Staphylococcus aureus is well known for its pathogenicity contributed by the organism's ability to adapt to an intracellular existence. Ten Staphylococci isolates were obtained from soil, water, yogurt, and clinical samples. Biochemical assays were used to identify the isolates phenotypically, and then confirmed through 16S rRNA PCR. Moreover, resistance pattern to antibiotics were observed in Staphylococcus aureus. In silico studies were performed to understand the mechanistic properties for these triazole compounds against the identified RepA resistant protein. PCR results showed that the species identified were primarily as Staphylococcus aureus, Staphylococcus sciuri, Staphylococcus xylous and Staphylococcus cohnii. Moreover, the clinical isolate of Staphylococcus aureus was found to be resistant to methicillin and vancomycin. S. aureus have not harbored the mecA, vanA, and aroE genes, conferring resistance to these antimicrobials. Furthermore, 75% of the strains were not biofilm producers, however these isolates probed for the conserved replication initiator RepA gene, and the results indicated that the resistance to methicillin and vancomycin was plasmid-mediated. Synthesized compounds C1, C2, C3 and C4, showed antimicrobial activity against the strains. Molecular docking studies of these compounds against RepA showed the stable interactions, especially for C3. Therefore, it may be used as an effective antimicrobial against MRSA and VRSA. The present study revealed that resistance in the clinical strains of S. aureus is not encoded by mecA and vanA genes, however the association of plasmid-mediated RepA gene has been identified as the primary cause of the resistivity in these strains.

Keywords: Vancomycin Resistance Staphylococcus aureus (VRSA), Methicillin Resistance Staphylococcus aureus (MRSA), molecular mechanism, antimicrobial resistance