Multiplex Reverse Transcription Polymerase Chain Reaction to Study the Expression of Virulence and Stress Response Genes in Staphylococcus aureus

Staphylococcus aureus survives well in different stress conditions. The ability of this organism to adapt to various
stresses is the result of a complex regulatory response, which is attributed to regulation of multiple genes. The aims of
the present study were (1) to develop a multiplex PCR for the detection of genes which are involved in stress adaptation
(asp23, dnaK, and groEL); alternative sigma factor (sigB) and virulence determination (entB and spa) and (2) to study the
expression of these genes during stress conditions for S. aureus culture collection strains (FRI 722 and ATCC 6538) and
S. aureus food isolates at mRNA level using multiplex reverse transcription polymerase chain reaction (RT-PCR). During
heat shock treatment groEL, dnaK, asp23, sodA, entB, spa, and sigB genes were up regulated up to 2.58, 2.07, 2.76, 2.55,
3.55, 2.71, and 2.62- folds, respectively, whereas in acid shock treatment, sodA and groEL were up regulated; dnaK was
downregulated; and entB and sigB genes were not expressed in food isolates. Multiplex PCR assay standardized in this
study offers an inexpensive alternative to uniplex PCR for detection of various virulence and stress response genes. This
study is relevant to rapid and accurate detection of potential pathogenic S. aureus in foods