Detection of the enterotoxin-producing genes in staphylococcus aureus isolated from bovine mastitis milk by PCR in Tabriz and Urmia regions

Recently molecular methods، such as PCR have been used successfully for the identification of different genes in microoganisms. The aim of this study was to detect the enterotoxin-producing genes in Staphylococcus aureus as major human pathogens in cattle milk samples by PCR. Milk samples were collected from individual cattle in industrial dairy herds of Tabriz (5 herds) and Urmia (4 herds). In order to isolation of S. aureus by cultural methods، bacteriological examinations were done on all samples. Yellow colored colonies which were mannitol positive on mannitol salt agar، suspected as S. aureus. Biochemical tests were used for the presumptive identification of all suspected isolates. Based on the presence of aroA gene which encodes the enzyme 5-enolpyruvylshikmate-3-phosphate synthase (EPSPS)، 50 S. aureus were confirmed. S. aureus ATCC 29213 used as positive control. DNA extracted from all isolates and the PCR carried out using specific primers for S. aureus enterotoxins (A-H). Among the total of 50 S. aureus isolates، 5 were positive for sec (3 from Urmia and 2 from Tabriz)، 6 were positive for seg (2 from Urmia and 4 from Tabriz) and one isolate from Urmia was positive for seh gene. The genes for sea، seb، sed، and see were not detected in any of isolates. The results of this study revealed that enterotoxin-producing genes are present in the milk samples of different regions. In order to have more information about the distributions of the enterotoxin-producing genes in S. aureus، more investigations should be done on more samples from Urmia and Tabriz and also other regions of Iran.