Investigation of inducible clindamycin resistance among clinical isolates of staphylococci

The aim of this study was to investigate the inducible clindamycin resistance in 306 strains of staphylococci, isolated from various clinical samples over a period of two years. Inducible clindamycin resistance was investigated by D-test using clindamycin and erythromycin discs as per the CLSI guidelines. Out of 177 Staphylococcus aureus strains 53 (17.3%) were methicilline resistant S. aureus (MRSA) and 124 (40.5 %) were methicillin sensitive S. aureus (MSSA). Among the coagulase negative staphylococci, 121 (39.6%) were methicillin sensitive and 8 (2.6%) were methicillin resistant. Out of 306 clinical isolates 99 (36.4%) showed erythromycin resistance. Among the erythromycin resistant isolates 46 (46.5%) were CoNS of which 8 (15.1%) were MRCoNS and 38 (31.4%) MSCoNS. Out of thirty-one erythromycin resistant isolates 20 (6.5% of the total isolates) belonged to MLSBi phenotype, eleven isolates belonged to MLSBc phenotype. We conclude that it is necessary to perform D-test for detection of inducible clindamycin in staphylococci in routine antibiotic susceptibility testing.