Molecular Characterization of Antimicrobial Resistance and Virulence Genotypes in Staphylococcus aureus Isolates: Investigation of mecA, pvl, and agr Groups.

BACKGROUND

This study aimed to characterize the distribution of mecA, pvl carriage, and agr groups, among clinical Staphylococcus aureus (S. aureus) isolates and to correlate these findings with comprehensive antimicrobial susceptibility profiles.

METHODS

S. aureus isolates-obtained from various clinical samples between 1 June 2025 and 30 March 2026 at a tertiary hospital in southern Turkey-were identified using the MALDI-TOF VITEK MS system. Antimicrobial susceptibility testing was performed using the VITEK 2 system in accordance with EUCAST standards. Target-specific Real-Time PCR was used for molecular detection of resistance and virulence genes (nuc, mecA, pvl, and agr loci (I-IV)).

RESULTS

Among the 100 isolates included, S. aureus identification was confirmed via real-time PCR targeting the nuc. The real-time PCR framework demonstrated a perfect correlation between mecA genotypes and phenotypic resistance profiles. The pvl significantly clustered with the agr group II; pvl-positive strains showed high resistance to erythromycin, fusidic acid, and mupirocin, while clindamycin resistance was limited to pvl-negative strains.

CONCLUSIONS

These findings characterise the local epidemiological distribution of pvl, agr groups and resistance profiles in S. aureus and confirm the independent association between pvl carriage and the MRSA phenotype. These single-centre data highlight the need for future multicentre studies incorporating sequence-based typing, whilst providing valuable information for institutional surveillance and antibiotic management.