Journal of Rafsanjan University of Medical Sciences

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

Gh.R. Goudarzi[1], M. Azadpour[2]

Received: 25/08/2014      Sent for Revision: 16/11/2014      Received Revised Manuscript: 21/02/2015     Accepted: 22/02/2015

Background and Objective: 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.

Materials and Methods: 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.

Results: 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).

Conclusion: 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.

Key words: Inducible resistance, Clindamycin, Staphylococcus aureus, D-test

Funding: This research was funded by Lorestan University of Medical Sciences.

Conflict of interest: None declared.

Ethical approval: The Ethics Committee of Lorestan University of Medical Sciences approved the study.

How to cite this article: Goudarzi Gh.R, Azadpour M. Prevalence of Clindamycin Inducible Resistance in Staphylococcus Aureus and Coagulase-Negative Staphylococci Using D-Test: A Short Report. J RafsanjanUniv Med Sci 2015; 14(1): 77-82. [Farsi]