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Liu X, Jiang Z, Liu Z, Li D, Liu Z, Dong X, Yan S, Zhu L, Cui D, Chen L, Wang J. Biofilm-forming ability of Salmonella enterica strains of different serotypes isolated from multiple sources in China. Microb Pathog 2023; 182:106275. [PMID: 37516211 DOI: 10.1016/j.micpath.2023.106275] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/22/2023] [Accepted: 07/26/2023] [Indexed: 07/31/2023]
Abstract
Salmonella is an important zoonotic and foodborne pathogen that can infect humans and animals, causing severe concerns about food safety and a heavy financial burden worldwide. The pathogen can adhere to living and abiotic surfaces by forming biofilms, which increases the risk of transmission and infection. In this study, we investigated the biofilm-forming ability of 243 Salmonella strains of 36 serotypes from different sources in China using microplate crystal violet staining method. The results showed that 99.6% tested strains, with the exception of one strain of S. Thompson, were capable of forming biofilms. The strains with the biofilm-forming ability of strong, medium and weak accounted for 2.88%, 24.28% and 72.43%, respectively. The strains of S. Havana and S. Hvittingfoss had the strongest biofilm-forming ability, with the OD570 of 0.81 ± 0.02 and 0.81 ± 0.38, respectively, while the strains of S. Agona and S. Bovismorbificans had the weakest biofilm-forming ability, with the OD570 of 0.16 ± 0.02 and 0.15 ± 0.00, respectively. Furthermore, statistical analysis results demonstrated that isolation of source had no effect on the biofilm formation ability, while the detection rates of pefABCD and ddhC were positively correlated with the biofilm formation ability of Salmonella. In particular, the detection rate of ddhC gene was more than 60% in the biofilm forming strains. These findings have important guiding significance for the investigation of pathogenesis, as well as the prevention and control of salmonellosis.
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Affiliation(s)
- Xu Liu
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Zhaoxu Jiang
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Zijun Liu
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Donghui Li
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Zhenhai Liu
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Xiaorui Dong
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Shigan Yan
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China.
| | - Liping Zhu
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China.
| | - Daoshi Cui
- Qilu Animal Health Products Co., Ltd, Jinan, 250100, China
| | - Leilei Chen
- Institute of Agro-Food Sciences and Technology, Shandong Academy of Agricultural Sciences, Jinan, 250100, China
| | - Junwei Wang
- Laboratory of Pathogenic Microorganism Inspection, China Animal Health and Epidemiology Center, Qingdao, 266032, China
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2
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Transcriptome sequencing reveals the difference in the expression of biofilm and planktonic cells between two strains of Salmonella Typhimurium. Biofilm 2022; 4:100086. [PMID: 36254114 PMCID: PMC9568869 DOI: 10.1016/j.bioflm.2022.100086] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 10/06/2022] [Accepted: 10/07/2022] [Indexed: 11/22/2022] Open
Abstract
Salmonela enterica serovar Typhimurium (S. Typhimurium) is a food-borne pathogen that can form biofilms to increase its resistance to the external environment. Through the detection of biofilm of several S. Typhimurium strains in this study, strain CDC3 with strong biofilm forming capacity and strain CVCC3384 with weak biofilm forming capacity were identified. The genes expressed in planktonic and biofilm cells of two S. Typhimurium strains were analysed by transcriptome sequencing. Results showed that the genes related to the signal transduction pathway were upregulated and genes related to motility were downregulated in strain CDC3. By comparing biofilms and planktonic cells of the two strains, we found that CDC3 regulates biofilm formation mainly through the two-component system kdpABC, while strain CVCC3384 does so mainly through motility and quorum sensing. This study revealed regulation mechanism of biofilms formation between different biofilm forming capacity strains, and provided a theoretical basis for subsequent research.
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Olson EG, Dittoe DK, Jendza JA, Stock DA, Ricke SC. Application of Microbial Analyses to Feeds and Potential Implications for Poultry Nutrition. Poult Sci 2022; 101:101789. [PMID: 35346494 PMCID: PMC9079344 DOI: 10.1016/j.psj.2022.101789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 02/05/2022] [Indexed: 11/16/2022] Open
Affiliation(s)
- Elena G Olson
- Meat Science and Animal Biologics Discovery Program, Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA
| | - Dana K Dittoe
- Meat Science and Animal Biologics Discovery Program, Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA
| | - Joshua A Jendza
- BASF Corporation, 100 Park Avenue, Florham Park, NJ 07932, USA
| | - David A Stock
- Biology Department, Stetson University, Deland, FL 32723, USA
| | - Steven C Ricke
- Meat Science and Animal Biologics Discovery Program, Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA.
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4
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Course CE, Boerlin P, Slavic D, Vaillancourt JP, Guerin MT. Factors associated with Salmonella enterica and Escherichia coli during downtime in commercial broiler chicken barns in Ontario. Poult Sci 2021; 100:101065. [PMID: 33765489 PMCID: PMC8008170 DOI: 10.1016/j.psj.2021.101065] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/29/2021] [Accepted: 02/06/2021] [Indexed: 11/22/2022] Open
Abstract
Salmonella enterica and Escherichia coli are bacteria of concern to veterinary public health and poultry health. Our research aimed to determine the factors associated with S. enterica and E. coli in commercial broiler chicken barns during the rest period between flocks to identify the best methods of sanitation for bacterial load reduction. This involved collecting samples from September 2015 to July 2016 from the floors of 36 barns before sanitation (baseline) and at 2 time intervals after sanitation, followed by microbiological and molecular analysis. A priori variables of interest included sanitation procedure (dry cleaning, wet cleaning, disinfection), sampling point (baseline, 2 d after sanitation, 6 d after sanitation), and flooring type (concrete, wood). The odds of detecting S. enterica were higher on wooden floors that were wet-cleaned than on concrete floors that were dry-cleaned, lower in the winter and spring than in the fall, and lower when samples were collected 2 d and 6 d after sanitation than at baseline. For E. coli, the concentration was higher on wooden floors than on concrete floors and in the summer than in the fall, and it was lower in postsanitation samples from disinfected barns than in presanitation samples from dry-cleaned barns and in the winter than in the fall. Among E. coli isolates, factors associated with the presence of qacEΔ1, a gene associated with resistance to quaternary ammonium compounds, included sanitation procedure, flooring type, cycle length, and the number of times per yr the barn is disinfected. Our findings highlight the importance of cleaning after litter removal, although the sanitation procedure chosen might differ depending on which pathogen is present and causing disease issues; dry cleaning appears to be preferable for S. enterica control, especially in barns with wooden floors, whereas disinfection appears to be preferable for E. coli reduction.
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Affiliation(s)
- Chelsea E Course
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
| | - Patrick Boerlin
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Durda Slavic
- Animal Health Laboratory, Laboratory Services Division, University of Guelph, Guelph, Ontario, Canada N1H 6R8
| | - Jean-Pierre Vaillancourt
- Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, Québec, Canada J2S 2M2
| | - Michele T Guerin
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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5
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Rather MA, Gupta K, Bardhan P, Borah M, Sarkar A, Eldiehy KSH, Bhuyan S, Mandal M. Microbial biofilm: A matter of grave concern for human health and food industry. J Basic Microbiol 2021; 61:380-395. [PMID: 33615511 DOI: 10.1002/jobm.202000678] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/27/2021] [Accepted: 02/06/2021] [Indexed: 12/15/2022]
Abstract
Pathogenic microorganisms have adapted different strategies during the course of time to invade host defense mechanisms and overcome the effect of potent antibiotics. The formation of biofilm on both biotic and abiotic surfaces by microorganisms is one such strategy to resist and survive even in presence of antibiotics and other adverse environmental conditions. Biofilm is a safe home of microorganisms embedded within self-produced extracellular polymeric substances comprising of polysaccharides, extracellular proteins, nucleic acid, and water. It is because of this adaptation strategy that pathogenic microorganisms are taking a heavy toll on the health and life of organisms. In this review, we discuss the colonization of pathogenic microorganisms on tissues and medically implanted devices in human beings. We also focus on food spoilage, disease outbreaks, biofilm-associated deaths, burden on economy, and other major concerns of biofilm-forming pathogenic microorganisms in food industries like dairy, poultry, ready-to-eat food, meat, and aquaculture.
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Affiliation(s)
- Muzamil A Rather
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, India
| | - Kuldeep Gupta
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, India
| | - Pritam Bardhan
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, India
| | - Munmi Borah
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, India
| | - Anupama Sarkar
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, India
| | - Khalifa S H Eldiehy
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, India.,Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Assiut, Egypt
| | - Shuvam Bhuyan
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, India
| | - Manabendra Mandal
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, India
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6
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Development and application of a visual loop-mediated isothermal amplification combined with lateral flow dipstick (LAMP-LFD) method for rapid detection of Salmonella strains in food samples. Food Control 2019. [DOI: 10.1016/j.foodcont.2019.04.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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7
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Ricke SC, Richardson K, Dittoe DK. Formaldehydes in Feed and Their Potential Interaction With the Poultry Gastrointestinal Tract Microbial Community-A Review. Front Vet Sci 2019; 6:188. [PMID: 31249838 PMCID: PMC6584747 DOI: 10.3389/fvets.2019.00188] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 05/28/2019] [Indexed: 12/27/2022] Open
Abstract
As antibiotics continue to be phased out of livestock production, alternative feed amendments have received increased interest not only from a research standpoint but for commercial application. Most of the emphasis to date has focused on food safety aspects, particularly on lowering the incidence of foodborne pathogens in livestock. Several candidates are currently either being examined or are already being implemented in commercial settings. Among these candidates are chemical compounds such as formaldehyde. Formaldehyde has historically been used to inhibit Salmonella in feeds during feed processing. Currently, there are several commercial products available for this purpose. This review will cover both the historical background, current research, and prospects for further research on the poultry gastrointestinal tract and feeds treated with formaldehyde.
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Affiliation(s)
- Steven C. Ricke
- Department of Food Science, Center of Food Safety, University of Arkansas, Fayetteville, AR, United States
| | | | - Dana K. Dittoe
- Department of Food Science, Center of Food Safety, University of Arkansas, Fayetteville, AR, United States
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8
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Çam D, Öktem HA. Optimizations needed for lateral flow assay for rapid detection of pathogenic E. coli. Turk J Biol 2017; 41:954-968. [PMID: 30814860 DOI: 10.3906/biy-1705-50] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Lateral flow assay (LFA), or the immunochromatographic strip test, is popular to use for rapid and sensitive immunoassays. Gold nanoparticles (GNPs), due to tunable optical characteristics and easy manipulation of size or shape, represent an attractive approach for LFA technology. Since most enterohemorrhagic infections result from water and food contaminations of Escherichia coli O157:H7, selective and rapid detection of this organism in environmental and biological complexes is necessary. In this study, optimized parameters of antibody (Ab)-based LFA for rapid detection of pathogenic E. coli O157:H7 are described. GNPs were used as visualizing agents. The measuring parameters include the Ab concentration on the capture lines, the concentration of gold conjugate, and flow rate. M180 and 36 nm were the ideal membrane and GNP size, respectively, for bacterial detection of LFA. The target, E. coli O157:H7, could be detected with a visual limit of detection of 105 cfu/mL in 3-5 min. Selectivity of the system was very high and the target was recognized by developed strips, regardless of its presence singly or in mixed bacterial samples.
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Affiliation(s)
- Dilek Çam
- Department of Biological Sciences, Middle East Technical University , Ankara , Turkey.,Department of Biology, Çankırı Karatekin University , Çankırı , Turkey
| | - Hüseyin Avni Öktem
- Department of Biological Sciences, Middle East Technical University , Ankara , Turkey.,Nanobiz R & D Ltd. , METU Science Park, Ankara , Turkey
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Andino A, Hanning I. Salmonella enterica: survival, colonization, and virulence differences among serovars. ScientificWorldJournal 2015; 2015:520179. [PMID: 25664339 PMCID: PMC4310208 DOI: 10.1155/2015/520179] [Citation(s) in RCA: 232] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 12/04/2014] [Accepted: 12/15/2014] [Indexed: 12/31/2022] Open
Abstract
Data indicate that prevalence of specific serovars of Salmonella enterica in human foodborne illness is not correlated with their prevalence in feed. Given that feed is a suboptimal environment for S. enterica, it appears that survival in poultry feed may be an independent factor unrelated to virulence of specific serovars of Salmonella. Additionally, S. enterica serovars appear to have different host specificity and the ability to cause disease in those hosts is also serovar dependent. These differences among the serovars may be related to gene presence or absence and expression levels of those genes. With a better understanding of serovar specificity, mitigation methods can be implemented to control Salmonella at preharvest and postharvest levels.
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Affiliation(s)
- A. Andino
- Department of Food Science and Technology, University of Tennessee, 2605 River Drive, Knoxville, TN 37996, USA
| | - I. Hanning
- Department of Food Science and Technology, University of Tennessee, 2605 River Drive, Knoxville, TN 37996, USA
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10
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Application of Molecular Approaches for Understanding Foodborne Salmonella Establishment in Poultry Production. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/813275] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Salmonellosis in the United States is one of the most costly foodborne diseases. Given that Salmonella can originate from a wide variety of environments, reduction of this organism at all stages of poultry production is critical. Salmonella species can encounter various environmental stress conditions which can dramatically influence their survival and colonization. Current knowledge of Salmonella species metabolism and physiology in relation to colonization is traditionally based on studies conducted primarily with tissue culture and animal infection models. Consequently, while there is some information about environmental signals that control Salmonella growth and colonization, much still remains unknown. Genetic tools for comprehensive functional genomic analysis of Salmonella offer new opportunities for not only achieving a better understanding of Salmonella pathogens but also designing more effective intervention strategies. Now the function(s) of each single gene in the Salmonella genome can be directly assessed and previously unknown genetic factors that are required for Salmonella growth and survival in the poultry production cycle can be elucidated. In particular, delineating the host-pathogen relationships involving Salmonella is becoming very helpful for identifying optimal targeted gene mutagenesis strategies to generate improved vaccine strains. This represents an opportunity for development of novel vaccine approaches for limiting Salmonella establishment in early phases of poultry production. In this review, an overview of Salmonella issues in poultry, a general description of functional genomic technologies, and their specific application to poultry vaccine developments are discussed.
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11
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Andino A, Pendleton S, Zhang N, Chen W, Critzer F, Hanning I. Survival of Salmonella enterica in poultry feed is strain dependent. Poult Sci 2014; 93:441-7. [PMID: 24570467 PMCID: PMC4990881 DOI: 10.3382/ps.2013-03401] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 10/15/2013] [Indexed: 12/11/2022] Open
Abstract
Feed components have low water activity, making bacterial survival difficult. The mechanisms of Salmonella survival in feed and subsequent colonization of poultry are unknown. The purpose of this research was to compare the ability of Salmonella serovars and strains to survive in broiler feed and to evaluate molecular mechanisms associated with survival and colonization by measuring the expression of genes associated with colonization (hilA, invA) and survival via fatty acid synthesis (cfa, fabA, fabB, fabD). Feed was inoculated with 1 of 15 strains of Salmonella enterica consisting of 11 serovars (Typhimurium, Enteriditis, Kentucky, Seftenburg, Heidelberg, Mbandanka, Newport, Bairely, Javiana, Montevideo, and Infantis). To inoculate feed, cultures were suspended in PBS and survival was evaluated by plating samples onto XLT4 agar plates at specific time points (0 h, 4 h, 8 h, 24 h, 4 d, and 7 d). To evaluate gene expression, RNA was extracted from the samples at the specific time points (0, 4, 8, and 24 h) and gene expression measured with real-time PCR. The largest reduction in Salmonella occurred at the first and third sampling time points (4 h and 4 d) with the average reductions being 1.9 and 1.6 log cfu per g, respectively. For the remaining time points (8 h, 24 h, and 7 d), the average reduction was less than 1 log cfu per g (0.6, 0.4, and 0.6, respectively). Most strains upregulated cfa (cyclopropane fatty acid synthesis) within 8 h, which would modify the fluidity of the cell wall to aid in survival. There was a weak negative correlation between survival and virulence gene expression indicating downregulation to focus energy on other gene expression efforts such as survival-related genes. These data indicate the ability of strains to survive over time in poultry feed was strain dependent and that upregulation of cyclopropane fatty acid synthesis and downregulation of virulence genes were associated with a response to desiccation stress.
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Affiliation(s)
- Ana Andino
- Department of Food Science and Technology, University of Tennessee, Knoxville 37996
| | - Sean Pendleton
- Department of Food Science and Technology, University of Tennessee, Knoxville 37996
| | - Nan Zhang
- Department of Food Science and Technology, University of Tennessee, Knoxville 37996
| | - Wei Chen
- Department of Food Science and Technology, University of Tennessee, Knoxville 37996
| | - Faith Critzer
- Department of Food Science and Technology, University of Tennessee, Knoxville 37996
| | - Irene Hanning
- Department of Food Science and Technology, University of Tennessee, Knoxville 37996
- Department of Genome Sciences and Technology, University of Tennessee, Knoxville 37996
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12
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Ricke SC, Khatiwara A, Kwon YM. Application of microarray analysis of foodborne Salmonella in poultry production: A review. Poult Sci 2013; 92:2243-50. [DOI: 10.3382/ps.2012-02740] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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14
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González-Gil F, Le Bolloch A, Pendleton S, Zhang N, Wallis A, Hanning I. Expression of hilA in response to mild acid stress in Salmonella enterica is serovar and strain dependent. J Food Sci 2013; 77:M292-7. [PMID: 23163946 DOI: 10.1111/j.1750-3841.2012.02684.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Salmonella enterica is the leading cause of foodborne illness with poultry and poultry products being primary sources of infection. The 2 most common S. enterica serovars associated with human infection are Typhimurium and Enteritidis. However, Kentucky and Heidelburg and the 2 most prevalent serovars isolated from poultry environments. Given the prevalence of other serovars in poultry products and environments, research is needed to understand virulence modulation in response to stress in serovars other than Typhimurium and Enteritidis. Thus, the objective of this research was to compare hilA gene expression (a master regulator of the virulence pathogenicity island) in response to acid stress among different strains and serovars of Salmonella. A total of 11 serovars consisting of 15 strains of S. enterica were utilized for these experiments. Cultures were suspended in tryptic soy broth (TSB) adjusted to pH 7.2, 6.2, or 5.5 with HCl or acetic acid. Total RNA was extracted from cultures at specific time points (0, 2, 4, and 24 h). Gene expression of hilA was measured with quantitative reverse transcriptase real time PCR (qRT-PCR). Growth and pH were measured throughout the 24 h time frame. Regulation of hilA in response to acid stress varied by serovar and strain and type of acid. The results of these experiments indicate that hilA regulation may have some impact on virulence and colonization of S. enterica. However, these results warrant further research to more fully understand the significance of hilA regulation in response to mild acid stress in S. enterica.
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Affiliation(s)
- Francisco González-Gil
- Tecnológico de Monterrey, Dept. of Food Science, Querétaro, Mexico, 64849. Author Le Bolloch is with Oniris Natl. College, Dept. of Food Science, Nantes, France, 44307
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15
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Löfström C, Hoorfar J. Validation of an open-formula, diagnostic real-time PCR method for 20-h detection of Salmonella in animal feeds. Vet Microbiol 2012; 158:431-5. [PMID: 22437008 DOI: 10.1016/j.vetmic.2012.02.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 02/14/2012] [Accepted: 02/17/2012] [Indexed: 11/17/2022]
Abstract
A comparative study of a 20-h, non-commercial, open-formula PCR method and the standard culture-based method NMKL 187, for detection of Salmonella, was performed according to the validation protocol from the Nordic organisation for validation of alternative microbiological methods (NordVal) on 81 artificially or naturally contaminated animal feed samples. The PCR method is based on culture enrichment in buffered peptone water for 16 ± 2 h followed by a magnetic beads based semi automated DNA extraction and real-time PCR analysis, including an internal amplification control. The limit of detection (LOD50) was found to be 7.19 and 7.24 CFU/sample for the PCR method and NMKL187, respectively. A very good correlation between results obtained by the two methods was found (Cohen's kappa=0.92). The relative accuracy, relative sensitivity and relative specificity were found to be 97.5%, 102.0% and 96.6%, respectively. This method is the fastest open PCR based analysis protocol for detection of Salmonella in feed samples. Implementing rapid methods such as the one validated in this study can speed up Salmonella testing of feed for food-producing animals.
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Affiliation(s)
- Charlotta Löfström
- National Food Institute, Technical University of Denmark, Mørkhøj Bygade 19, 2860 Søborg, Denmark.
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