Inducible clindamycin resistance among gram positive cocci in a tertiary care centre

Resistance in gram positive bacteria not only increases morbidity and mortality, but also the costs of management of hospitalized patients. The determination of antimicrobial susceptibility of a clinical isolates is often crucial for the optimal antimicrobial therapy of the infected patients. There have been reports indicating increase in the ratio of Staphylococci resistance to Macrolide-Lincosamide-Streptogramin B (MLS_B) group and failure in the treatment with clindamycin infection with microorganisms with inducible resistance to MLS_B group. The present study was undertaken considering the paucity data on inducible MLS_B from a tertiary care centre in Haldwani, (Nainital). A total of 182 gram positive cocci obtained from consecutive clinical specimens were included, consisting of 19.7% methicillin resistant Staphylococcus aureus (MRSA), 41.7% methicillin sensitive S. aureus (MSSA), 8.7% methicillin-resistant coagulase-negative staphylococci (MRCNS), 17.5% methicillin-sensitive coagulase-negative staphylococci (MSCNS) isolates and 12% Streptococcus spp. Of the 182 isolates, 61 (33.5%) had ER-R (erythromycin resistant) and CL-S (clindamycin sensitive) phenotype. Among 61 ER-R and CL-S isolates, 30 (49%) were recorded as inducible clindamycin resistance. Since the rate of inducible clindamycin is high (49% in our study), accurate reporting of inducible MLS_B would allow the clinician to retain confident in clindamycin.