Comparison between the Vitek Immunodiagnostic Assay System and PCR for the detection of pathogenic microorganisms in...

The comparison between the Vitek Immunodiagnostic Assay System (VIDAS) and PCR methods for the detection of the pathogenic microorganisms Salmonella Typhimurium, Listeria monocytogenes, Escherichia coli O157:H7, Clostridium perfringens, and Staphylococcus aureus in salchich6n (a type of Spanish fermented dry sausage) was studied. The automated mini-VIDAS method and the PCR method were used to detect the presence of these microorganisms in 90 samples grouped into six batches (one control batch, and five batches inoculated with Salmonella Typhimurium, L. monocytogenes, E. coli O157:H7, S. aureus, and C. perfringens, respectively). The determinations were carried out on fresh sausage, semicured (14 days), and finished product (28 days of curing). The concordance between both methods was 100%. For salchichón-type sausage samples, both the VIDAS method and PCR (in comparison to traditional methods) permit a significant reduction in the time required for the detection of the pathogens assayed. The absence of Salmonella Typhimurium, E. coli O157:H7, L. monocytogenes, S. aureus, their enterotoxins, and C. perfringens were verified in the control batch. Conversely, for batches inoculated with these pathogens, the results were positive in the fresh sausage up to 14 days of curing and in the finished product; this demonstrated the null or scant influence of the curing conditions and the constitutive lactic acid biota on the pathogens investigated.