High prevalence and expression of antiseptic resistance genes among infectious t۰۳۷/ST۲۳۹ methicillin-resistant Staphylococcus aureus (MRSA) strains in North Khorasan Province, Iran

Objective(s): Staphylococcus aureus is an important infectious agent and the majority of methicillin-resistant S. aureus (MRSA) infections are of nosocomial origin. To define the level and distribution of antiseptic resistance among infectious S. aureus strains we studied MRSA and methicillin-susceptible S. aureus (MSSA) isolates collected from different infection sites in an assortment of patients.Materials and Methods: S. aureus isolates were investigated for in vitro susceptibility to antiseptic agents and detection of qacA/B, smr, vanA, and mecA genes. Results: Among the S. aureus isolates we studied, ۲۵ and ۴۱ were MRSA and MSSA, respectively. The mean of minimum inhibitory concentrations (MICs) for benzethonium chloride (BTC) among MRSA was statistically significantly higher than for MSSA (۲۶ µg/ml versus ۱۱.۷ µg/ml, P=۰.۰۰۳) while there was no significant difference between MRSA and MSSA for benzalkonium chloride (BKC) and chlorhexidine digluconate (CHG). The qacA/B genes were carried in ۶۸% of the MRSA and ۵۸.۲% of MSSA (P=۰.۶۰۱), while smr was carried in ۳۹% of MRSA and ۲۹.۳% of MSSA strains (P=۱.۰۰۰). In ۱۵ out of ۲۵ cases, MRSA ST۲۳۹ with spa types t۰۳۷, t۰۳۰, and t۷۶۸۸ was isolated from the infection site with ۸۶.۶% of them carrying a resistance gene (qacA/B or qacA/B + smr). Conclusion: The frequent presence of antiseptic resistance genes and a consequently elevated MIC against antiseptics among ST۲۳۹ MRSA emphasizes the importance of mandatorily monitoring MRSA for effective infection control.

کلیدواژه ها:

Benzalkonium chloride ، Benzethonium chloride ، Chlorhexidine gluconate ، disinfection ، Methicillin-resistant - Staphylococcus aureus ، Nosocomial infection