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Chaudhary V, Kajla P, Lather D, Chaudhary N, Dangi P, Singh P, Pandiselvam R. Bacteriophages: a potential game changer in food processing industry. Crit Rev Biotechnol 2024:1-25. [PMID: 38228500 DOI: 10.1080/07388551.2023.2299768] [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: 02/25/2023] [Accepted: 10/03/2023] [Indexed: 01/18/2024]
Abstract
In the food industry, despite the widespread use of interventions such as preservatives and thermal and non-thermal processing technologies to improve food safety, incidences of foodborne disease continue to happen worldwide, prompting the search for alternative strategies. Bacteriophages, commonly known as phages, have emerged as a promising alternative for controlling pathogenic bacteria in food. This review emphasizes the potential applications of phages in biological sciences, food processing, and preservation, with a particular focus on their role as biocontrol agents for improving food quality and preservation. By shedding light on recent developments and future possibilities, this review highlights the significance of phages in the food industry. Additionally, it addresses crucial aspects such as regulatory status and safety concerns surrounding the use of bacteriophages. The inclusion of up-to-date literature further underscores the relevance of phage-based strategies in reducing foodborne pathogenic bacteria's presence in both food and the production environment. As we look ahead, new phage products are likely to be targeted against emerging foodborne pathogens. This will further advance the efficacy of approaches that are based on phages in maintaining the safety and security of food.
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Affiliation(s)
- Vandana Chaudhary
- Department of Dairy Technology, College of Dairy Science and Technology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India
| | - Priyanka Kajla
- Department of Food Technology, Guru Jambheshwar University of Science and Technology, Hisar, Haryana, India
| | - Deepika Lather
- Department of Veterinary Pathology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India
| | - Nisha Chaudhary
- Department of Food Science and Technology, College of Agriculture, Agriculture University, Jodhpur, Rajasthan, India
| | - Priya Dangi
- Department of Food and Nutrition and Food Technology, Institute of Home Economics, University of Delhi, New Delhi, India
| | - Punit Singh
- Department of Mechanical Engineering, Institute of Engineering and Technology, GLA University Mathura, Mathura, Uttar Pradesh, India
| | - Ravi Pandiselvam
- Physiology, Biochemistry and Post-Harvest Technology Division, ICAR -Central Plantation Crops Research Institute, Kasaragod, Kerala, India
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2
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Mohammed M, Casjens SR, Millard AD, Harrison C, Gannon L, Chattaway MA. Genomic analysis of Anderson typing phages of Salmonella Typhimrium: towards understanding the basis of bacteria-phage interaction. Sci Rep 2023; 13:10484. [PMID: 37380724 PMCID: PMC10307801 DOI: 10.1038/s41598-023-37307-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 06/20/2023] [Indexed: 06/30/2023] Open
Abstract
The Anderson phage typing scheme has been successfully used worldwide for epidemiological surveillance of Salmonella enterica serovar Typhimurium. Although the scheme is being replaced by whole genome sequence subtyping methods, it can provide a valuable model system for study of phage-host interaction. The phage typing scheme distinguishes more than 300 definitive types of Salmonella Typhimurium based on their patterns of lysis to a unique collection of 30 specific Salmonella phages. In this study, we sequenced the genomes of 28 Anderson typing phages of Salmonella Typhimurium to begin to characterize the genetic determinants that are responsible for the differences in these phage type profiles. Genomic analysis of typing phages reveals that Anderson phages can be classified into three different groups, the P22-like, ES18-like and SETP3-like clusters. Most Anderson phages are short tailed P22-like viruses (genus Lederbergvirus); but phages STMP8 and STMP18 are very closely related to the lambdoid long tailed phage ES18, and phages STMP12 and STMP13 are related to the long noncontractile tailed, virulent phage SETP3. Most of these typing phages have complex genome relationships, but interestingly, two phage pairs STMP5 and STMP16 as well as STMP12 and STMP13 differ by a single nucleotide. The former affects a P22-like protein involved in DNA passage through the periplasm during its injection, and the latter affects a gene whose function is unknown. Using the Anderson phage typing scheme would provide insights into phage biology and the development of phage therapy for the treatment of antibiotic resistant bacterial infections.
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Affiliation(s)
- Manal Mohammed
- Genomics and Infectious Diseases Research Group, School of Life Sciences, University of Westminster, 115 New Cavendish Street, London, W1W 6UW, UK.
| | - Sherwood R Casjens
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, University of Utah, Salt Lake City, UT, 84112, USA
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Andrew D Millard
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester, LE1 7RH, UK
| | - Christian Harrison
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester, LE1 7RH, UK
| | - Lucy Gannon
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester, LE1 7RH, UK
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Abdelsattar AS, Dawoud A, Makky S, Nofal R, Aziz RK, El-Shibiny A. Bacteriophages: from isolation to application. Curr Pharm Biotechnol 2021; 23:337-360. [PMID: 33902418 DOI: 10.2174/1389201022666210426092002] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 01/29/2021] [Accepted: 03/11/2021] [Indexed: 11/22/2022]
Abstract
Bacteriophages are considered as a potential alternative to fight pathogenic bacteria during the antibiotic resistance era. With their high specificity, they are being widely used in various applications: medicine, food industry, agriculture, animal farms, biotechnology, diagnosis, etc. Many techniques have been designed by different researchers for phage isolation, purification, and amplification, each of which has strengths and weaknesses. However, all aim at having a reasonably pure phage sample that can be further characterized. Phages can be characterized based on their physiological, morphological or inactivation tests. Microscopy, in particular, has opened a wide gate not only for visualizing phage morphological structure, but also for monitoring biochemistry and behavior. Meanwhile, computational analysis of phage genomes provides more details about phage history, lifestyle, and potential for toxigenic or lysogenic conversion, which translate to safety in biocontrol and phage therapy applications. This review summarizes phage application pipelines at different levels and addresses specific restrictions and knowledge gaps in the field. Recently developed computational approaches, which are used in phage genome analysis, are critically assessed. We hope that this assessment provides researchers with useful insights for selection of suitable approaches for Phage-related research aims and applications.
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Affiliation(s)
- Abdallah S Abdelsattar
- Center for Microbiology and Phage Therapy, Zewail City of Science and Technology, October Gardens, 6th of October City, Giza, 12578. Egypt
| | - Alyaa Dawoud
- Center for Microbiology and Phage Therapy, Zewail City of Science and Technology, October Gardens, 6th of October City, Giza, 12578. Egypt
| | - Salsabil Makky
- Center for Microbiology and Phage Therapy, Zewail City of Science and Technology, October Gardens, 6th of October City, Giza, 12578. Egypt
| | - Rana Nofal
- Center for Microbiology and Phage Therapy, Zewail City of Science and Technology, October Gardens, 6th of October City, Giza, 12578. Egypt
| | - Ramy K Aziz
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Qasr El-Ainy St, Cairo. Egypt
| | - Ayman El-Shibiny
- Center for Microbiology and Phage Therapy, Zewail City of Science and Technology, October Gardens, 6th of October City, Giza, 12578. Egypt
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Mohammed M, Orzechowska B. Characterisation of Phage Susceptibility Variation in Salmonellaenterica Serovar Typhimurium DT104 and DT104b. Microorganisms 2021; 9:microorganisms9040865. [PMID: 33920555 PMCID: PMC8073726 DOI: 10.3390/microorganisms9040865] [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: 03/08/2021] [Revised: 04/06/2021] [Accepted: 04/13/2021] [Indexed: 02/07/2023] Open
Abstract
The surge in mortality and morbidity rates caused by multidrug-resistant (MDR) bacteria prompted a renewal of interest in bacteriophages (phages) as clinical therapeutics and natural biocontrol agents. Nevertheless, bacteria and phages are continually under the pressure of the evolutionary phage–host arms race for survival, which is mediated by co-evolving resistance mechanisms. In Anderson phage typing scheme of Salmonella Typhimurium, the epidemiologically related definitive phage types, DT104 and DT104b, display significantly different phage susceptibility profiles. This study aimed to characterise phage resistance mechanisms and genomic differences that may be responsible for the divergent phage reaction patterns in S. Typhimurium DT104 and DT104b using whole genome sequencing (WGS). The analysis of intact prophages, restriction–modification systems (RMS), plasmids and clustered regularly interspaced short palindromic repeats (CRISPRs), as well as CRISPR-associated proteins, revealed no unique genetic determinants that might explain the variation in phage susceptibility among the two phage types. Moreover, analysis of genes coding for potential phage receptors revealed no differences among DT104 and DT104b strains. However, the findings propose the need for experimental assessment of phage-specific receptors on the bacterial cell surface and analysis of bacterial transcriptome using RNA sequencing which will explain the differences in bacterial susceptibility to phages. Using Anderson phage typing scheme of Salmonella Typhimurium for the study of bacteria-phage interaction will help improving our understanding of host–phage interactions which will ultimately lead to the development of phage-based technologies, enabling effective infection control.
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Traditional Salmonella Typhimurium typing tools (phage typing and MLVA) are sufficient to resolve well-defined outbreak events only. Food Microbiol 2019; 84:103237. [PMID: 31421774 DOI: 10.1016/j.fm.2019.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 05/10/2019] [Accepted: 06/02/2019] [Indexed: 11/22/2022]
Abstract
Between 1991 and 2014 the per capita notification rate of salmonellosis in Australia increased from 31.9 to 69.7 cases per 100,000 people. Salmonella Typhimurium accounted for nearly half the human cases until the end of 2014. In this study, we used cluster analysis tools to compare S. Typhimurium isolates from a chicken-meat study with those reported to the National Enteric Pathogen Surveillance System (NEPSS) from the coincident human and non-human populations. There was limited phage type diversity within all populations and a lack of specificity of MLVA profiling within phage types. The chicken-meat study isolates were not significantly clustered with the human cases and at least 7 non-human sources, based on typing profiles (PT/MLVA combination), could be implicated as a source of human cases during the same period. In the absence of a strong surveillance system representative of all putative sources, MLVA and phage typing alone or in combination are insufficient to identify the source of human cases.
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Mellor KC, Petrovska L, Thomson NR, Harris K, Reid SWJ, Mather AE. Antimicrobial Resistance Diversity Suggestive of Distinct Salmonella Typhimurium Sources or Selective Pressures in Food-Production Animals. Front Microbiol 2019; 10:708. [PMID: 31031720 PMCID: PMC6473194 DOI: 10.3389/fmicb.2019.00708] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 03/21/2019] [Indexed: 11/13/2022] Open
Abstract
Salmonella enterica subsp. enterica serovar Typhimurium is a common cause of enterocolitis in humans globally, with multidrug resistant (MDR) strains posing an enhanced threat. S. Typhimurium is also a pathogen in food-production animals, and these populations can act as reservoirs of the bacterium. Therefore, surveillance and control measures within food-production animal populations are of importance both to animal and human health and have the potential to be enhanced though improved understanding of the epidemiology of S. Typhimurium within and between food-production animal populations. Here, data from Scotland and national surveillance England and Wales data for isolates from cattle (n = 1115), chickens (n = 248) and pigs (n = 2174) collected between 2003 and 2014 were analyzed. Ecological diversity analyses and rarefaction curves were used to compare the diversity of observed antimicrobial resistance (AMR) profiles between the host species, and within host species populations. Higher AMR profile diversity was observed in isolates from pigs compared to chickens across diversity measures and isolates from cattle for three of four diversity measures. Variation in AMR profile diversity between production sectors was noted, with higher AMR diversity of isolates from broiler compared to layer chickens, breeder compared to rearer and finisher pigs and beef compared to dairy cattle. Findings indicate variation in AMR profile diversity both within and between food-production animal host species. These observations suggest alternate sources of AMR bacteria and/or variation in selective evolutionary pressures within and between food-production animal host species populations.
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Affiliation(s)
- Kate C. Mellor
- Royal Veterinary College, Hatfield, United Kingdom
- London School of Hygiene & Tropical Medicine, London, United Kingdom
| | | | - Nicholas R. Thomson
- London School of Hygiene & Tropical Medicine, London, United Kingdom
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Kate Harris
- Animal and Plant Health Agency, Weybridge, United Kingdom
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Epidemiological Surveillance and Typing Methods to Track Antibiotic Resistant Strains Using High Throughput Sequencing. Methods Mol Biol 2018; 1520:331-356. [PMID: 27873262 DOI: 10.1007/978-1-4939-6634-9_20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
High-Throughput Sequencing (HTS) technologies transformed the microbial typing and molecular epidemiology field by providing the cost-effective ability for researchers to probe draft genomes, not only for epidemiological markers but also for antibiotic resistance and virulence determinants. In this chapter, we provide protocols for the analysis of HTS data for the determination of multilocus sequence typing (MLST) information and for determining presence or absence of antibiotic resistance genes.
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Ferrari RG, Panzenhagen PHN, Conte-Junior CA. Phenotypic and Genotypic Eligible Methods for Salmonella Typhimurium Source Tracking. Front Microbiol 2017; 8:2587. [PMID: 29312260 PMCID: PMC5744012 DOI: 10.3389/fmicb.2017.02587] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 12/12/2017] [Indexed: 11/13/2022] Open
Abstract
Salmonellosis is one of the most common causes of foodborne infection and a leading cause of human gastroenteritis. Throughout the last decade, Salmonella enterica serotype Typhimurium (ST) has shown an increase report with the simultaneous emergence of multidrug-resistant isolates, as phage type DT104. Therefore, to successfully control this microorganism, it is important to attribute salmonellosis to the exact source. Studies of Salmonella source attribution have been performed to determine the main food/food-production animals involved, toward which, control efforts should be correctly directed. Hence, the election of a ST subtyping method depends on the particular problem that efforts must be directed, the resources and the data available. Generally, before choosing a molecular subtyping, phenotyping approaches such as serotyping, phage typing, and antimicrobial resistance profiling are implemented as a screening of an investigation, and the results are computed using frequency-matching models (i.e., Dutch, Hald and Asymmetric Island models). Actually, due to the advancement of molecular tools as PFGE, MLVA, MLST, CRISPR, and WGS more precise results have been obtained, but even with these technologies, there are still gaps to be elucidated. To address this issue, an important question needs to be answered: what are the currently suitable subtyping methods to source attribute ST. This review presents the most frequently applied subtyping methods used to characterize ST, analyses the major available microbial subtyping attribution models and ponders the use of conventional phenotyping methods, as well as, the most applied genotypic tools in the context of their potential applicability to investigates ST source tracking.
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Affiliation(s)
- Rafaela G. Ferrari
- Molecular and Analytical Laboratory Center, Department of Food Technology, Faculty of Veterinary, Universidade Federal Fluminense, Niterói, Brazil
- Food Science Program, Chemistry Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Pedro H. N. Panzenhagen
- Molecular and Analytical Laboratory Center, Department of Food Technology, Faculty of Veterinary, Universidade Federal Fluminense, Niterói, Brazil
- Food Science Program, Chemistry Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Carlos A. Conte-Junior
- Molecular and Analytical Laboratory Center, Department of Food Technology, Faculty of Veterinary, Universidade Federal Fluminense, Niterói, Brazil
- Food Science Program, Chemistry Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- National Institute of Health Quality Control, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
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Ariel E, Freeman AB, Elliott E, Wirth W, Mashkour N, Scott J. An unusual mortality event in Johnstone River snapping turtles Elseya irwini (Johnstone) in Far North Queensland, Australia. Aust Vet J 2017; 95:355-361. [PMID: 28948624 DOI: 10.1111/avj.12627] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 10/21/2016] [Accepted: 10/27/2016] [Indexed: 11/29/2022]
Abstract
BACKGROUND An unusual mortality event in Johnstone River snapping turtles (Elseya irwini) in Far North Queensland, Australia, occurred during the summer months of December 2014 and January 2015. We report the data collected during the mortality event, including counts of sick and dead animals, clinical appearance and one necropsy. OUTBREAK DESCRIPTION Moribund animals appeared lethargic with variable degrees of necrotising dermatitis. Postmortem investigation of one freshly dead animal revealed bacterial and fungal involvement in the skin lesions as well as multifocal fibrinous hepatitis and splenitis and necrotising enteritis with vascular thrombosis. Aeromonas hydrophila was isolated from liver, spleen and skin lesions. All samples tested negative for ranavirus, and water and soil testing for environmental contaminants were negative. All affected E. irwini either died or were euthanased and no other species of animals in the river were affected. CONCLUSION Aeromonas hydrophila is ubiquitous in the freshwater environment and although it caused septicaemia in the one individual that was submitted for laboratory diagnosis, the primary aetiology of the outbreak may not have been identified.
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Affiliation(s)
- E Ariel
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - A B Freeman
- Threatened Species Unit, Queensland Department of Environment and Heritage Protection, Atherton, Queensland, Australia
| | - E Elliott
- AusPhage, Rasmussen, Queensland, Australia
| | - W Wirth
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - N Mashkour
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - J Scott
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland 4811, Australia
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Dave J, Warburton F, Freedman J, de Pinna E, Grant K, Sefton A, Crawley-Boevey E, Godbole G, Holliman R, Balasegaram S. What were the risk factors and trends in antimicrobial resistance for enteric fever in London 2005–2012? J Med Microbiol 2017; 66:698-705. [DOI: 10.1099/jmm.0.000484] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Jayshree Dave
- Public Health Laboratory London, Public Health England, London, UK
| | - Fiona Warburton
- Statistics, Modelling and Economics Department, Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK
| | - Joanne Freedman
- Travel and Migrant Health Section, Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK
| | - Elizabeth de Pinna
- Gastrointestinal Bacteria Reference Unit, Public Health England, London, UK
| | - Kathie Grant
- Gastrointestinal Bacteria Reference Unit, Public Health England, London, UK
| | - Armine Sefton
- Centre of Immunology and Infectious Disease, Blizard Institute, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, London, UK
| | | | - Gauri Godbole
- Gastrointestinal Bacteria Reference Unit, Public Health England, London, UK
| | - Richard Holliman
- Public Health Laboratory London, Public Health England, London, UK
| | - Sooria Balasegaram
- Field Epidemiology Services South East and London, Public Health England, London, UK
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11
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Prevalence and antimicrobial resistance ofSalmonellaserovars isolated from poultry in Ghana. Epidemiol Infect 2016; 144:3288-3299. [DOI: 10.1017/s0950268816001126] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SUMMARYPoultry are possible sources of non-typhoidalSalmonellaserovars which may cause foodborne human disease. We conducted a cross-sectional study to determine the prevalence ofSalmonellaserovars in egg-laying hens and broilers at the farm level and their susceptibility to antimicrobials commonly used in the poultry industry in Ghana. Sampling of faeces by a sock method (n= 75), dust (n= 75), feed (n= 10) and drinking water (n= 10) was performed at 75 commercial egg-laying and broiler farms in two regions of Ghana and skin neck (n= 30) at a local slaughterhouse from broilers representing different flocks.Salmonellawas detected in 94/200 (47%) samples with an overall flock prevalence of 44·0%. Sixteen different serovars were identified withS. Kentucky (18·1%),S. Nima (12·8%),S. Muenster (10·6%),S. Enteritidis (10·6%) andS. Virchow (9·6 %) the most prevalent types. The predominant phage type ofS. Enteritidis was PT1. All strains were susceptible to cefotaxime, ceftazidime and cefoxitin. Fifty-seven (60·6%) strains were resistant to one or more of the remaining nine antimicrobials tested by disk diffusion, of which 23 (40·4%) showed multi-resistance (resistance to ⩾3 classes of antimicrobials). Of the resistant strains (n= 57), the most significant were to nalidixic acid (89·5%), tetracycline (80·7%), ciprofloxacin (64·9%), sulfamethazole (42·1%), trimethoprim (29·8%) and ampicillin (26·3%). AllS.Kentucky strains were resistant to more than two antimicrobials and shared common resistance to nalidixic acid or ciprofloxacin and tetracycline, often in combinations with other antimicrobials. PFGE analysis usingXbaI ofS. Kentucky demonstrated one dominant clone in the country. In conclusion, poultry produced in Ghana has a high prevalence of multi-resistantSalmonellaand the common finding of clonalS.Kentucky in the Kumasi area warrants further investigations into the epidemiology of this serovar. There is an urgent need for surveillance and control programmes onSalmonellaand use of antimicrobials in the Ghanaian poultry industry to protect the health of consumers.
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12
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Baltrus DA. Divorcing Strain Classification from Species Names. Trends Microbiol 2016; 24:431-439. [PMID: 26947794 DOI: 10.1016/j.tim.2016.02.004] [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: 12/16/2015] [Revised: 01/29/2016] [Accepted: 02/04/2016] [Indexed: 02/01/2023]
Abstract
Confusion about strain classification and nomenclature permeates modern microbiology. Although taxonomists have traditionally acted as gatekeepers of order, the numbers of, and speed at which, new strains are identified has outpaced the opportunity for professional classification for many lineages. Furthermore, the growth of bioinformatics and database-fueled investigations have placed metadata curation in the hands of researchers with little taxonomic experience. Here I describe practical challenges facing modern microbial taxonomy, provide an overview of complexities of classification for environmentally ubiquitous taxa like Pseudomonas syringae, and emphasize that classification can be independent of nomenclature. A move toward implementation of relational classification schemes based on inherent properties of whole genomes could provide sorely needed continuity in how strains are referenced across manuscripts and data sets.
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Affiliation(s)
- David A Baltrus
- School of Plant Sciences, University of Arizona, Tucson, AZ, USA.
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13
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Thompson SM, Johnson CP, Lu AY, Frampton RA, Sullivan KL, Fiers MWEJ, Crowhurst RN, Pitman AR, Scott IAW, Wen A, Gudmestad NC, Smith GR. Genomes of 'Candidatus Liberibacter solanacearum' Haplotype A from New Zealand and the United States Suggest Significant Genome Plasticity in the Species. PHYTOPATHOLOGY 2015; 105:863-871. [PMID: 25822188 DOI: 10.1094/phyto-12-14-0363-fi] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
'Candidatus Liberibacter solanacearum' contains two solanaceous crop-infecting haplotypes, A and B. Two haplotype A draft genomes were assembled and compared with ZC1 (haplotype B), revealing inversion and relocation genomic rearrangements, numerous single-nucleotide polymorphisms, and differences in phage-related regions. Differences in prophage location and sequence were seen both within and between haplotype comparisons. OrthoMCL and BLAST analyses identified 46 putative coding sequences present in haplotype A that were not present in haplotype B. Thirty-eight of these loci were not found in sequences from other Liberibacter spp. Quantitative polymerase chain reaction (qPCR) assays designed to amplify sequences from 15 of these loci were screened against a panel of 'Ca. L. solanacearum'-positive samples to investigate genetic diversity. Seven of the assays demonstrated within-haplotype diversity; five failed to amplify loci in at least one haplotype A sample while three assays produced amplicons from some haplotype B samples. Eight of the loci assays showed consistent A-B differentiation. Differences in genome arrangements, prophage, and qPCR results suggesting locus diversity within the haplotypes provide more evidence for genetic complexity in this emerging bacterial species.
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Affiliation(s)
- Sarah M Thompson
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Chris P Johnson
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Ashley Y Lu
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Rebekah A Frampton
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Kerry L Sullivan
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Mark W E J Fiers
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Ross N Crowhurst
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Andrew R Pitman
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Ian A W Scott
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Aimin Wen
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Neil C Gudmestad
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
| | - Grant R Smith
- First, third, fourth, fifth, sixth, eighth, ninth, and twelfth authors: The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, New Zealand; first, third, fourth, fifth, eighth, ninth, and twelfth authors: Plant Biosecurity Cooperative Research Centre, Canberra, ACT 2617, Australia; second, tenth, and eleventh authors: Department of Plant Pathology, North Dakota State University, Fargo 58108; and seventh author: The New Zealand Institute for Plant & Food Research Limited, Mt Albert 1025, New Zealand
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14
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Cowley LA, Beckett SJ, Chase-Topping M, Perry N, Dallman TJ, Gally DL, Jenkins C. Analysis of whole genome sequencing for the Escherichia coli O157:H7 typing phages. BMC Genomics 2015; 16:271. [PMID: 25887960 PMCID: PMC4429339 DOI: 10.1186/s12864-015-1470-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 03/17/2015] [Indexed: 11/17/2022] Open
Abstract
Background Shiga toxin producing Escherichia coli O157 can cause severe bloody diarrhea and haemolytic uraemic syndrome. Phage typing of E. coli O157 facilitates public health surveillance and outbreak investigations, certain phage types are more likely to occupy specific niches and are associated with specific age groups and disease severity. The aim of this study was to analyse the genome sequences of 16 (fourteen T4 and two T7) E. coli O157 typing phages and to determine the genes responsible for the subtle differences in phage type profiles. Results The typing phages were sequenced using paired-end Illumina sequencing at The Genome Analysis Centre and the Animal Health and Veterinary Laboratories Agency and bioinformatics programs including Velvet, Brig and Easyfig were used to analyse them. A two-way Euclidian cluster analysis highlighted the associations between groups of phage types and typing phages. The analysis showed that the T7 typing phages (9 and 10) differed by only three genes and that the T4 typing phages formed three distinct groups of similar genomic sequences: Group 1 (1, 8, 11, 12 and 15, 16), Group 2 (3, 6, 7 and 13) and Group 3 (2, 4, 5 and 14). The E. coli O157 phage typing scheme exhibited a significantly modular network linked to the genetic similarity of each group showing that these groups are specialised to infect a subset of phage types. Conclusion Sequencing the typing phage has enabled us to identify the variable genes within each group and to determine how this corresponds to changes in phage type. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1470-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lauren A Cowley
- Gastrointestinal Bacteria Reference Unit, Public Health England, 61 Colindale Ave, London, NW9 5HT, UK.
| | - Stephen J Beckett
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Laver Building, North Park Road, Exeter, EX4 4QE, UK.
| | - Margo Chase-Topping
- Division of Immunity and Infection, The Roslin Institute, R(D)VS, University of Edinburgh, Edinburgh, EH25 9RG, UK.
| | - Neil Perry
- Gastrointestinal Bacteria Reference Unit, Public Health England, 61 Colindale Ave, London, NW9 5HT, UK.
| | - Tim J Dallman
- Gastrointestinal Bacteria Reference Unit, Public Health England, 61 Colindale Ave, London, NW9 5HT, UK.
| | - David L Gally
- Division of Immunity and Infection, The Roslin Institute, R(D)VS, University of Edinburgh, Edinburgh, EH25 9RG, UK.
| | - Claire Jenkins
- Gastrointestinal Bacteria Reference Unit, Public Health England, 61 Colindale Ave, London, NW9 5HT, UK.
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15
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Development of a new molecular subtyping tool for Salmonella enterica serovar Enteritidis based on single nucleotide polymorphism genotyping using PCR. J Clin Microbiol 2014; 52:4275-85. [PMID: 25297333 DOI: 10.1128/jcm.01410-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lack of a sufficiently discriminatory molecular subtyping tool for Salmonella enterica serovar Enteritidis has hindered source attribution efforts and impeded regulatory actions required to disrupt its food-borne transmission. The underlying biological reason for the ineffectiveness of current molecular subtyping tools such as pulsed-field gel electrophoresis (PFGE) and phage typing appears to be related to the high degree of clonality of S. Enteritidis. By interrogating the organism's genome, we previously identified single nucleotide polymorphisms (SNP) distributed throughout the chromosome and have designed a highly discriminatory PCR-based SNP typing test based on 60 polymorphic loci. The application of the SNP-PCR method to DNA samples from S. Enteritidis strains (n = 55) obtained from a variety of sources has led to the differentiation and clustering of the S. Enteritidis isolates into 12 clades made up of 2 to 9 isolates per clade. Significantly, the SNP-PCR assay was able to further differentiate predominant PFGE types (e.g., XAI.0003) and phage types (e.g., phage type 8) into smaller subsets. The SNP-PCR subtyping test proved to be an accurate, precise, and quantitative tool for evaluating the relationships among the S. Enteritidis isolates tested in this study and should prove useful for clustering related S. Enteritidis isolates involved in outbreaks.
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16
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Barco L, Barrucci F, Olsen JE, Ricci A. Salmonella source attribution based on microbial subtyping. Int J Food Microbiol 2013; 163:193-203. [PMID: 23562696 DOI: 10.1016/j.ijfoodmicro.2013.03.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2012] [Revised: 01/20/2013] [Accepted: 03/02/2013] [Indexed: 10/27/2022]
Abstract
Source attribution of cases of food-borne disease represents a valuable tool for identifying and prioritizing effective food-safety interventions. Microbial subtyping is one of the most common methods to infer potential sources of human food-borne infections. So far, Salmonella microbial subtyping source attribution models have been implemented by using serotyping and phage-typing data. Molecular-based methods may prove to be similarly valuable in the future, as already demonstrated for other food-borne pathogens like Campylobacter. This review assesses the state of the art concerning Salmonella source attribution through microbial subtyping approach. It summarizes the available microbial subtyping attribution models and discusses the use of conventional phenotypic typing methods, as well as of the most commonly applied molecular typing methods in the European Union (EU) laboratories in the context of their potential applicability for Salmonella source attribution studies.
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Affiliation(s)
- Lisa Barco
- OIE, National Reference Laboratory for Salmonella, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, Padova, 35020 Legnaro, Italy
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17
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Achtman M, Wain J, Weill FX, Nair S, Zhou Z, Sangal V, Krauland MG, Hale JL, Harbottle H, Uesbeck A, Dougan G, Harrison LH, Brisse S. Multilocus sequence typing as a replacement for serotyping in Salmonella enterica. PLoS Pathog 2012; 8:e1002776. [PMID: 22737074 PMCID: PMC3380943 DOI: 10.1371/journal.ppat.1002776] [Citation(s) in RCA: 448] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 05/10/2012] [Indexed: 12/15/2022] Open
Abstract
Salmonella enterica subspecies enterica is traditionally subdivided into serovars by serological and nutritional characteristics. We used Multilocus Sequence Typing (MLST) to assign 4,257 isolates from 554 serovars to 1092 sequence types (STs). The majority of the isolates and many STs were grouped into 138 genetically closely related clusters called eBurstGroups (eBGs). Many eBGs correspond to a serovar, for example most Typhimurium are in eBG1 and most Enteritidis are in eBG4, but many eBGs contained more than one serovar. Furthermore, most serovars were polyphyletic and are distributed across multiple unrelated eBGs. Thus, serovar designations confounded genetically unrelated isolates and failed to recognize natural evolutionary groupings. An inability of serotyping to correctly group isolates was most apparent for Paratyphi B and its variant Java. Most Paratyphi B were included within a sub-cluster of STs belonging to eBG5, which also encompasses a separate sub-cluster of Java STs. However, diphasic Java variants were also found in two other eBGs and monophasic Java variants were in four other eBGs or STs, one of which is in subspecies salamae and a second of which includes isolates assigned to Enteritidis, Dublin and monophasic Paratyphi B. Similarly, Choleraesuis was found in eBG6 and is closely related to Paratyphi C, which is in eBG20. However, Choleraesuis var. Decatur consists of isolates from seven other, unrelated eBGs or STs. The serological assignment of these Decatur isolates to Choleraesuis likely reflects lateral gene transfer of flagellar genes between unrelated bacteria plus purifying selection. By confounding multiple evolutionary groups, serotyping can be misleading about the disease potential of S. enterica. Unlike serotyping, MLST recognizes evolutionary groupings and we recommend that Salmonella classification by serotyping should be replaced by MLST or its equivalents. Microbiologists have used serological and nutritional characteristics to subdivide pathogenic bacteria for nearly 100 years. These subdivisions in Salmonella enterica are called serovars, some of which are thought to be associated with particular diseases and epidemiology. We used MultiLocus Sequence-based Typing (MLST) to identify clusters of S. enterica isolates that are related by evolutionary descent. Some clusters correspond to serovars on a one to one basis. But many clusters include multiple serovars, which is of public health significance, and most serovars span multiple, unrelated clusters. Despite its broad usage, serological typing of S. enterica has resulted in confusing systematics, with a few exceptions. We recommend that serotyping for strain discrimination of S. enterica be replaced by a DNA-based method, such as MLST. Serotyping and other non-sequence based typing methods are routinely used for detecting outbreaks and to support public health responses. Moving away from these methods will require a major shift in thinking by public health microbiology laboratories as well as national and international agencies. However, a transition to the routine use of MLST, supplemented where appropriate by even more discriminatory sequence-based typing methods based on entire genomes, will provide a clearer picture of long-term transmission routes of Salmonella, facilitate data transfer and support global control measures.
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Affiliation(s)
- Mark Achtman
- Environmental Research Institute and Department of Microbiology, University College Cork, Cork, Ireland.
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Barco L, Mancin M, Ruffa M, Saccardin C, Minorello C, Zavagnin P, Lettini A, Olsen JE, Ricci A. Application of the Random Forest Method to Analyse Epidemiological and Phenotypic Characteristics ofSalmonella4,[5],12:i:- andSalmonellaTyphimurium Strains. Zoonoses Public Health 2012; 59:505-12. [DOI: 10.1111/j.1863-2378.2012.01487.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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A long-lasting outbreak of Salmonella Typhimurium U323 associated with several pork products, Denmark, 2010. Epidemiol Infect 2012; 141:260-8. [PMID: 22717213 DOI: 10.1017/s0950268812000702] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
This paper shows that control of foodborne disease outbreaks may be challenging even after establishing the source of infection. An outbreak of Salmonella Typhimurium U323 infections occurred in Denmark from March to September 2010, involving 172 cases. Before the detection of human cases, several positive isolates of the outbreak strain had been found in a particular pig slaughterhouse and thus early traceback, investigation and control measures were possible. Several batches of pork and pork products were recalled and the slaughterhouse was closed twice for disinfection. No single common food item was identified as the outbreak source, but repeated isolation of the outbreak strain from the slaughterhouse environment and in pork and products as well as patient interviews strongly suggested different pork products as the source of infection. Furthermore, a matched case-control study identified a specific ready-to-eat spreadable pork sausage (teewurst) as the source of a sub-outbreak (matched odds ratio 17, 95% confidence interval 2·1-130).
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Chenu JW, Cox JM, Pavic A. Classification of Salmonella enterica serotypes from Australian poultry using repetitive sequence-based PCR. J Appl Microbiol 2011; 112:185-96. [PMID: 21981579 DOI: 10.1111/j.1365-2672.2011.05172.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS To evaluate a semi-automated repetitive extragenic palindromic sequence-based PCR (rep-PCR) system for the classification of Salmonella serotypes from Australian poultry. METHODS AND RESULTS Using a DNA fingerprint library within the DiversiLab(®) System, four separate databases were constructed (serogroup B, C, E and Other). These databases contained 483 serologically confirmed (reference laboratory) Salmonella isolates. A blinded set of Salmonella cultures (n = 155) were typed by rep-PCR, matched against the internal library and compared with traditional serotyping. The predicted (Kullback-Leibler) serotype of 143 (92·3%) isolates matched traditional typing (P < 0·05). Of the 12 (7·7%) remaining isolates, ten (6·5%) resulted in 'No Match', one (0·65%) was incorrectly matched to the library (Salm. subsp 1 ser 4,12:-:-), and the other (0·65%) was referenced as Salm. ser. Sofia, whereas rep-PCR and in-house serotyping concurred as Salmonella serovar Typhimurium. Financial analysis showed higher material cost (215%) and a lower labour component (47·5%) for rep-PCR compared with serotyping. CONCLUSION The DiversiLab(®) System, with serogroup databases, was successfully implemented as an adjunct for reference serotyping of Salmonella enterica. SIGNIFICANCE AND IMPACT OF THE STUDY The DiversiLab(®) System platform is a cost-effective and easy-to-use system, which can putatively determine Salmonella enterica serotypes within a few hours.
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Affiliation(s)
- J W Chenu
- Birling Avian Laboratories, Bringelly, NSW, Australia
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21
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Methodologies for Salmonella enterica subsp. enterica subtyping: gold standards and alternatives. Appl Environ Microbiol 2011; 77:7877-85. [PMID: 21856826 DOI: 10.1128/aem.05527-11] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
For more than 80 years, subtyping of Salmonella enterica has been routinely performed by serotyping, a method in which surface antigens are identified based on agglutination reactions with specific antibodies. The serotyping scheme, which is continuously updated as new serovars are discovered, has generated over time a data set of the utmost significance, allowing long-term epidemiological surveillance of Salmonella in the food chain and in public health control. Conceptually, serotyping provides no information regarding the phyletic relationships inside the different Salmonella enterica subspecies. In epidemiological investigations, identification and tracking of salmonellosis outbreaks require the use of methods that can fingerprint the causative strains at a taxonomic level far more specific than the one achieved by serotyping. During the last 2 decades, alternative methods that could successfully identify the serovar of a given strain by probing its DNA have emerged, and molecular biology-based methods have been made available to address phylogeny and fingerprinting issues. At the same time, accredited diagnostics have become increasingly generalized, imposing stringent methodological requirements in terms of traceability and measurability. In these new contexts, the hand-crafted character of classical serotyping is being challenged, although it is widely accepted that classification into serovars should be maintained. This review summarizes and discusses modern typing methods, with a particular focus on those having potential as alternatives for classical serotyping or for subtyping Salmonella strains at a deeper level.
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Bugarel M, Granier SA, Weill FX, Fach P, Brisabois A. A multiplex real-time PCR assay targeting virulence and resistance genes in Salmonella enterica serotype Typhimurium. BMC Microbiol 2011; 11:151. [PMID: 21707966 PMCID: PMC3150258 DOI: 10.1186/1471-2180-11-151] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 06/27/2011] [Indexed: 12/02/2022] Open
Abstract
Background Typhimurium is the main serotype of Salmonella enterica subsp. enterica implicated in food-borne diseases worldwide. This study aimed to detect the prevalence of ten markers combined in a macro-array based on multiplex real-time PCR. We targeted characteristic determinants located on pathogenicity islands (SPI-2 to -5, virulence plasmid pSLT and Salmonella genomic island 1 (SGI1)) as well as a specific 16S-23S rRNA intergenic spacer sequence of definitive type 104 (DT104). To investigate antimicrobial resistance, the study also targeted the presence of genes involved in sulfonamide (sul1) and beta-lactam (blaTEM) resistance. Finally, the intI1 determinant encoding integrase from class 1 integron was also investigated. Results A total of 538 unrelated S. Typhimurium strains isolated between 1999 and 2009 from various sources, including food animals, food products, human and environmental samples were studied. Based on the combined presence or absence of these markers, we distinguished 34 different genotypes, including three major genotypes encountered in 75% of the studied strains, Although SPI determinants were almost always detected, SGI1, intI1, sul1 and blaTEM determinants were found 47%, 52%, 54% and 12% of the time respectively, varying according to isolation source. Low-marker patterns were most often detected in poultry sources whereas full-marker patterns were observed in pig, cattle and human sources. Conclusion The GeneDisc® assay developed in this study madeit easier to explore variability within serotype Typhimurium by analyzing ten relevant gene determinants in a large collection of strains. This real-time multiplex method constitutes a valuable tool for strains characterization on epidemiological purposes.
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Affiliation(s)
- Marie Bugarel
- French Agency for Food, Environmental and Occupational Health Safety (ANSES) Laboratory for Food Safety, Maisons-Alfort Cedex, France
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Petersen RF, Litrup E, Larsson JT, Torpdahl M, Sørensen G, Müller L, Nielsen EM. Molecular characterization of Salmonella Typhimurium highly successful outbreak strains. Foodborne Pathog Dis 2011; 8:655-61. [PMID: 21381921 DOI: 10.1089/fpd.2010.0683] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Three large clusters of Salmonella Typhimurium infections in Denmark in 2008 and 2009 were defined by multilocus variable number of tandem repeat analysis (MLVA). One of these proved to be the hereto largest Danish cluster of salmonellosis with 1446 cases. Two smaller clusters with a total of 197 and 89 cases, respectively, were seen concurrently. These clusters shared epidemiological characteristics such as age distribution, geography, and time. To investigate the possible genetic relationship between the cluster strains, these were further characterized by phage typing, pulsed-field gel electrophoresis, and Optical Mapping. Although the MLVA method proved robust and well-performing in detecting and defining clusters, the employment of a second typing method detected an additional fourth cluster among the isolates. The cluster strains were stable throughout the almost 2-year period, even though we detected changes in three of five MLVA loci in a small fraction of isolates. These changes were mainly due to the gain or loss of single repeats. Optical Mapping of the large cluster strain indicated no increased content of virulence genes; however, Optical Mapping did reveal a large insert, a probable prophage, in the main cluster. This probable prophage may give the cluster strain a competitive advantage. The molecular methods employed suggested that the four clusters represented four distinct strains, although they seemed to be epidemiologically linked and shared genotypic characteristics.
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Affiliation(s)
- Randi Føns Petersen
- Department of Microbiological Surveillance and Research, Statens Serum Institut, Copenhagen, Denmark
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