The Detection of Enterotoxins and Toxic Shock Syndrome Toxin Genes in Staphylococcus aureus by Polymerase Chain Reaction

Abstract

A simple polymerase chain reaction (PCR)-based procedure was developed for the detection of fragments of staphylococcal enterotoxins (SEs) SEA, SEB, SEC, SED, SEE, SEG, SEH, and SEI together with the toxic shock syndrome toxin (TSST-1) genes of Staphylococcus aureus. One hundred and twenty-nine cultures of S. aureus were selected, 39 of which were recovered from 38 suspected staphylococcal food-poisoning incidents. The method was reproducible, and 32 different toxin genotypes were recognized. The presence of SE genes was associated with S. aureus strains reacting with phages in group III, and the TSST-1 gene with phages in group I. There was a 96% agreement between the PCR results for detection of SEA-D and TSST-1 as compared with a commercial reverse passive latex agglutination assay for the detection of SEs from cultures grown in vitro. Enterotoxin gene fragments were detected in S. aureus cultures recovered from 32 of the 38 suspected staphylococcal food poisoning incidents, and of these, 17 were associated with SEE, SEG, SEH, and SEI in the absence of SEA-D. Simple PCR procedures were also developed for the detection of SE directly in spiked food samples, and this was most successfully achieved in mushroom soup and ham. Detection was less successful in three types of cheese and in cream. SEA or SEB were detected by enzyme-linked immunosorbent assay in three food samples (two of which were associated with food poisoning incidents) naturally heavily contaminated with S. aureus: the appropriate SEA or SEB gene fragments were detected directly in these three foods by PCR.

Enterotoxigenic potential of Staphylococcus aureus isolated from Artisan Minas cheese from the Serra da Canastra - MG, Brazil

“…The lack of correlation between the results from biochemical and molecular assays have already been observed in the literature (McLAUCHLIN et al, 2000;ROSEC;GIGAUD, 2002;JØRGENSEN et al, 2005). Jørgensen et al (2005) and Kérouanton et al (2007) suggested the possibility of variations in the sequences of the analyzed genes, which could hinder the proper annealing of the primers in the PCR reaction.…”

“…additional differences in the genes that would be present in the isolates. McLauchlin et al (2000) considered that the degree of homology between the enterotoxins, especially the less studied non-classical ones, could generate cross-immune reactions and generate false-positive results.…”

Establishment of Highly Specific and Quantitative Immunoassay Systems for Staphylococcal Enterotoxin A, B, and C Using Newly‐Developed Monoclonal Antibodies

“…Recently, reports have been produced for the identification of the toxin gene using PCR methods (28,41,42). However, these methods could not be applied when the bacteria have not already existed in specimens sterilized.…”

The Use of Phages and Aptamers as Alternatives to Antibodies in Medical and Food Diagnostics

“…Ingestion results in nausea, vomiting and diarrhoea while inhalation provokes non-productive cough, chest pain and dyspnea. Classical ways of detection are mainly based on multiplex PCR (McLauchlin et al 2000;Mehrotra et al 2000) and immunoassays (Freed et al 1982;Wieneke 1991), which allow quantitative or qualitative measurements in less than 24 hours. A peptide displaying-phage for the optical detection of SEB with biosensor technology was developed by Goldman et al (2000).…”