High prevalence and expression of antiseptic resistance genes among infectious t037/ST239 methicillin-resistant (MRSA) strains in North Khorasan Province, Iran.

Objectives: is an important infectious agent and the majority of methicillin-resistant (MRSA) infections are of nosocomial origin. To define the level and distribution of antiseptic resistance among infectious strains we studied MRSA and methicillin-susceptible (MSSA) isolates collected from different infection sites in an assortment of patients.

Materials And Methods: isolates were investigated for susceptibility to antiseptic agents and detection of , , , and genes.

Results: Among the isolates we studied, 25 and 41 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 (26 µg/ml versus 11.7 µg/ml, =0.003) while there was no significant difference between MRSA and MSSA for benzalkonium chloride (BKC) and chlorhexidine digluconate (CHG). The genes were carried in 68% of the MRSA and 58.2% of MSSA (=0.601), while was carried in 39% of MRSA and 29.3% of MSSA strains (=1.000). In 15 out of 25 cases, MRSA ST239 with spa types t037, t030, and t7688 was isolated from the infection site with 86.6% of them carrying a resistance gene ( or + ).

Conclusion: The frequent presence of antiseptic resistance genes and a consequently elevated MIC against antiseptics among ST239 MRSA emphasizes the importance of mandatorily monitoring MRSA for effective infection control.