Characterization of the Panton-Valentine Leucocidin-positive Methicillin-resistant Staphylococcus aureus Strains Isolated from Skin and Soft Tissue Infections at a Tertiary Care Hospital in Pakistan

Introduction: Methicillin-resistant Staphylococcus Aureus (MRSA) is globally accountable for human infections and is prevalent in the community and in hospitals, exhibiting a highly clonal population structure. This work determined the prevalence of Panton-Valentine Leucocidin gene containing MRSA (PVL+MRSA), furthermore, characterization of them through antibiotic resistance and molecular typing.Methods: MRSA strains were isolated from different specimens in the clinical laboratory of the tertiary care hospital in Pakistan. PVL+MRSA were tested against 10 antibiotics frequently applied for their management using the disc diffusion method. Afterward, molecular typing was conducted through typing of the mec gene inserted in Staphylococcal Cassette Chromosome (SCCmec) and the gene encoding Staphylococcal Protein A (spa).Results: The prevalence of PVL+MRSA was 56.4% and showed considerable resistance to antibiotics including ciprofloxacin (86.7%), erythromycin (74.6%), gentamicin (65.0%), cotrimoxazole (46.9%), clindamycin (39.7%), tetracycline (38.5%), doxycycline (37.3%), and fusidic acid (21.6%). Linezolid and quinupristin/dalfopristin showed 100% susceptibility. SCCmec typing documented the highest prevalence of SCCmec element type V (63.8%), shadowed by IV (30.1%) and III (6.0%). While spa typing deduced eight different spa types, wherein spa type t657 showed the highest prevalence (49.3%), followed by t5414 (13.2%), t008 (12.0%), and t021 (10.8%), and the remaining four spa types were sporadically present. Both typing methods revealed that the most dominant clone is the Bengal Bay clone (t657/t5414-V), followed by the USA300 clone (t008-IV), and the Southwest Pacific clone (t021-IV).Conclusion: The pandemic multidrug-resistant community-associated MRSA strains, including Bengal Bay clone and USA300 clone, are predominant in the given hospital for SSTIs.