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Estimation of the Diagnostic Accuracy of the invA ‐gene‐based PCR Technique and a Bacteriological Culture for the Detection of Salmonella spp. in Caecal Content from Slaughtered Pigs using Bayesian Analysis
Author(s) -
MainarJaime R. C.,
Atashparvar N.,
ChirinoTrejo M.
Publication year - 2008
Publication title -
zoonoses and public health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.87
H-Index - 65
eISSN - 1863-2378
pISSN - 1863-1959
DOI - 10.1111/j.1863-2378.2007.01096.x
Subject(s) - salmonella , biology , rappaport , serotype , brilliant green , tetrathionate , bacteriology , microbiology and biotechnology , microbiological culture , polymerase chain reaction , feces , shigella , veterinary medicine , food science , bacteria , gene , chemistry , medicine , philosophy , genetics , biochemistry , theology , organic chemistry
Summary The goal of this study was to estimate the accuracy of the invA ‐gene‐based polymerase chain reaction (PCR) and a culture technique based on pre‐enrichment with buffered peptone water, three selective enrichment media (selenite, tetrathionate and Rappaport‐Vassiliadis broths) and four selective, solid media (Xylose‐Lysine‐Tergitol‐4, Salmonella / Shigella , Hekton‐Enteric and MacConkey), for the detection of Salmonella organisms from caecal samples from slaughter pigs. For this purpose a latent‐class (Bayesian) approach was used. Two hundred and three slaughtered pigs were used after grouping them into two groups of 96 and 107 animals. Sensitivity (Se) was estimated to be 56% (95% probability interval 40, 76) for culture and 91% (81, 97) for PCR. The specificity (Sp) of the PCR was 88% (80, 95) while the Sp of the culture had been considered 100% in the statistical analysis as all culture‐positive samples were confirmed by serotyping. PCR Se was not affected by the Salmonella serotypes present in the samples analysed. Accordingly, a minimum of 25.5% of the pigs was estimated to harbour Salmonella organisms in their faeces. It was concluded that bacteriology on caecal samples alone was a poor diagnostic method, and that the PCR method could be considered a cost‐effective alternative to culture in Salmonella monitoring programmes. However, given the moderate Sp of this molecular technique, PCR‐positive samples should be further confirmed through bacteriology.