Distinctive antimicrobial resistance phenotypes of PVL-positive Staphylococcus aureus in a Vietnamese tertiary hospital

Objective: To explore the Panton-Valentine leukocidin (PVL) carriage and antimicrobial resistance phenotypes of community-associated methicillin-resistant Staphylococcus (S.) aureus in Vietnam. Methods: S. aureus isolates were collected at the University Medical Center, Ho Chi Minh City. Antimicrobial susceptibility testing was performed according to CLSI M100-S35 and PVL genes ( lukS/F-PV ) were detected using multiplex real-time PCR. Results: We collected a total of 102 clinical S. aureus isolates between January and June 2025. PVL was detected in 40.2% (41/102) of isolates, and all PVL-positive isolates were identified as methicillin-resistant S. aureus , indicating a strong association between PVL carriage and methicillin resistance. PVL-positive isolates showed significantly higher resistance to erythromycin (92.7% vs . 70.5%; P =0.006) and markedly lower resistance to gentamicin (12.2% vs . 68.9%; P <0.001), thereby defining a distinctive antimicrobial resistance phenotype. No significant differences were observed for other antimicrobial agents, and vancomycin susceptibility remained preserved in both groups. Conclusions: PVL-positive S. aureus isolates display a characteristic erythromycin-resistant and gentamicin-susceptible phenotype, likely reflecting specific underlying genetic backgrounds rather than direct PVL effects. Further molecular epidemiological studies are needed to elucidate the genetic relationships and lineage distribution of these isolates in Vietnam.