Molecular detection and characterization of methicillin-resistant Staphylococcus pseudintermedius (MRSP) ST2361 in a healthcare setting.

BACKGROUND

Staphylococcus pseudintermedius, a commensal in dogs, is an emerging zoonotic pathogen with increasing methicillin-resistant (MRSP) strains. This study investigated MRSP isolates from hospital environments and healthcare workers in Bojnurd, Iran, to assess antimicrobial resistance and zoonotic potential.

METHODS

Nasal swabs from healthcare workers (n = 40) and hospital supplies (n = 35) were cultured. Phenotypic and genotypic analyses included antimicrobial susceptibility testing (Kirby-Bauer), PCR for resistance (mecA, vanA, cfr) and virulence genes (pvl, hla, icaA/D), SCCmec typing, and multilocus sequence typing (MLST).

RESULTS

Two MRSP isolates (ST2361) were identified, one from a nasal swab and another from hospital supplies. Both exhibited resistance to β-lactams (cefoxitin, penicillin), fluoroquinolones, macrolides, and sulfonamide-trimethoprim, but susceptibility to tetracyclines, gentamicin, linezolid, and vancomycin. PCR confirmed mecA and virulence genes (pvl, hla, icaA/D). A SCCmec pattern consistent with type IV and identical ST2361 profiles suggested potential clonal relatedness.

CONCLUSION

The presence of MRSP ST2361 in humans and hospital environments highlights its zoonotic and nosocomial transmission risks. The isolates' multidrug resistance and virulence genes underscore the need for improved diagnostics, antimicrobial stewardship, and infection control measures in healthcare settings.