Prevalence of Clindamycin Inducible Resistance in Staphylococcus Aureus and Coagulase-Negative Staphylococci Using D-Test: A Short Report

The D-test is performed by placing clindamycin and erythromycin impregnated disks at a standard distance on the agar plate then looking for the flattening of inhibition zone around the clindamycin disk. A positive D-test indicates clindamycin inducible resistance and also predicts treatment failure possibility of this antibiotic in clinic. Prevalence of staphylococcal inducible resistance to clindamycin through the D-test was the aim of this study. In this descriptive-cross-sectional study، inducible resistance to clindamycin was examined on the 150 isolated Staphylococcus aureus (n=103) and coagulase-negative staphylococci (n=47) collected from nasal employees and clinical samples by using D-test. The statistical analysis was performed using chi-square test. Out of 103 isolated S. aureus، 22 (21. 4%) were methicillin-resistant (MRSA). Among the tested samples، 3 (2%)، 1 (0. 6%) and 2 (1. 3%) had D، D+ and HD phenotypes، respectively. Fifty-four (36%) of isolations exhibited resistance to both clindamycin and erythromycin. Prevalence of resistance to clindamycin and erythromycin between isolated MRSA and methicillin-susceptible S. aureus (MSSA) was statistically significant (p<0. 05). Phenotypical resistance to erythromycin is not always attributable to clindamycin resistance. Therefore، staphylococcus strains resistant to erythromycin and susceptible to clindamycin should be subjected to D-test assay.