PCR (nuc gene) Based Identification of Antibiotic Resistant Staphylococcus aureus Isolated from Mastitis

Abstract

Milk sample from cattle showing clinical signs of mastitis were collected and subjected to cultural characterization and biochemical analysis to identify the etiology. Gram staining of the isolated organism was identified as Staphylococcus spp by biochemical tests. The isolate was confirmed as Staphylococcus aureus in Mannitol salt agar which produced yellow colored colonies and assessed for its susceptibility to antibiotics by disc diffusion method of antibiotic sensitivity test. The isolate showed sensitivity to Enroflxacin, Tetracycline and resistance to Amoxicillin, Ceftriaxone, Penicillin G, Cotrimoxazole and Streptomycin.  The resistant isolates were screened for the presence of nuc gene in Staphylococcus aureus for methicillin resistance by polymerase chain reaction. The polymerase chain reaction amplified 270bp amplicon indicating the presence of nuc gene in Staphylococcus aureus isolated from the milk sample. The presence of methicillin resistant Staphylococcus aureus in the milk sample emphasizes the occurrence and role of milk in the transfer of antimicrobial resistance between animals and human beings.