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Dietary selenium sources alleviate immune challenge induced by Salmonella Enteritidis potentially through improving the host immune response and gut microbiota in laying hens. Front Immunol 2022; 13:928865. [PMID: 36016957 PMCID: PMC9396296 DOI: 10.3389/fimmu.2022.928865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 06/15/2022] [Indexed: 11/13/2022] Open
Abstract
The aim of this study was to evaluate the effects of different selenium (Se) sources on the immune responses and gut microbiota of laying hens challenged with Salmonella enteritidis (S. Enteritidis). A total of 240 45-week-old layers were randomly divided into eight groups with six replicates per group according to a 4 × 2 factorial design, including a blank diet without Se supplementation (CON group) and three diets with 0.3 mg/kg Se supplementation from sodium selenite (IS group), yeast Se (YS group), and selenium-enriched yeast culture (SYC group), respectively. After 8 weeks of feeding, half of them were orally challenged with 1.0 ml suspension of 109 colony-forming units per milliliter of S. Enteritidis daily for 3 days. The serum was collected on days 3, 7, and 14, and the cecum content was collected on day 14 after challenge. There was no significant difference in laying performance among the eight groups before challenge. The S. Enteritidis challenge significantly decreased the laying performance, egg quality, GSH-Px, IgG, and IgM and increased the ratio of feed and egg, malondialdehyde (MDA), Salmonella-specific antibody (SA) titers, IL-6, IL-2, IL-1β, and INF-γ. However, SYC increased the level of GSH-Px and IgG and decreased IL-6, while YS decreased the level of IL-2 and IL-1β. What is more, Se supplementation decreased the SA titers to varying degrees and reduced the inflammatory cell infiltration in the lamina propria caused by S. Enteritidis infection. In addition, the S. Enteritidis challenge disrupted the intestinal flora balance by reducing the abundance of the genera Clostridium innocuum, Lachnospiraceae, and Bifidobacterium and increasing the genera Butyricimonas and Brachyspira, while Se supplementation increased the gut microbial alpha diversity whether challenged or not. Under the S. Enteritidis challenge condition, the alteration of microbial composition by the administration of different Se sources mainly manifested as IS increased the relative abundance of the genera Lachnospiraceae and Christensenellaceae, YS increased the relative abundance of the genera Megamonas and Sphingomonas, and SYC increased the genera Fusobacterium and Lactococcus. The alteration of gut microbial composition had a close relationship with antioxidant or immune response. To summarize, different Se sources can improve the egg quality of layers challenged by S. Enteritidis that involves elevating the immunity level and regulating the intestinal microbiota.
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Isolation of infectious laryngotracheitis virus in broiler chicken in Iran: First report. VETERINARY RESEARCH FORUM : AN INTERNATIONAL QUARTERLY JOURNAL 2021; 12:259-262. [PMID: 34345396 PMCID: PMC8328262 DOI: 10.30466/vrf.2020.124157.2911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 12/07/2020] [Indexed: 11/23/2022]
Abstract
In February 2019, a severe respiratory distress with co-infection of infectious laryngotracheitis (ILT) and Newcastle disease accompanied with SalmonellaEnteritidis occurred in a broiler flock in the western region of Iran. Clinical signs included paralysis, torticollis, nasal discharge, conjunctivitis, gasping and respiratory rale with high mortality. At necropsy, caseous diphtheritic membrane adherent to the larynx and trachea was observed. Microscopically, syncytial cells formation with dense eosinophilic intranuclear inclusion bodies were main histopathological findings in tracheal tissues. Conventional polymerase chain reaction (PCR) for ICP4 gene amplification as a definitive diagnosis was utilized for the detection of ILT virus nucleic acid in suspected tracheal samples inoculated on to the chorioallantioc membrane of 11-day-old specific pathogen free (SPF) chicken eggs. Tracheal tissues taken from these SPF birds were positive by nested ILT PCR. In conclusion, because of no vaccination policy against ILT in broilers, the most probable scenario is that virus-laden dust or other fomites can be vectors and virus persistence and disease outbreak can be a sequel of wild virus introduction to the farm.
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An improved method to knock out the asd gene of Salmonella enterica serovar Pullorum. J Biomed Biotechnol 2009; 2009:646380. [PMID: 19672470 PMCID: PMC2723734 DOI: 10.1155/2009/646380] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/28/2009] [Accepted: 05/26/2009] [Indexed: 11/17/2022] Open
Abstract
An asd-deleted (Deltaasd) mutant of Salmonella enterica serovar Pullorum (SP) was constructed using an improved method of gene knockout by combining the pi-suicide plasmid system with the Red Disruption system. The asd gene was efficiently knocked out by the recombinant suicide vector, which replaced the asd gene with the CmR gene. Based on the balanced lethal host-vector system, the phenotype of the Deltaasd mutant was further defined. The improved method was simpler and more effective than previously reported conventional methods.
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Polymerase Chain Reaction Detection of Salmonella spp. in Fecal Samples of Pet Birds. Avian Dis 2008; 52:163-7. [DOI: 10.1637/8052-070507-reg] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Salmonella profile in chickens determined by real-time polymerase chain reaction and bacteriology from years 2000 to 2003 in Turkey. Avian Pathol 2005; 34:101-5. [PMID: 16191689 DOI: 10.1080/03079450500059461] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
From years 2000 to 2003, Salmonella was investigated from a total of 1785 samples comprised of chicken intestinal samples, cloacal swabs, drag swabs, litter samples and chick dust samples collected from 191 poultry breeding flocks belonging to 15 different chicken breeding stock companies in the Marmara region, Turkey by a SYBR green-based real-time polymerase chain reaction (SGBRT-PCR), by a probe-specific real-time polymerase chain reaction (PSRT-PCR) and by standardized bacteriology as described in the manual of National Poultry Improvement Plan and Auxillary Provisions, United States Department of Agriculture. Between January 2000 and July 2001, Salmonella was detected at the rates of 5.87% and 4.10% out of a total of 1242 samples by SGBRT-PCR and bacteriology, respectively. From July 2001 until December 2003, Salmonella was found at rates of 11.42% and 5.52% from a total of 543 samples by PSRT-PCR and bacteriology, respectively. The dominant Salmonella serovar was determined as Salmonella enterica subsp. enterica Serovar Enteritidis (S. Enteritidis), while serogroup C1 and C2 in 2001 and serogroup E1 in 2002 were isolated as additional serovars. As a conclusion, S. Enteritidis seems to be the major problem in poultry breeding flocks in Turkey, and both of the real-time polymerase chain reaction methods were found more sensitive than standard bacteriology for the detection of Salmonella from poultry samples.
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Abstract
Foodborne salmonellosis continues to be a public health issue of considerable concern. Animal feed has been a major link in pre-harvest food animal production. Although monitoring systems and control measures are available to limit Salmonella spp. contamination on animal feeds detection methodology is relatively time consuming in the context of time inputs for feed processing and mixing. Current cultural methods of Salmonella spp. detection in feeds require several days for confirmation. This amount of time represents significant problems if control measures are to be effectively implemented in a fashion that keeps feed processing costs low. Molecular methods offer improved sensitivity and potential reduction in assay time. In particular, several commercial polymerase chain reaction (PCR) assays, and combined PCR-hybridization assays have been suggested as possible means to implement more rapid detection of Salmonella spp. extracted from animal feeds. It has now become possible to rapidly detect and confirm the presence of foodborne Salmonella spp. in feed matrices by commercial amplification detection systems. The primary challenges remaining are to develop more reliable recovery and extraction procedures for routine processing of samples from a wide variety of feed matrices and apply molecular techniques for assessing physiological status of Salmonella spp. contaminants in animal feeds.
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Abstract
The methods commonly used for norovirus (NV) detection are based on reverse transcription-PCR (RT-PCR) followed by confirmation of the amplified sequence. To increase sensitivity, an RT-booster PCR was developed. The proposed method showed an increase in sensitivity at least 2 log units for all the NV strains tested compared with the standard RT-PCR method. Higher sensitivity was confirmed in tests on experimentally and naturally contaminated shellfish.
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Detection of Campylobacter and Escherichia coli O157:H7 from filth flies by polymerase chain reaction. MEDICAL AND VETERINARY ENTOMOLOGY 2004; 18:241-246. [PMID: 15347391 DOI: 10.1111/j.0269-283x.2004.00502.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Flies (Diptera: Muscidae) that breed in faeces and other organic refuse (filth flies) have been implicated as vectors of pathogenic bacteria including Escherichia coli O157:H7, which cause haemorrhagic colitis in humans, and Campylobacter, which is the principal causative agent of human enteritis. The potential role of filth flies in the epidemiology of these pathogens in the United States was investigated by examining the prevalence of Campylobacter spp. and E. coli O157:H7 from two Arkansas turkey facilities. Polymerase chain reaction was conducted on DNA extractions of individual Musca domestica Linnaeus, Stomoxys calcitrans (Linnaeus), Hydrotaea aenescens (Wiedemann), Adia cinerella Fallen and turkey faecal samples using primers specific for E. coli H7, O157 and Campylobacter spp. Culturing verified that the flies were carrying viable Campylobacter spp. and E. coli O157:H7. Results from this study indicated that M. domestica, S. calcitrans, H. aenescens and Anthomyids are capable of carrying Campylobacter in North American poultry facilities and that the E. coli O157:H7 is carried by house flies and black dump flies associated with poultry. This PCR method provided a rapid and effective method to identify Campylobacter spp. and E. coli O157:H7 directly from individual filth flies.
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Abstract
Contaminated poultry meat has been identified as one of the principal foodborne sources of Salmonella. The development of rapid detection assays for Salmonella would enable official agencies and food industries to identify contaminated foodstuffs in a more timely manner. In addition, these diagnostic tools could allow more 'real time' decisions to be made regarding end product acceptability. In this study, a survey was carried out to determine the prevalence of Salmonella in raw broiler carcasses. A total of 198 neck skin samples were obtained from within 40 flocks at a commercial broiler slaughtering facility. The presence of Salmonella was assessed by traditional culture methods and by a Salmonella-specific polymerase chain reaction (PCR) test. Salmonella was recovered from 32 (16%) of all samples using traditional culture methods. In contrast, the PCR assay proved to be more sensitive and detected Salmonella DNA in 38 (19%) of the samples tested. The pathogen was detected in 45 (23%) of the 198 samples when culture and PCR results were combined. The sensitivity of the PCR test was also greater than culture when detecting Salmonella from within flocks (53% of flocks by PCR, 30% of flocks by culture). The combination of both tests revealed that 55% of the flocks were contaminated with Salmonella. The PCR assay proved to be a highly specific and sensitive method for detecting Salmonella and the incorporation of a routine PCR test in conjunction with standard culture could be effective in providing a more accurate profile of the prevalence of this pathogen in broiler carcasses.
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Designing of polymerase chain reaction primers for the detection of Salmonella enteritidis in foods and faecal samples. Lett Appl Microbiol 2002; 34:422-7. [PMID: 12028423 DOI: 10.1046/j.1472-765x.2002.01114.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS In this study, novel insertion element (IE) DNA targeted polymerase chain reaction (PCR) primers were designed and further used for the specific detection of Salmonella enteritidis in foods and faecal samples. METHODS AND RESULTS Polymerase chain reaction primers, based upon their IE gene sequence (accession number Z83734), were developed for the detection of Salm. enteritidis. These primers were termed IE1L-IE1R and IE2L-IE3R. The cell lysate, rather than the extracted DNA, was used as template and preculturing of bacterial material was carried out prior to the PCR assay. The specificities of these developed primers were to be confirmed further. The PCR procedure developed was used to examine 170 endogenously contaminated samples, including poultry, seafood, meats, faecal specimens and some feed samples. Salmonella enteritidis was detected in 5.29% (nine of 170) of the samples. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY Two sets of novel PCR primers, based upon their IE gene sequence, have been developed. These primers demonstrated the ability to be used for the specific detection of Salm. enteritidis. When PCR primers IE1L-IE1R were used for the detection of artificially Salm. enteritidis-contaminated food samples, as few as 1 cell ml(-1) sample could be detected using this PCR process.
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Application of polymerase chain reaction (PCR) and TaqMan PCR techniques to the detection and identification of Rhodococcus coprophilus in faecal samples. J Microbiol Methods 2001; 47:355-68. [PMID: 11714526 DOI: 10.1016/s0167-7012(01)00343-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Rhodococcus coprophilus, a natural inhabitant of herbivore faeces, has been suggested as a good indicator of animal (as opposed to human) faecal contamination of aquatic environments. However, conventional detection methods limit its use for this as they require up to 21 days to obtain a result. In this paper an optimised method for extracting R. coprophilus DNA from faecal samples is described. PCR and 5'-nuclease (TaqMan) PCR methods were developed to allow the detection and enumeration of R. coprophilus in faecal samples within 2-3 days. Both PCR methods targeted the 16S rRNA gene, producing an amplicon of 443 bp which was specific for R. coprophilus. Sixty cells were required to produce an amplification product by conventional PCR, while as little as one cell was required for the TaqMan PCR method. The latter approach gave a linear quantitative response over at least four log units with both bacterial cells and DNA. Successful amplification by PCR was achieved using DNA extracted from cow, sheep, horse and deer faeces but was negative for samples from humans, pig, possum, duck and rabbit. These PCR methods enhance the feasibility of using R. coprophilus to distinguish faecal pollution of farmed herbivores from human pollution.
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Influence of enrichment media and application of a PCR based method to detect Salmonella in poultry industry products and clinical samples. Vet Microbiol 2001; 82:45-53. [PMID: 11423194 DOI: 10.1016/s0378-1135(01)00350-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
To attempt the rapid detection of Salmonella enterica, we have coupled a culture procedure with PCR amplification of the genus-specific invE/invA genes. The method was applied to different kinds of samples from the poultry industry and evaluated by using hydrolyzed feather meal, meat meal, litter and viscera, all experimentally inoculated with a known number of Salmonella followed by cultivation in selenite--cystine broth prior to the PCR reaction. The expected 457bp specific DNA fragment could be amplified from dilutions containing as few as 5.7CFU, indicating that the PCR technique can be successfully coupled with culture in an enrichment broth to distinguish Salmonella species from other enteric bacteria present in samples from the poultry industry. Tetrathionate broth proved to be a much better enrichment media compared to selenite-cystine when the presence of Salmonella was evaluated by PCR in 1-day-old chicks experimentally infected with known numbers of Salmonella. Samples included cecal tonsils and viscera, collected at 48h and 7 days postinfection. The PCR technique was more sensitive in detecting infected animals than the standard microbiological procedure, which detected only 47% of all PCR positive samples.
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Efficacy of a commercial polymerase chain reaction-based assay for detection of Salmonella spp. in animal feeds. J Appl Microbiol 2000; 89:710-8. [PMID: 11054177 DOI: 10.1046/j.1365-2672.2000.01171.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Salmonellosis is a cyclic problem in the food industry, to which animal feed has been contributory. Current conventional methods of Salmonella spp. detection require 96 h for detection and confirmation. With modern and just-in-time production schedules, a 96-h hold represents a significant expense in storage and decontamination. The commercially available assay, 'BAX for Screening/Salmonella' (BAX), is based on the principle of the polymerase chain reaction and may represent a significant decrease in assay time. Seven fresh feed formulations, two fresh feed ingredients, seven stored feeds and two stored feed ingredients were artificially contaminated with a primary poultry isolate of Salmonella typhimurium and analysed by conventional and BAX methodology. The results of BAX agreed with conventional plating results for 16 of 18 samples spiked with 1200 cfu 10 g(-1) of feed and 13 of 18 samples spiked with 40 cfu 10 g(-1) of feed. Indigenous Salmonella spp. were detected in five of eight samples of poultry diets by conventional methods. With BAX, Salmonella spp. could not be detected in any of the samples after only 7 h of enrichment but could be detected in two dietary samples after 13 h of enrichment and four dietary samples after 24 h of enrichment. Specific sequences of salmonella DNA that were extracted from poultry diets could be detected with BAX.
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Detection of low numbers of Salmonella in environmental water, sewage and food samples by a nested polymerase chain reaction assay. J Appl Microbiol 1999; 87:418-28. [PMID: 10540245 DOI: 10.1046/j.1365-2672.1999.00835.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A polymerase chain reaction (PCR) assay with two nested pairs of primers selected from conserved sequences within a 2.3 kb randomly cloned DNA fragment from the Salmonella typhimurium chromosome was developed. The nested PCR assay correctly identified 128 of a total of 129 Salmonella strains belonging to subspecies I, II, IIIb and IV. One strain of Salm. arizona (ssp. IIIa) tested negative. No PCR products were obtained from any of the 31 non-Salmonella strains examined. The sensitivity of the assay was 2 cfu, as determined by analysis of proteinase K-treated boiled lysates of Salm. typhimurium. The performance of the assay was evaluated for environmental water, sewage and food samples spiked with Salm. typhimurium. Water and sewage samples were filtered and filters were enriched overnight in a non-selective medium. Prior to PCR, the broth cultures were subjected to a rapid and simple preparation procedure consisting of centrifugation, proteinase K treatment and boiling. This assay enabled detection of 10 cfu 100 ml(-1) water with background levels of up to 8700 heterotrophic organisms ml(-1) and 10000 cfu of coliform organisms 100 ml(-1) water. Spiked food samples were analysed with and without overnight enrichment in a non-selective medium using the same assay as above. Nested PCR performed on enriched broths enabled detection of <10 cfu g(-1) food. Variable results were obtained for food samples examined without prior enrichment and most results were negative. This rapid and simple assay provides a sensitive and specific means of screening drinking water or environmental water samples, as well as food samples, for the presence of Salmonella spp.
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APPLICATION OF GENE AMPLIFICATION IN CONJUNCTION WITH A HYBRIDIZATION SENSOR FOR RAPID DETECTION OF SALMONELLA SPP. AND FECAL CONTAMINATION INDICATORS IN ANIMAL FEEDS. ACTA ACUST UNITED AC 1998. [DOI: 10.1111/j.1745-4581.1998.tb00202.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
The polymerase chain reaction (PCR) is a nucleic acid-based technique that enables the rapid and sensitive detection of specific micro-organisms. Although this technique is widely used in veterinary research, it has not yet found applications in routine microbiological analysis of veterinary clinical samples. However, advances in sample preparation together with the increasing availability of specific gene sequences will probably lead to the more widespread diagnostic use of PCR in the future. PCR is likely to have a strong impact in the epidemiology, treatment and prevention of animal infectious diseases.
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PCR amplification of the fimA gene sequence of Salmonella typhimurium, a specific method for detection of Salmonella spp. Appl Environ Microbiol 1996; 62:4303-8. [PMID: 8953701 PMCID: PMC168256 DOI: 10.1128/aem.62.12.4303-4308.1996] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The goal of this study was to evaluate the suitability of the fimA gene amplification by PCR as a specific method for detection of Salmonella strains. Salmonella typhimurium and other pathogenic members of the family Enterobacteriaceae produce morphologically and antigenically related, thin, aggregative, type 1 fimbriae. A single gene, fimA, encodes the major fimbrial unit. In order to obtain higher specificity, we have selected a series of primers internal to the fimA gene sequence and have developed a PCR method for detecting Salmonella strains. A collection of 376 strains of Salmonella comprising over 80 serovars, isolated from animals and humans in Canada, have been used to evaluate this PCR method. Forty non-Salmonella strains were also tested by the same procedure. Cultures were screened by inoculating a single colony of bacteria directly into a PCR mixture containing a pair of primers specific for the fimA gene. The specific PCR product is an 85-bp fragment which was visualized by polyacrylamide gel electrophoresis and ethidium bromide staining. All Salmonella strains gave positive results by the PCR. Feed and milk samples contaminated by Salmonella strains were also detected by this procedure. The detection of all Salmonella strains tested and the failure to amplify the fragment from non-Salmonella strains confirm that the fimA gene contains sequences unique to Salmonella strains and demonstrate that this gene is a suitable PCR target for detection of Salmonella strains in food samples.
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Abstract
A polymerase chain reaction (PCR) for the specific detection of the gene sequence, sefA, encoded by all isolates of Salmonella enteritidis, was developed. The PCR could detect as few as four S enteritidis washed bacterial cells but egg contents inhibited the PCR. Eggs spiked with 50 S enteritidis bacterial cells were homogenised, inoculated into buffered peptone water and grown at 37 degrees C for 16 hours, when the PCR was successful. A positive internal control was developed to differentiate between true and false negative PCR results for the detection of S enteritidis. In a limited trial of the egg handling procedures and the PCR, one of 250 chickens' eggs from retail outlets was found to be contaminated with S enteritidis.
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Strategies to accelerate the applicability of gene amplification protocols for pathogen detection in meat and meat products. Crit Rev Microbiol 1995; 21:239-61. [PMID: 8688154 DOI: 10.3109/10408419509113542] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Traditionally, microbiological testing of meat products has involved isolating microorganisms and performing specific biochemical, and in some cases serological, tests to confirm the presence or absence of suspected food-borne pathogens. Given the public attention meat products have received as sources of food-borne disease, there has been considerable interest in the application of rapid detection techniques that require hours rather than days for completion. Theoretically, rapid detection methods could reduce the time from the initial sampling to confirmation so that conclusive results would be available by the time to process the meat product. Both direct gene probe hybridization as well as gene amplification methods show promise as rapid detection techniques. At present, direct gene probe hybridization are being commercially utilized to confirm the presence of a suspected pathogen. A number of gene amplification protocols for detecting food-borne bacterial pathogens have been published. However, many of these studies have utilized spiked samples rather than naturally contaminated samples and many of them have involved extended template extraction/purification methodologies. There is still only a very limited amount of information on the efficacies of the various protocols in detecting bacterial pathogens, especially toxigenic Escherichia coli, Salmonella spp., Campylobacter spp., and Listeria spp., in naturally contaminated food samples. In order to develop gene amplification protocols that have relevance to the meat industry, there must be a concerted effort to utilize naturally contaminated samples in the development and evaluation of protocols, as well as to initiate multilaboratory round robin evaluations of select protocols. Availability of multilaboratory tested methodologies would provide a means to design pathogen detection strategies at the quality control level rather than an end product confirmatory response to an already documented outbreak.
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Abstract
An overview of the principles of the polymerase chain reaction, ligase chain reaction, self-sustained sequence replication and Q beta replicase is given. The application of these methods for the diagnosis of veterinary infectious and hereditary diseases as well as for other diagnostic purposes is discussed and comprehensive tables of reported assays are provided. Specific areas where these DNA-based amplification methods provide substantial advantages over traditional approaches are also highlighted. With regard to PCR-based assays for the detection of viral pathogens, this article is an update of a previous review by Belák and Ballagi-Pordány (1993).
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Comparison of the polymerase chain reaction using genus-specific oligonucleotide primers and microbiologic culture for the detection of Salmonella in drag-swabs from poultry houses. Poult Sci 1994; 73:1276-81. [PMID: 7971671 DOI: 10.3382/ps.0731276] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Drag-swab samples were collected from 18 poultry houses at 9 broiler farms. Fifty drag-swab samples were tested for Salmonella by microbiologic culture using selective enrichment and the polymerase chain reaction (PCR) with oligonucleotide primers specific for all members of the genus Salmonella. Drag-swab samples were tested for Salmonella using PCR before and after enrichment. Only one sample was positive by PCR prior to enrichment. Forty-seven of the drag-swabs samples tested after enrichment were positive for Salmonella using PCR, and 29 were positive by microbiologic culture. All but one of the culture-positive samples were positive by PCR; this discordant sample was classified as indeterminate by PCR. Salmonella was identified in houses from all nine farms by PCR and eight of nine farms by microbiologic culture. Salmonella was found in all 18 houses by PCR and in 15 of 18 houses by microbiologic culture. In this study, PCR was significantly (P < .001) more sensitive than culture for environmental monitoring of Salmonella using drag-swabs.
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