Determination of antimicrobial susceptibility patterns and inducible clindamycin resistance in Staphylococcus aureus strains recovered from southeastern Turkey

Abstract

In this study, we determined the susceptibility patterns of Staphylococcus aureus strains to various antimicrobials and prevalence of inducible clindamycin resistance (ICR) in these isolates. Two hundred and one S aureus strains, isolated from various clinical samples, were included in the study. Antibiotic susceptibilities were studied by disc diffusion method on the basis of the guidelines by the Clinical and Laboratory Standards Institute. The disc diffusion induction test (D test) was applied to determine ICR resistance among erythromycin-resistant S aureus isolates. Of the 201 S aureus strains, 101 (50.2%) were resistant to methicillin. All strains were susceptible to vancomycin, teicoplanin, quinupristin/dalfopristin, and linezolid. It was found that 54 (53.4%) methicillin-resistant S aureus (MRSA) strains were erythromycin resistant, and 40 (39.6%) of them showed constitutive clindamycin resistance. ICR was detected in seven (6.9%) MRSA strains. It was found that 13 (13.0%) methicillin-susceptible S aureus (MSSA) strains were erythromycin resistant. Constitutive clindamycin resistance was seen in one (1.0%) MSSA strain, and ICR was detected in 10 (10.0%) cases. There was a high rate of methicillin resistance among S aureus strains in our hospital. However, no statistically significant difference of ICR was observed between MRSA and MSSA strains (p=0.434) or between inpatients and outpatients (p=0.804). It was concluded that ICR should be routinely evaluated in each S aureus case to avoid therapy failure among patients.