. Weigla 12, Wroclaw 53-114, Poland.
| | - Andrzej Górski
- Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. R. Weigla 12, Wroclaw 53-114, Poland.
| | - Krystyna Dąbrowska
- Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. R. Weigla 12, Wroclaw 53-114, Poland.
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33
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Baumgartner A, Niederhauser I, Johler S. Virulence and resistance gene profiles of staphylococcus aureus strains isolated from ready-to-eat foods. J Food Prot 2014; 77:1232-6. [PMID: 24988036 DOI: 10.4315/0362-028x.jfp-14-027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Staphylococcal food poisoning represents the most prevalent foodborne intoxication worldwide. Oral intake of staphylococcal enterotoxins from food can result in emesis and diarrhea and can be fatal in children and the elderly. Few data have been available on the characteristics and sources of Staphylococcus aureus strains isolated from ready-to-eat (RTE) foods. In this study, we used a DNA microarray to determine virulence and antimicrobial resistance gene profiles of S. aureus from RTE foods. A total of 267 S. aureus strains isolated from 244 RTE foods were investigated. The isolates originated from precooked foods (41% of isolates), meat and fish products (17%), cheese (13%), delicatessen salads (8%), sandwiches and canapés (8%), confectionery and bakery products (6%), and various other RTE foods (7%). Eleven samples (5%), of which 9 were raw milk cheeses, contained > 10(5) CFU/g, which is considered a health risk. Four S. aureus strains were associated with intoxications; three cases were linked to consumption of cheese and one case was linked to consumption of potato salad. DNA microarray results revealed that one-third of the tested strains had at least one major enterotoxin gene (sea through see). We also detected the toxic shock syndrome gene (18% of isolates) and various genes conferring antimicrobial resistance, including genes involved in resistance to beta-lactams (blaZ, 72% of isolates), methicillin (mecA, 1% of isolates), and vancomycin (vanB, 1% of isolates). S. aureus strains were most frequently assigned to clonal complex (CC) 30 (17% of isolates), CC8 (12%), CC15 (11%), and CC45 (10%), which are commonly detected in humans colonized or infected with S. aureus. Although a large proportion of the tested food items contained milk, we did not detect CC705, the most prevalent clonal complex among S. aureus isolates from bovine mastitis milk. Our results suggest that S. aureus isolates from RTE foods do not commonly originate from animals but more likely come from food handlers who contaminate foods.
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Affiliation(s)
- Andreas Baumgartner
- Federal Food Safety and Veterinary Office, Schwarzenburgstrasse 155, 3003 Bern, Switzerland
| | - Isabel Niederhauser
- Federal Food Safety and Veterinary Office, Schwarzenburgstrasse 155, 3003 Bern, Switzerland
| | - Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 272, CH-8057 Zurich, Switzerland.
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Fusco V, Quero GM. Culture-Dependent and Culture-Independent Nucleic-Acid-Based Methods Used in the Microbial Safety Assessment of Milk and Dairy Products. Compr Rev Food Sci Food Saf 2014; 13:493-537. [DOI: 10.1111/1541-4337.12074] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/08/2014] [Indexed: 12/12/2022]
Affiliation(s)
- Vincenzina Fusco
- Nal. Research Council of Italy; Inst. of Sciences of Food Production (CNR-ISPA); Bari Italy
| | - Grazia Marina Quero
- Nal. Research Council of Italy; Inst. of Sciences of Food Production (CNR-ISPA); Bari Italy
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Robles BF, Nóbrega DB, Guimarães FF, Wanderley GG, Langoni H. Beta-lactamase detection in Staphylococcus aureus and coagulase-negative Staphylococcus isolated from bovine mastitis. PESQUISA VETERINARIA BRASILEIRA 2014. [DOI: 10.1590/s0100-736x2014000400004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The objectives of the study were to evaluate the presence/production of beta-lactamases by both phenotypic and genotypic methods, verify whether results are dependent of bacteria type (Staphylococcus aureus versus coagulase-negative Staphylococcus - CNS) and verify the agreement between tests. A total of 200 bacteria samples from 21 different herds were enrolled, being 100 CNS and 100 S. aureus. Beta-lactamase presence/detection was performed by different tests (PCR, clover leaf test - CLT, Nitrocefin disk, and in vitro resistance to penicillin). Results of all tests were not dependent of bacteria type (CNS or S. aureus). Several S. aureus beta-lactamase producing isolates were from the same herd. Phenotypic tests excluding in vitro resistance to penicillin showed a strong association measured by the kappa coefficient for both bacteria species. Nitrocefin and CLT are more reliable tests for detecting beta-lactamase production in staphylococci.
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Hummerjohann J, Naskova J, Baumgartner A, Graber HU. Enterotoxin-producing Staphylococcus aureus genotype B as a major contaminant in Swiss raw milk cheese. J Dairy Sci 2014; 97:1305-12. [PMID: 24440268 DOI: 10.3168/jds.2013-7643] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 11/24/2013] [Indexed: 11/19/2022]
Abstract
The objective of this study was to characterize Staphylococcus aureus isolates from Swiss raw milk cheeses that had been found to be contaminated with coagulase-positive staphylococci and to estimate the frequency of the various genotypes, in particular the mastitis-associated Staph. aureus genotype B (GTB). The isolates were also tested for staphylococcal enterotoxin (SE) genes and other virulence factors. From 623 coagulase-positive staphylococci isolated from 78 contaminated raw milk cheeses, 609 were found to be Staphylococcus aureus. Genotyping of all Staph. aureus isolates was performed by PCR amplification of the 16S-23S rRNA intergenic spacer region, as this method was used previously to differentiate between mastitis subtypes associated with their clinical outcome. In total, 20 different genotypes were obtained and the 5 most frequently occurring genotypes were distributed in 6.4% or more of the samples. The enterotoxin-producing Staph. aureus GTB, known for its high contagiousness and increased pathogenicity in Swiss mastitis herds, was found to be the most abundant subtype at the sample level (71.8%) as well as among the isolates (62.0%). A subset of 107 isolates of the different genotypes were analyzed for the presence of SE genes and revealed 9 different SE gene patterns, with sed being most frequently detected and 26% being PCR-negative for SE genes. Almost all isolates of the major contaminant GTB contained the SE gene pattern sed, sej, ser, with half of them additionally carrying sea. Production of SE in vitro was consistent with the SE genes detected in most of the cases; however, some isolated GTB did not produce SEA. Staphylococcus aureus Protein A (spa) typing revealed 30 different subtypes and most GTB isolates belonged to the bovine spa type t2953; GTB/t2953 was linked among other subtypes to SE production in cheese and staphylococcal intoxication cases. Furthermore, 1 of the 623 isolates was a methicillin-resistant Staph. aureus, which was an seh-carrying Staph. aureus spa type tbl 0635 (non-GTB). We conclude that control and reduction of enterotoxigenic Staph. aureus GTB in dairy herds in Switzerland will not only prevent economic losses at the farm level but also improve the safety of raw milk cheeses; distribution of methicillin-resistant Staph. aureus via raw milk cheese is of less concern.
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Affiliation(s)
- J Hummerjohann
- Agroscope Liebefeld-Posieux Research Station ALP-Haras, Schwarzenburgstrasse 161, 3003 Berne, Switzerland.
| | - J Naskova
- Agroscope Liebefeld-Posieux Research Station ALP-Haras, Schwarzenburgstrasse 161, 3003 Berne, Switzerland
| | - A Baumgartner
- Swiss Federal Office of Public Health, Schwarzenburgstrasse 165, 3003 Berne, Switzerland
| | - H U Graber
- Agroscope Liebefeld-Posieux Research Station ALP-Haras, Schwarzenburgstrasse 161, 3003 Berne, Switzerland
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Silva N, Guimarães F, Manzi M, Budri P, Gómez-Sanz E, Benito D, Langoni H, Rall V, Torres C. Molecular characterization and clonal diversity of methicillin-susceptible Staphylococcus aureus in milk of cows with mastitis in Brazil. J Dairy Sci 2013; 96:6856-6862. [DOI: 10.3168/jds.2013-6719] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 07/22/2013] [Indexed: 12/15/2022]
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