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D'Souza DH, Jaykus LA. Nucleic acid sequence based amplification for the rapid and sensitive detection of Salmonella enterica from foods. J Appl Microbiol 2004; 95:1343-50. [PMID: 14633009 DOI: 10.1046/j.1365-2672.2003.02106.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS The purpose of this study was to apply nucleic acid sequence-based amplification (NASBA) for the detection of Salmonella enterica serovar Enteritidis (S. Enteritidis) in representative foods. METHODS AND RESULTS A previously reported primer and probe set based on mRNA sequences of the dnaK gene of Salmonella were used in this study. To test for possible food matrix inhibition and assay detection limits, 25-g samples of representative food commodities (fresh meats, poultry, fish, ready-to-eat salads and bakery products) were pre-enriched with and without S. Enteritidis inoculation. The NucliSens(R) Basic Kit, supplemented with enzymes from various other commercial sources, was used for RNA isolation, NASBA amplification and electrochemiluminescent (ECL) detection. The end point detection limit of the NASBA-ECL assay was equivalent to 101 CFU of S. Enteritidis per amplification reaction. When the assay was tested on noncontaminated foods, none of the food matrices produced false-positive results. Some of the food matrices inhibited the NASBA-ECL reaction unless the associated RNA was diluted 10-fold prior to amplification. CONCLUSIONS For all food items tested, positive ECL signals were achieved after 18 h of pre-enrichment and subsequent NASBA at initial inoculum levels of 102 and 101 CFU per 25 g food sample. SIGNIFICANCE AND IMPACT OF THE STUDY This rapid, semi-automated detection method has potential for use in the food, agricultural and public health sectors.
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Affiliation(s)
- D H D'Souza
- Department of Food Science, North Carolina State University, Raleigh, NC, USA.
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FRAVALO P, HASCOËT Y, FELLIC MLE, QUEGUINER S, PETTON J, SALVAT G. CONVENIENT METHOD FOR RAPID AND QUANTITATIVE ASSESSMENT OF SALMONELLA ENTERICA CONTAMINATION: THE MINI-MSRV MPN TECHNIQUE. ACTA ACUST UNITED AC 2003. [DOI: 10.1111/j.1745-4581.2003.tb00031.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Koh CG, Tan W, Zhao MQ, Ricco AJ, Fan ZH. Integrating Polymerase Chain Reaction, Valving, and Electrophoresis in a Plastic Device for Bacterial Detection. Anal Chem 2003; 75:4591-8. [PMID: 14632069 DOI: 10.1021/ac0343836] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An integrated plastic microfluidic device was designed and fabricated for bacterial detection and identification. The device, made from poly(cyclic olefin) with integrated graphite ink electrodes and photopatterned gel domains, accomplishes DNA amplification, microfluidic valving, sample injection, on-column labeling, and separation. Polymerase chain reaction (PCR) is conducted in a channel reactor containing a volume as small as 29 nL; thermal cycling utilizes screen-printed graphite ink resistors. In situ gel polymerization was employed to form local microfluidic valves that minimize convective flow of the PCR mixture into other regions. After PCR, amplicons (products) are electrokinetically injected through the gel valve, followed by on-chip electrophoretic separation. An intercalating dye is admixed to label the amplicons; they are detected using laser-induced fluorescence. Two model bacteria, Escherichia coli O157 and Salmonella typhimurium, were chosen to demonstrate bacterial detection and identification based on amplification of several of their unique DNA sequences. The limit of detection is about six copies of target DNA.
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Affiliation(s)
- Chee G Koh
- ACLARA BioSciences, Inc., 1288 Pear Avenue, Mountain View, California 94043, USA
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Hong Y, Berrang ME, Liu T, Hofacre CL, Sanchez S, Wang L, Maurer JJ. Rapid detection of Campylobacter coli, C. jejuni, and Salmonella enterica on poultry carcasses by using PCR-enzyme-linked immunosorbent assay. Appl Environ Microbiol 2003; 69:3492-9. [PMID: 12788755 PMCID: PMC161512 DOI: 10.1128/aem.69.6.3492-3499.2003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2002] [Accepted: 03/10/2003] [Indexed: 11/20/2022] Open
Abstract
Contamination of retail poultry by Campylobacter spp. and Salmonella enterica is a significant source of human diarrheal disease. Isolation and identification of these microorganisms require a series of biochemical and serological tests. In this study, Campylobacter ceuE and Salmonella invA genes were used to design probes in PCR-enzyme-linked immunosorbent assay (ELISA), as an alternative to conventional bacteriological methodology, for the rapid detection of Campylobacter jejuni, Campylobacter coli, and S. enterica from poultry samples. With PCR-ELISA (40 cycles), the detection limits for Salmonella and Campylobacter were 2 x 10(2) and 4 x 10(1) CFU/ml, respectively. ELISA increased the sensitivity of the conventional PCR method by 100- to 1,000-fold. DNA was extracted from carcass rinses and tetrathionate enrichments and used in PCR-ELISA for the detection of Campylobacter and S. enterica, respectively. With PCR-ELISA, Salmonella was detected in 20 of 120 (17%) chicken carcass rinses examined, without the inclusion of an enrichment step. Significant correlation was observed between PCR-ELISA and cultural methods (kappa = 0.83; chi-square test, P < 0.001) with only one false negative (1.67%) and four false positives (6.67%) when PCR-ELISA was used to screen 60 tetrathionate enrichment cultures for Salmonella. With PCR-ELISA, we observed a positive correlation between the ELISA absorbance (optical density at 405 nm) and the campylobacter cell number in carcass rinse, as determined by standard culture methods. Overall, PCR-ELISA is a rapid and cost-effective approach for the detection and enumeration of Salmonella and Campylobacter bacteria on poultry.
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Affiliation(s)
- Yang Hong
- Department of Avian Medicine, College of Veterinary Medicine, The University of Georgia, Athens, Georgia 30602, USA
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Liu T, Liljebjelke K, Bartlett E, Hofacre C, Sanchez S, Maurer JJ. Application of nested polymerase chain reaction to detection of Salmonella in poultry environment. J Food Prot 2002; 65:1227-32. [PMID: 12182472 DOI: 10.4315/0362-028x-65.8.1227] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Isolation of Salmonella from environmental and processing-plant poultry samples requires the sampling of large numbers of areas within the poultry house or plant. Subsequently, the required number of samples necessitates a large volume of work for a microbiology laboratory, especially when the protocol requires the inclusion of a delayed secondary enrichment for the isolation of Salmonella. This study examined the use of the polymerase chain reaction (PCR) to identify those secondary enrichments containing Salmonella. The unique Salmonella virulence gene invA was chosen as the target for the development of a nested PCR because of its uniform distribution among Salmonella serotypes. The use of nested PCR primers increased the sensitivity of detection 100-fold, resulting in the detection of as few as four cells. There was a strong, statistically significant positive correlation between PCR and culture results as determined by chi-square (P < 0.001) and kappa (kappa = 0.915; excellent agreement) tests. Using PCR to screen primary enrichments for presumptive Salmonella contamination, we improved our efficiency at isolating Salmonella upon secondary enrichment by 20%, and no false negatives were observed. This method will not only validate the use of secondary enrichment procedures but also reduce costs and manpower required for the surveillance of Salmonella.
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Affiliation(s)
- Tongrui Liu
- Department of Avian Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602, USA
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Malorny B, Schroeter A, Bunge C, Helmuth R. Prevalence of Escherichia coli O157:H7 prophage-like sequences among German Salmonella enterica serotype Typhimurium phage types and their use in detection of phage type DT104 by the polymerase chain reaction. Vet Microbiol 2002; 87:253-65. [PMID: 12052335 DOI: 10.1016/s0378-1135(02)00064-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A 1.6kb DNA fragment identified by random amplifiable polymorphic DNA differentiation (RAPD) from a Salmonella enterica serotype Typhimurium phage type DT104 isolate was used to investigate the prevalence of the region in 160 DT104 isolates, 83 other epidemiological important S. Typhimurium phage types and 20 strains selected from 17 other Salmonella serotypes. PCR screening tests using two different primer-sets derived from the RAPD fragment's nucleotide sequence showed that 76% of the 160 DT104 isolates investigated, including subtypes DT104A, DT104B, DT104B low, DT104H and DT104L, reacted positively. High sensitivity was shown for DT104 strains expressing at least the penta-resistance pattern ACSSuT (97% of 104 strains tested). DT104 susceptible strains showed only a sensitivity of 35% (17 strains tested). In contrast, 83% of the 83 strains from the other S. Typhimurium phage types reacted negatively. Strains from five out of the 17 other serotypes showed a positive signal with one primer-set. The other primer-set exhibited only a positive reaction with one S. Dublin isolate. The analysis of a 2415bp extended sequence revealed homologies to genes encoded by Escherichia coli O157:H7 prophages, suggesting that the described region contains genes of a prophage specific for DT104 and related phage types.
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Affiliation(s)
- Burkhard Malorny
- Federal Institute for Health Protection of Consumers and Veterinary Medicine, Diedersdorfer Weg 1, Berlin, Germany
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Wang SJ, Yeh DB. 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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Affiliation(s)
- S-J Wang
- Department of Food Health, Chia Nan University of Pharmacy and Science, Tainan Hsien, Taiwan, ROC. ,tw
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Eyigor A, Carli KT, Unal CB. Implementation of real-time PCR to tetrathionate broth enrichment step of Salmonella detection in poultry. Lett Appl Microbiol 2002; 34:37-41. [PMID: 11849490 DOI: 10.1046/j.1472-765x.2002.01036.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS The present study describes the implementation of real-time PCR to tetrathionate broth enrichment step of Salmonella detection in poultry. METHODS AND RESULTS Real-time PCR with Salmonella invA-specific primers and a standard bacteriological method was applied to detect Salmonella in tetrathionate enrichment cultures of 492 intestinal homogenates and 27 drag swabs from 47 poultry flocks. The number of positive individual samples by real-time PCR and culture method was 65 (12.5%) and 35 (6.8%), respectively. The number of Salmonella-positive flocks was 13 (27.7%) by both methods. PCR detection required 25 min for up to 32 samples. Melting curve analysis revealed the Tm for Salmonella-specific PCR product as 87 +/- 1 degrees C. CONCLUSIONS Implementation of real-time PCR to tetrathionate broth enrichment step reduces the Salmonella detection time to 18 h and 25 min. Isolation of Salmonella should be carried out with PCR to determine the serovar. SIGNIFICANCE AND IMPACT OF THE STUDY Real-time PCR is a powerful tool in rapid and accurate Salmonella monitoring in poultry companies, together with standard bacteriology.
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Affiliation(s)
- A Eyigor
- Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Uludag University, Gorukle Kampusu, 16043 Bursa, Turkey
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Ji WS, Hu JL, Qiu JW, Pan BR, Peng DR, Shi BL, Zhou SJ, Wu KC, Fan DM. Relationship between genotype and phenotype of flagellin C in Salmonella. World J Gastroenterol 2001; 7:864-7. [PMID: 11854918 PMCID: PMC4695611 DOI: 10.3748/wjg.v7.i6.864] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To discover the relationship between the genotype and antigen serotype of flagellin C among Salmonella strains.
METHODS: Fragment of Salmonella flagellin C in plasmid pLS408 was cloned, sequenced and compared with the corresponding sequence in other strains. Salmonella strains including two typhi strains, one paratyphoid strain, one enteritidis and one typhimurium strain were isolated from outpatients. Genome DNA was purified respectively from these clinical isolates, then the corresponding flagellin C fragment was amplified by polymerase chain reaction, and the amplification products were analyzed by agarose gel electrophoresis.
RESULTS: The cloned fragment includes 582 nucleotides encoding the variable region and partial conservative region of Salmonella flagellin C in plasmid pLS408. With comparison to the corresponding sequences reported previously, there is only a little difference from other strains with the same flagellar serotype in both nucleotide and amino acid level. Specific PCR products were amplified in Salmonella strains with flagellar serotype H-1-d including S. muenchen, typhi and typhimurium, but not in S. paratyphoid C or S. enteritidis strains.
CONCLUSION: In this experiment, the specificity of nucleotide sequence could be found in flagellin C central variable regions as it exists in flagellar serotypes in Salmonella. It may be helpful to developing a rapid, sensitive, accurate and PCR-based method to detect Salmonella strains with serotype H-1-d.
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Affiliation(s)
- W S Ji
- Chinese PLA Institute of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, Shaanxi Province, China
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Agron PG, Walker RL, Kinde H, Sawyer SJ, Hayes DC, Wollard J, Andersen GL. Identification by subtractive hybridization of sequences specific for Salmonella enterica serovar enteritidis. Appl Environ Microbiol 2001; 67:4984-91. [PMID: 11679316 PMCID: PMC93261 DOI: 10.1128/aem.67.11.4984-4991.2001] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Salmonella enterica serovar Enteritidis, a major cause of food poisoning, can be transmitted to humans through intact chicken eggs when the contents have not been thoroughly cooked. Infection in chickens is asymptomatic; therefore, simple, sensitive, and specific detection methods are crucial for efforts to limit human exposure. Suppression subtractive hybridization was used to isolate DNA restriction fragments present in Salmonella serovar Enteritidis but absent in other bacteria found in poultry environments. Oligonucleotide primers to candidate regions were used in polymerase chain reactions to test 73 non-Enteritidis S. enterica isolates comprising 34 different serovars, including Dublin and Pullorum, two very close relatives of Enteritidis. A primer pair to one Salmonella difference fragment (termed Sdf I) clearly distinguished serovar Enteritidis from all other serovars tested, while two other primer pairs only identified a few non-Enteritidis strains. These primer pairs were also useful for the detection of a diverse collection of clinical and environmental Salmonella serovar Enteritidis isolates. In addition, five bacterial genera commonly found with Salmonella serovar Enteritidis were not detected. By treating total DNA with an exonuclease that degrades sheared chromosomal DNA but not intact circular plasmid DNA, it was shown that Sdf I is located on the chromosome. The Sdf I primers were used to screen a Salmonella serovar Enteritidis genomic library and a unique 4,060-bp region was defined. These results provide a basis for developing a rapid, sensitive, and highly specific detection system for Salmonella serovar Enteritidis and provide sequence information that may be relevant to the unique characteristics of this serovar.
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Affiliation(s)
- P G Agron
- Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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Carli KT, Unal CB, Caner V, Eyigor A. Detection of salmonellae in chicken feces by a combination of tetrathionate broth enrichment, capillary PCR, and capillary gel electrophoresis. J Clin Microbiol 2001; 39:1871-6. [PMID: 11326006 PMCID: PMC88041 DOI: 10.1128/jcm.39.5.1871-1876.2001] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This report describes a rapid detection procedure for salmonellae from chicken feces by the combination of tetrathionate primary enrichment (preenrichment [PE])-bacterial lysis-capillary PCR and capillary gel electrophoresis. Pure Salmonella enterica serovar Enteritidis 64K was reisolated and detected by capillary PCR after buffered peptone water and nutrient broth, tetrathionate broth base Hajna (TTBH), and tetrathionate broth (TTB) preenrichments. When the same culture was mixed with intestinal homogenate, bacteriological reisolation and capillary PCR detection was achieved only by TTBH and TTB preenrichments. Capillary gel electrophoresis revealed that a Salmonella genus-specific 281-bp PCR product was detected when Salmonella strains but not non-Salmonella strains were tested. The detection limit of capillary PCR with whole-cell DNA extracted from pure Salmonella enterica serovars Enteritidis 64K, Typhimurium LT2-CIP60-62, and Gallinarum 64K was 3, 3, and 9 CFU ml(-1), respectively. The detection limit of capillary PCR from whole-cell DNA extracted from intestinal homogenate artificially contaminated with the same three strains was 3, 3, and 7 CFU ml(-1), respectively. We compared the results of the capillary PCR and bacteriological examination from the natural samples. Thirty-five of 53 naturally contaminated samples produced a specific PCR product. In 9 of the 35 PCR-positive samples, Salmonella could not be detected bacteriologically either by PE or a primary and delayed secondary enrichment (DSE) combination. In the 18 PCR-negative samples, 4 samples were found to harbor Salmonella by both PE and DSE and 14 samples were positive after DSE. Fifty-three additional intestinal homogenate samples, which were negative by their PE and DSE in bacteriological examination, were found to be also negative by their PCRs. The total time required to detect Salmonella with the capillary PCR method we used was approximately 20 h. If samples are from clinically diseased birds, the total time for PCR and detection is reduced to 2 h since the 18-h PE is not required. These results indicate that TTB enrichment, bacterial lysis, and genus-specific capillary PCR combined with capillary gel electrophoresis constitute a sensitive and selective procedure which has the potential to rapidly identify Salmonella-infected flocks.
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Affiliation(s)
- K T Carli
- Department of Microbiology, Faculty of Veterinary Medicine, Uludag University, Gorukle Kampusu, 16059 Bursa, Turkey.
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Yoshimasu MA, Zawistowski J. Application of rapid dot blot immunoassay for detection of Salmonella enterica serovar enteritidis in eggs, poultry, and other foods. Appl Environ Microbiol 2001; 67:459-61. [PMID: 11133480 PMCID: PMC92600 DOI: 10.1128/aem.67.1.459-461.2001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2000] [Accepted: 10/20/2000] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica serovar Enteritidis was detected in artificially inoculated eggs within 24 h through a rapid monoclonal antibody-based dot blot immunoassay. Detection in poultry and other products required 28 h. Samples were directly enriched in homogenized egg without the need for pre- or postenrichment steps. Serovar Enteritidis was detected in the presence of other bacteria when outcompeted 1:400.
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Affiliation(s)
- M A Yoshimasu
- Department of Food Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
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