Characterization of trap types in Staphylococcus aureus isolates from mastitis bovine and ovine milk samples in the North West of Iran

The virulence of Staphylococcus aureus is essentially determined by cell wall associated proteins and secreted toxins، whose expression is largely regulated by two-component regulatory systems (TCRSs) such as accessory gene regulator (agr) and RAP-TRAP systems. Four allelic variants of agr (agr I-IV) and trap (trap 1-4) so far have been identified. Some reports state that there are clinical trends according to each agr group، but there is a scarcity of information about trap types. So in this study، the polymorphism of the trap locus was analyzed by restriction endonuclease PCR in a population of 43 epidemiologically unrelated S. aureus isolated from bovine (n=21) and ovine (n=22) mastitis. The entire 504-bp open reading frame of the trap gene was amplified from all isolates by PCR. The PCR products were then digested with MseI، giving two different profiles corresponding to trap types 2 and 3. Isolates from cow were classified in trap types 2 (13; 61. 9%) and 3 (8; 38. 1%). The vast majority of isolates recovered from sheep belonged to trap type 2 (90. 9%) and type 3 contained only 9. 1% of the sheep isolates. In general، types 2 and 3 accounted for 76. 7% and 23. 3% of the analyzed isolates، respectively. It is worth noting that trap types 1 and 4 were not detected among the studied isolates. In conclusion some trap types were highly prevalent in mastitis cases probably because of possession of a genetic background which endows them with superior ability to infect the mammary gland.