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Forouzani‐Moghaddam MJ, Habibi S, Hosseini‐Safa A, Khanaliha K, Mokarinejad R, Akhoundzadeh F, Oshaghi M. Rapid detection of major enterotoxin genes and antibiotic resistance of Staphylococcus aureus isolated from raw milk in the Yazd province, Iran. Vet Med Sci 2024; 10:e1407. [PMID: 38519836 PMCID: PMC10959825 DOI: 10.1002/vms3.1407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 01/22/2024] [Accepted: 02/19/2024] [Indexed: 03/25/2024] Open
Abstract
INTRODUCTION Raw milk is a nutrient-rich food, but it may harbour harmful bacteria, such as enterotoxigenic Staphylococcus aureus (S. aureus), which can cause staphylococcal food poisoning. Antibiotic resistance of S. aureus in raw milk can increase the risk of such infections, particularly among susceptible individuals. OBJECTIVE This study aimed to investigate the prevalence of enterotoxin genes a, d, g, i and j and the antibiotic resistance of S. aureus isolated from raw milk samples. METHODS During a 6-month sampling period, 60 raw milk specimens were obtained from diverse locations in Yazd province, Iran. Antibiogram profiling was conducted via the disc diffusion method. In addition, staphylococcal enterotoxin (SE) genes a, d, g, i, and j were detected through real-time PCR analysis. RESULTS Bacteriological assays confirmed the presence of S. aureus in 11 samples (18.3%). All isolates demonstrated 100% resistance to penicillin G but exhibited sensitivity to vancomycin, while resistance to other antibiotics ranged from 36.4% to 45.5%. The prevalence of enterotoxin genes in these strains showed variable distribution, with sea being the predominant SE (45.5%), followed by sed (36.4%), seg (18.2), sej and sei (9.1% each). CONCLUSIONS This study discovered the presence of multiple enterotoxins in S. aureus strains obtained from raw milk samples. These strains also demonstrated resistance to a variety of antibiotics. Since enterotoxigenic S. aureus is known to cause human food poisoning, monitoring food hygiene practices, especially during raw milk production, is critical.
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Affiliation(s)
| | - Sina Habibi
- Department of Medical Laboratory SciencesFaculty of Allied MedicineIran University of Medical SciencesTehranIran
- Department of Hematology and Blood Banking, Faculty of Allied MedicineIran University of Medical SciencesTehranIran
| | - Ahmad Hosseini‐Safa
- Department of Medical Laboratory SciencesFaculty of Allied MedicineIran University of Medical SciencesTehranIran
| | - Khadijeh Khanaliha
- Research Center of Pediatric Infectious DiseasesInstitute of Immunology and Infectious DiseasesIran University of Medical SciencesTehranIran
| | - Roya Mokarinejad
- Department of Medical Laboratory SciencesFaculty of Allied MedicineIran University of Medical SciencesTehranIran
| | - Fatemeh Akhoundzadeh
- Department of Medical Laboratory SciencesFaculty of Allied MedicineIran University of Medical SciencesTehranIran
| | - Mojgan Oshaghi
- Department of Medical Laboratory SciencesFaculty of Allied MedicineIran University of Medical SciencesTehranIran
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Deddefo A, Mamo G, Asfaw M, Edao A, Hiko A, Fufa D, Jafer M, Sombo M, Amenu K. Occurrence, antimicrobial susceptibility, and resistance genes of Staphylococcus aureus in milk and milk products in the Arsi highlands of Ethiopia. BMC Microbiol 2024; 24:127. [PMID: 38627609 PMCID: PMC11020821 DOI: 10.1186/s12866-024-03288-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 04/02/2024] [Indexed: 04/19/2024] Open
Abstract
BACKGROUND In Ethiopia, milk production and handling practices often lack proper hygiene measures, leading to the potential contamination of milk and milk products with Staphylococcus aureus (S. aureus), including methicillin-resistant strains, posing significant public health concerns. This study aimed to investigate the occurrence, antimicrobial susceptibility profiles and presence of resistance genes in S. aureus strains isolated from milk and milk products. METHODS A cross-sectional study was conducted in the Arsi highlands, Oromia, Ethiopia from March 2022 to February 2023. A total of 503 milk and milk product samples were collected, comprising 259 raw milk, 219 cottage cheese, and 25 traditional yogurt samples. S. aureus isolation and coagulase-positive staphylococci enumeration were performed using Baird-Parker agar supplemented with tellurite and egg yolk. S. aureus was further characterized based on colony morphology, Gram stain, mannitol fermentation, catalase test, and coagulase test. Phenotypic antimicrobial resistance was assessed using the Kirby-Bauer disc diffusion method, while the polymerase chain reaction (PCR) was employed for confirming the presence of S. aureus and detecting antimicrobial resistance genes. RESULTS S. aureus was detected in 24.9% of the milk and milk products, with the highest occurrence in raw milk (40.9%), followed by yogurt (20%), and cottage cheese (6.4%). The geometric mean for coagulase-positive staphylococci counts in raw milk, yogurt, and cottage cheese was 4.6, 3.8, and 3.2 log10 CFU/mL, respectively. Antimicrobial resistance analysis revealed high levels of resistance to ampicillin (89.7%) and penicillin G (87.2%), with 71.8% of the isolates demonstrating multidrug resistance. Of the 16 S. aureus isolates analyzed using PCR, all were found to carry the nuc gene, with the mecA and blaZ genes detected in 50% of these isolates each. CONCLUSION This study revealed the widespread distribution of S. aureus in milk and milk products in the Arsi highlands of Ethiopia. The isolates displayed high resistance to ampicillin and penicillin, with a concerning level of multidrug resistance. The detection of the mecA and blaZ genes in selected isolates is of particular concern, highlighting a potential public health hazard and posing a challenge to effective antimicrobial treatment. These findings highlight the urgent need to enhance hygiene standards in milk and milk product handling and promote the rational use of antimicrobial drugs. Provision of adequate training for all individuals involved in the dairy sector can help minimize contamination. These measures are crucial in addressing the threats posed by S. aureus, including methicillin-resistant strains, and ensuring the safety of milk and its products for consumers.
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Affiliation(s)
- Abiot Deddefo
- College of Agriculture and Environmental Sciences, Arsi University, P.O. Box 193, Asella, Ethiopia.
- College of Veterinary Medicine and Agriculture, Addis Ababa University, P.O. Box 34, Bishoftu, Ethiopia.
| | - Gezahegne Mamo
- College of Veterinary Medicine and Agriculture, Addis Ababa University, P.O. Box 34, Bishoftu, Ethiopia
| | - Minda Asfaw
- College of Agriculture and Environmental Sciences, Arsi University, P.O. Box 193, Asella, Ethiopia
| | - Adem Edao
- College of Veterinary Medicine, Haramaya University, P.O. Box 138, Haramaya, Ethiopia
| | - Adem Hiko
- College of Veterinary Medicine, Haramaya University, P.O. Box 138, Haramaya, Ethiopia
| | - Dereje Fufa
- Asella Regional Veterinary Laboratory, P.O. Box 212, Asella, Ethiopia
| | - Mohammed Jafer
- College of Veterinary Medicine, Haramaya University, P.O. Box 138, Haramaya, Ethiopia
| | - Melaku Sombo
- National Animal Health Institute, P.O. Box 04, Sebeta, Ethiopia
| | - Kebede Amenu
- College of Veterinary Medicine and Agriculture, Addis Ababa University, P.O. Box 34, Bishoftu, Ethiopia
- Animal and Human Health Programme, International Livestock Research Institute (ILRI), P.O. Box 5689, Addis Ababa, Ethiopia
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Jurado A, Fernández L, Rodríguez A, García P. Prevalence of virulence- and antibiotic resistance-associated genotypes and phenotypes in Staphylococcus aureus strains from the food sector compared to clinical and cow mastitis isolates. Front Cell Infect Microbiol 2024; 14:1327131. [PMID: 38348375 PMCID: PMC10859521 DOI: 10.3389/fcimb.2024.1327131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 01/12/2024] [Indexed: 02/15/2024] Open
Abstract
Background Infections by the pathogen Staphylococcus aureus currently represent one of the most serious threats to human health worldwide, especially due to the production of enterotoxins and the ability to form biofilms. These structures and the acquisition of antibiotic resistance limit the action of antibiotics and disinfectants used to combat this microorganism in the industry and the clinic. Methods This work reports a comparative phenotypic and genotypic study of 18 S. aureus strains from different origins: clinical samples, milk from mastitic cows and food industry surfaces, most of which were isolated in Northern Spain. Results Genetically, the strains were very diverse but, in most cases, a closer proximity was observed for those from the same source. Notably, the average number of virulence genes was not significantly different in strains from the food sector. Of the 18 strains, 10 coded for at least one enterotoxin, and four of them carried 6 or 7 enterotoxin genes. The latter were all veterinary or clinical isolates. Most strains carried prophages, plasmids and/or pathogenicity islands. Regarding antibiotic resistance, although phenotypically all strains showed resistance to at least one antibiotic, resistance genes were only identified in 44.5% of strains, being mastitis isolates those with the lowest prevalence. Virulence-related phenotypic properties such as haemolytic activity, staphyloxanthin production, biofilm-forming capacity and spreading ability were widely distributed amongst the isolates. Conclusions Our results indicate that production of virulence factors, antibiotic resistance and biofilm formation can be found in S. aureus isolates from diverse environments, including the food industry, although some of these traits are more prevalent in strains isolated from infections in cows or humans. This emphasizes on the importance of monitoring the spread of these determinants not only in samples from the clinical environment, but also along the food chain, a strategy that falls under the prism of a one-health approach.
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Affiliation(s)
- Andrea Jurado
- Department of Technology and Biotechnology, Instituto de Productos Lácteos de Asturias (IPLA-CSIC), Asturias, Spain
- DairySafe Group. Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain
| | - Lucía Fernández
- Department of Technology and Biotechnology, Instituto de Productos Lácteos de Asturias (IPLA-CSIC), Asturias, Spain
- DairySafe Group. Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain
| | - Ana Rodríguez
- Department of Technology and Biotechnology, Instituto de Productos Lácteos de Asturias (IPLA-CSIC), Asturias, Spain
- DairySafe Group. Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain
| | - Pilar García
- Department of Technology and Biotechnology, Instituto de Productos Lácteos de Asturias (IPLA-CSIC), Asturias, Spain
- DairySafe Group. Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain
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Zhang Z, Wang J, Wang H, Zhang L, Shang W, Li Z, Song L, Li T, Cheng M, Zhang C, Zhao Q, Shen S, Cui M. Molecular Surveillance of MRSA in Raw Milk Provides Insight into MRSA Cross Species Evolution. Microbiol Spectr 2023; 11:e0031123. [PMID: 37260406 PMCID: PMC10433870 DOI: 10.1128/spectrum.00311-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 05/16/2023] [Indexed: 06/02/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) in foods has been associated with severe infections in humans and animals worldwide. In the present study, the molecular characteristics of livestock-associated MRSA (LA-MRSA) and human-associated MRSA (hMRSA) isolates obtained in China, as well as MRSA isolates obtained from raw milk in 2018, were investigated. In total, 343 (20.38%; 343/1,683) S. aureus isolates were obtained from 1,683 raw milk samples from 100 dairy farms in 11 provinces across China. Among these, 49 (2.91%; 49/1,683) were mecA-positive MRSA. All LA-MRSA isolates were resistant to penicillin and highly resistant to erythromycin, sulfisoxazole, and clindamycin. Bioinformatic analysis the 49 genomes of LA-MRSA and 71 previously published hMRSA genomes isolated from Chinese individuals in 2018 indicated that blaZ, erm, ant(6)-Ia, aph(3')-III, tet(K), cat, and aph(2″)-Ia were more prevalent in MRSA from raw milk (P < 0.05) compared to hMRSA. Additionally, hMRSA isolates were more significantly associated with ST5 (P < 0.01) compared to LA-MRSA; in contrast, ST338 was more prevalent among LA-MRSA isolates (P < 0.01). Likewise, the SCCmec type II was only detected in hMRSA isolates, whereas SCCmec type V and IV were more prevalent among LA-MRSA (P < 0.01). Furthermore, core-genome phylogenetic analysis showed the endemic characteristics of LA-MRSA in local provinces, as well as the close evolutionary relationships between MRSA from cattle and humans. Finally, homology analysis of mecA and blaZ genetic contexts revealed a high possibility of horizontal transmission of MRSA resistance genes among raw milk-associated and hMRSA strains, which increases the risk for public health. IMPORTANCE Methicillin-resistant Staphylococcus aureus (MRSA) is considered a public health concern as it is resistant to multiple antibiotics, thus being in zoonotic transmission of antibiotic resistance genes. MRSA causes serious public health issues and leads to hard-to-treat infections in humans and animals; therefore, it was meaningful to determine the prevalence of MRSA in raw milk samples and investigate phenotype and genotype of antimicrobial resistance and molecular characteristics in livestock-associated MRSA (LA-MRSA) and human-associated MRSA (hMRSA) in China, which could provide a theoretical basis for preventing and controlling the spread of MRSA between livestock and humans.
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Affiliation(s)
- Zhenbiao Zhang
- Shanxi Key Laboratory for Modernization of TCVM, College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong, Shanxi, People’s Republic of China
| | - Jianzhong Wang
- Shanxi Key Laboratory for Modernization of TCVM, College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong, Shanxi, People’s Republic of China
| | - Hejia Wang
- China Institute of Veterinary Drug Control, Beijing, People’s Republic of China
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, People’s Republic of China
| | - Liu Zhang
- College of Agricultural Standardization, Shanxi Agricultural University, Jinzhong, Shanxi, People’s Republic of China
| | - Wei Shang
- No.988 Hospital of Joint Logistic Support Force, Zhengzhou, Henan, People’s Republic of China
| | - Zekun Li
- China Institute of Veterinary Drug Control, Beijing, People’s Republic of China
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, People’s Republic of China
| | - Li Song
- China Institute of Veterinary Drug Control, Beijing, People’s Republic of China
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, People’s Republic of China
| | - Ting Li
- China Institute of Veterinary Drug Control, Beijing, People’s Republic of China
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, People’s Republic of China
| | - Min Cheng
- China Institute of Veterinary Drug Control, Beijing, People’s Republic of China
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, People’s Republic of China
| | - Chunping Zhang
- China Institute of Veterinary Drug Control, Beijing, People’s Republic of China
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, People’s Republic of China
| | - Qi Zhao
- China Institute of Veterinary Drug Control, Beijing, People’s Republic of China
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, People’s Republic of China
| | - Shan Shen
- Shandong Provincial Hospital (Group) Ludong Hospital, Yantai, Shandong, People’s Republic of China
| | - Mingquan Cui
- China Institute of Veterinary Drug Control, Beijing, People’s Republic of China
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, People’s Republic of China
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Dendani Chadi Z, Arcangioli MA. Pulsed-Field Gel Electrophoresis Analysis of Bovine Associated Staphylococcus aureus: A Review. Pathogens 2023; 12:966. [PMID: 37513813 PMCID: PMC10385338 DOI: 10.3390/pathogens12070966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/10/2023] [Accepted: 07/14/2023] [Indexed: 07/30/2023] Open
Abstract
For decades now, DNA fingerprinting by means of pulsed-field gel electrophoresis (PFGE) continues to be the most widely used to separate large DNA molecules and distinguish between different strains in alternating pulses. This is done by isolating intact chromosomal DNA and using restriction enzymes with specific restriction sites to generate less than 30 restriction fragments from 50 Kb to 10 Mbp. These results make clone-specific band profiles easy to compare. Specialized equipment is required for the optimization of DNA separation and resolution, among which a contour-clamped homogeneous electric field (CHEF) apparatus is the most commonly used. As a result, the PFGE analysis of a bacterial genome provides useful information in terms of epidemiological investigations of different bacterial pathogens. For Staphylococcus aureus subtyping, despite its limitations and the emergence of alternative methods, PFGE analysis has proven to be an adequate choice and the gold standard for determining genetic relatedness, especially in outbreak detection and short-term surveillance in the veterinary field.
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Affiliation(s)
- Zoubida Dendani Chadi
- Laboratory of Biodiversity and Pollution of Ecosystems, Department of Veterinary Medicine, Faculty of Natural Science and Life, University of Chadli Bendjedid, El Tarf 36000, Algeria
| | - Marie-Anne Arcangioli
- VetAgro Sup, Université de Lyon, UMR Mycoplasmoses Animales, 69280 Marcy l'Etoile, France
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Lim KL, Khor WC, Ong KH, Timothy L, Aung KT. Occurrence and Patterns of Enterotoxin Genes, spa Types and Antimicrobial Resistance Patterns in Staphylococcus aureus in Food and Food Contact Surfaces in Singapore. Microorganisms 2023; 11:1785. [PMID: 37512957 PMCID: PMC10386305 DOI: 10.3390/microorganisms11071785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/12/2023] [Accepted: 07/08/2023] [Indexed: 07/30/2023] Open
Abstract
Staphylococcus aureus contamination of food and food contact surfaces is a public health concern given its virulent and antimicrobial-resistant properties worldwide. In this study, a total of 181 MSSA isolates were analyzed for SE genes, antimicrobial resistance patterns, and spa types. Overall, 24.9% of isolates were positive for SE gene detection, with sea being the most prevalent classical SE (18.8%). The most predominant sample sources for SE gene contamination were hand swabs for sea (6/48), meat dishes for seb (3/14) and seafood dishes for sec (2/24). Antimicrobial resistance was also observed at relatively high frequencies for the clinically important antibiotics penicillin G and ampicillin (both 54.7%), followed by tetracycline (14.9%) and azithromycin (8.8%). In addition, characterization of spa types revealed spa type t5078 to be the most predominant (40.3%), with significant associations between spa types t127 and t5521 and the sea gene. This study offers insights into the enterotoxin gene and antimicrobial resistance profiles of S. aureus in cooked or ready-to-eat food to inform future surveillance and epidemiological studies.
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Affiliation(s)
- Ker Li Lim
- National Centre for Food Science, Singapore Food Agency, 7 International Business Park, Techquest, Singapore 609919, Singapore
| | - Wei Ching Khor
- National Centre for Food Science, Singapore Food Agency, 7 International Business Park, Techquest, Singapore 609919, Singapore
| | - Kar Hui Ong
- National Centre for Food Science, Singapore Food Agency, 7 International Business Park, Techquest, Singapore 609919, Singapore
| | - Lois Timothy
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Dr, Singapore 637551, Singapore
| | - Kyaw Thu Aung
- National Centre for Food Science, Singapore Food Agency, 7 International Business Park, Techquest, Singapore 609919, Singapore
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Dr, Singapore 637551, Singapore
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Brandelli A, Lopes NA, Pinilla CMB. Nanostructured Antimicrobials for Quality and Safety Improvement in Dairy Products. Foods 2023; 12:2549. [PMID: 37444286 DOI: 10.3390/foods12132549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 06/26/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023] Open
Abstract
In the food sector, one of the most important economic activities is the dairy industry, which has been facing many challenges in order to meet the increasing demand by consumers for natural and minimally processed products with high quality. In this sense, the application of innovative and emerging technologies can be an interesting alternative, for example, the use of nanotechnology in packaging and as delivery systems. This technology has the potential to improve the quality and safety of dairy products, representing an interesting approach for delivering food preservatives and improving the mechanical, barrier and functional properties of packaging. Several applications and promising results of nanostructures for dairy product preservation can be found throughout this review, including the use of metallic and polymeric nanoparticles, lipid-based nanostructures, nanofibers, nanofilms and nanocoatings. In addition, some relevant examples of the direct application of nanostructured natural antimicrobials in milk and cheese are presented and discussed, as well as the use of milk agar as a model for a preliminary test. Despite their high cost and the difficulties for scale-up, interesting results of these technologies in dairy foods and packaging materials have promoted a growing interest of the dairy industry.
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Affiliation(s)
- Adriano Brandelli
- Laboratory of Nanobiotechnology and Applied Microbiology, Department of Food Science, Federal University of Rio Grande do Sul, Porto Alegre 91501-970, Brazil
| | - Nathalie Almeida Lopes
- Laboratory of Nanobiotechnology and Applied Microbiology, Department of Food Science, Federal University of Rio Grande do Sul, Porto Alegre 91501-970, Brazil
| | - Cristian Mauricio Barreto Pinilla
- Laboratory of Nanobiotechnology and Applied Microbiology, Department of Food Science, Federal University of Rio Grande do Sul, Porto Alegre 91501-970, Brazil
- Dairy Technology Center, Institute of Food Technology, Campinas 13083-015, Brazil
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Deddefo A, Mamo G, Asfaw M, Amenu K. Factors affecting the microbiological quality and contamination of farm bulk milk by Staphylococcus aureus in dairy farms in Asella, Ethiopia. BMC Microbiol 2023; 23:65. [PMID: 36882721 PMCID: PMC9990340 DOI: 10.1186/s12866-022-02746-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 12/21/2022] [Indexed: 03/09/2023] Open
Abstract
BACKGROUND The determination of the microbiological quality and safety of raw milk and the associated influencing factors at the farm level is very critical given that the quality or safety of subsequent products that are further produced depends on this. Therefore, this study aimed to determine the microbiological quality and safety of bulk milk and identify associated risk factors, and assess the presence/absence of S. aureus in bulk milk with potential contaminating sources in dairy farms in Asella, Ethiopia. RESULTS The geometric means of bacterial counts in farm bulk milk were 5.25 log cfu/ml, 3.1 log cfu/ml and 2.97 log cfu/ml for total bacterial count (TBC), coliform count (CC) and coagulase-positive staphylococci count (CPS), respectively. Of the 50 dairy farms, 66, 88, and 32% had TBC, CC and CPS counts, respectively, that exceeded the standard international limits for raw cow's milk intended for direct human consumption. TBC tended to increase as CC increased in bulk milk (r = 0.5). In the final regression model, increased TBC, CC and the contamination of farm bulk milk by S. aureus were significantly associated with dirty barns, dirty cows and soiled udder and teats. TBC was higher during the rainy season than during the dry season. The reported practice of washing teats with warm water significantly decreased CC and CPS. The occurrence of S. aureus was significantly (p < 0.05) higher in bulk farm milk (42%) than in pooled udder milk (37.3%), teat swabs (22.5%), milkers' hand swabs (18%), bulking bucket swabs (16.7%), milking container swabs (14%), and water for cleaning of udder and milkers' hands (10%). The questionnaire survey result showed widespred raw milk consumption habits, low level of training and poor hygienic milking practices. CONCLUSIONS This study revealed low-quality bulk farm milk with high bacterial counts and a high occurrence of S. aureus. This indicates the potential food safety risks due to consumption of raw milk or its products. This study suggests awareness creation to dairy farmers and the public on hygienic milk production and heat treatment of milk before consumption.
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Affiliation(s)
- Abiot Deddefo
- College of Agriculture and Environmental Sciences, Arsi University, P.O.Box 193, Asella, Ethiopia. .,College of Veterinary Medicine and Agriculture, Addis Ababa University, P.O.Box 34, Bishoftu, Ethiopia.
| | - Gezahegne Mamo
- College of Veterinary Medicine and Agriculture, Addis Ababa University, P.O.Box 34, Bishoftu, Ethiopia
| | - Minda Asfaw
- College of Agriculture and Environmental Sciences, Arsi University, P.O.Box 193, Asella, Ethiopia
| | - Kebede Amenu
- College of Veterinary Medicine and Agriculture, Addis Ababa University, P.O.Box 34, Bishoftu, Ethiopia.,Animal and Human Health Programme, International Livestock Research Institute (ILRI), P.O.Box 5689, Addis Ababa, Ethiopia
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Fernandes A, Ramos C, Monteiro V, Santos J, Fernandes P. Virulence Potential and Antibiotic Susceptibility of S. aureus Strains Isolated from Food Handlers. Microorganisms 2022; 10:2155. [PMID: 36363746 PMCID: PMC9696720 DOI: 10.3390/microorganisms10112155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 10/25/2022] [Accepted: 10/27/2022] [Indexed: 08/27/2023] Open
Abstract
Staphylococcus spp. are common members of the normal human flora. However, some Staphylococcus species are recognised as human pathogens due to the production of several virulence factors and enterotoxins that are particularly worrisome in food poisoning. Since many of Staphylococcal food poisoning outbreaks are typically associated with cross-contamination, the detection of S. aureus on food handlers was performed. Hand swabs from 167 food handlers were analysed for the presence of S. aureus. More than 11% of the samples were positive for S. aureus. All S. aureus strains were isolated and analysed for the presence of virulence and enterotoxin genes, namely, sea, seb, sec, sed, seg, sei, tsst-1 and pvl. The same strains were phenotypically characterised in terms of antibiotic susceptibility using the disc diffusion method and antimicrobial agents from 12 different classes. A low prevalence of antibiotic-resistant strains was found, with 55.6% of the strains being sensitive to all of the antimicrobial agents tested. However, a high prevalence of resistance to macrolides was found, with 44.4% of the strains showing resistance to erythromycin. At least one of the virulence or toxin genes was detected in 61.1% of the strains, and seg was the most prevalent toxin gene, being detected in 44.4% of the strains.
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Affiliation(s)
- Adriana Fernandes
- Escola Superior de Tecnologia e Gestão, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun’Álvares, 4900-347 Viana do Castelo, Portugal
| | - Carla Ramos
- Escola Superior de Tecnologia e Gestão, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun’Álvares, 4900-347 Viana do Castelo, Portugal
| | - Victor Monteiro
- Escola Superior de Tecnologia e Gestão, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun’Álvares, 4900-347 Viana do Castelo, Portugal
| | - Joana Santos
- Escola Superior de Tecnologia e Gestão, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun’Álvares, 4900-347 Viana do Castelo, Portugal
- CISAS, Escola Superior de Tecnologia e Gestão, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun’Álvares, 4900-347 Viana do Castelo, Portugal
| | - Paulo Fernandes
- Escola Superior de Tecnologia e Gestão, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun’Álvares, 4900-347 Viana do Castelo, Portugal
- CISAS, Escola Superior de Tecnologia e Gestão, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun’Álvares, 4900-347 Viana do Castelo, Portugal
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Gajewska J, Chajęcka-Wierzchowska W, Zadernowska A. Occurrence and Characteristics of Staphylococcus aureus Strains along the Production Chain of Raw Milk Cheeses in Poland. Molecules 2022; 27:molecules27196569. [PMID: 36235105 PMCID: PMC9573400 DOI: 10.3390/molecules27196569] [Citation(s) in RCA: 8] [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: 08/30/2022] [Revised: 09/29/2022] [Accepted: 09/30/2022] [Indexed: 11/06/2022] Open
Abstract
Cheeses produced from unpasteurized milk by traditional production methods may contain many groups of microorganisms, including Staphylococcus aureus. The aim of this study was to determine the occurrence of S. aureus in the artisanal cheese production chain from unpasteurized milk. We investigated the prevalence of S. aureus strains isolated from various stages of artisanal cheese of unpasteurized milk production from farms in the northeastern and southern parts of Poland and characterized them. Characterization included antimicrobial susceptibility by microbroth dilution and biofilm formation by in vitro assay. Among all strains, the presence of enterotoxigenic genes and genes involved with biofilm formation and antibiotic resistance were screened by PCR-based methods. A total of 180 samples were examined. A high percentage of strains were resistant to penicillin (54/58.1%) and tobramycin (32/34.4%). Some tested isolates also showed resistance to the macrolide class of antibiotics: azithromycin, clarithromycin, and erythromycin at 17/18.3%, 15/16.1%, and 21/22.6%, respectively. Among tested isolates, we also found phenotypic resistance to oxacillin (9/9.7%) and cefoxitin (12/12.9%). The blaZ gene encoding penicillin resistance was the most common gene encoding antibiotic resistance among the tested strains. All isolates showing phenotypic resistance to cefoxitin possessed the mecA gene. The study also evaluated the prevalence of biofilm-associated genes, with eno the most frequently associated gene. Eighty-nine out of 93 S. aureus isolates (95.7%) possessed at least one enterotoxin-encoding gene. The results of this study showed that production of raw milk cheeses may be a source of antibiotic resistance and virulent S. aureus. Our results suggest that artisanal cheese producers should better control production hygiene.
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Titouche Y, Akkou M, Houali K, Auvray F, Hennekinne JA. Role of milk and milk products in the spread of methicillin-resistant Staphylococcus aureus in the dairy production chain. J Food Sci 2022; 87:3699-3723. [PMID: 35894258 DOI: 10.1111/1750-3841.16259] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 06/09/2022] [Accepted: 06/28/2022] [Indexed: 11/29/2022]
Abstract
Milk and milk products can harbor a multiple varieties of microorganisms. Therefore, they can be an important source of foodborne pathogens, including multidrug-resistant bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) causes a wide spectrum of infections both in animals and humans. Over the last two decades, the presence of MRSA in foods and food-producing animals, including milk and milk products, has been frequently reported worldwide, raising public health concerns. In order to monitor and prevent foodborne MRSA contamination, it is necessary to understand their sources, the pheno/genotypic characteristics of the strains, and their transmission dynamics. In this review, studies conducted worldwide were summarized in order to assess the prevalence and diversity of MRSA circulating in milk and milk products. The risk factors for the occurrence of MRSA in milk and milk products were also discussed with preventive and control measures to avoid MRSA contamination in the dairy food chain.
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Affiliation(s)
- Yacine Titouche
- Laboratoire de Biochimie Analytique et Biotechnologie (LABAB), Université Mouloud Mammeri, Tizi Ouzou, Algérie
| | - Madjid Akkou
- Institut des Sciences Vétérinaires, Université Saad Dahlab, Blida, Algérie
| | - Karim Houali
- Laboratoire de Biochimie Analytique et Biotechnologie (LABAB), Université Mouloud Mammeri, Tizi Ouzou, Algérie
| | - Frédéric Auvray
- IRSD, INSERM, Université de Toulouse, INRAE, ENVT, UPS, Toulouse, France
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