Presence of Staphylococcus aureus and staphylococcal enterotoxin A Production and Inactivation in Brazilian Cheese Bread

Abstract

Ingesting food contaminated by pathogens and/or their toxins can cause foodborne illness. In this sense, this study investigated the occurrence of enterotoxigenic S. aureus in frozen cheese bread dough and assessed the production and thermosensitivity of SEA in artificially contaminated cheese dough. E. coli counts were determined by MPN. Confirmation of the presence of S. aureus was carried out by biochemical and molecular identification. The detection of the genes sea, seb, sec, and sed was performed using the PCR. The detection of SEA in artificially contaminated cheese dough, before and after baking at 180 ºC for 35 minutes was performed using the RPLA. All samples contaminated with E. coli had NMP < 5.0×10 2 CFU / g. None of the isolated S. aureus strains expressed the classical enterotoxin genes sea, seb, sec, and sed. However, as there are 23 serologically distinct staphylococcal enterotoxins, we cannot rule out the HIGHLIGHTS• The study shows the S. aureus counts of the 100 frozen cheese bread samples analyzed.• 27 samples (27.0%) had S. aureus counts greater than 5.0 × 10 3 CFU/g.• None of the 62 S. aureus strains isolated carried the genes sea, seb, sec, or sed.• Heat treatment at 180 °C for 35 minutes was not sufficient to inactivate SEA.