PREVALENCE OF INDUCIBLE CLINDAMYCIN RESISTANCE IN Staphylococcus aureus ISOLATED FROM VARIOUS CLINICAL SAMPLES AT TERTIARY CARE HOSPITAL, RAJKOT, WESTERN INDIA

Background: Multidrug resistant Staphylococcus aureus is a problem worldwide. This has led to renewed interest in usage of Macrolide-LincosamideStreptogramin B (MLSB) antibiotics to treat Staphylococcal infections. The resistance to macrolide can be mediated by msr A gene coding for efflux mechanism or via erm genes. In vitro tests for clindamycin susceptibility may fail to detect inducible clindamycin resistance thus necessitating the need to detect such resistance by a simple D test on a routine basis. Methodology: 300 S. aureus isolates were subjected to routine antibiotic susceptibility testing including cefoxitin (30ug) by modified Kirby Bauer disc diffusion method. Erythromycin Inducible resistance to clindamycin in S. aureus was tested by “D test” as per CLSI guidelines. Results: Out of the 300 isolates; MS phenotype (MS Pheno) was seen in 10.3% (31) Erythromycin Inducible Clindamycin Resistance (iMLSb) is seen in 19% (58), constitutional (cMLSb) resistance was seen in 12% (36). Out of the total 58 Erythromycin Inducible Resistance Isolates, 63.79% (37) were associated with MRSA and 36.20% (21) were associated with MSSA. Conclusion: Clindamycin is kept as a reserve drug and is usually advocated in severe MRSA infections. This study showed that D test shoul d be used mandatorily in routine disc diffusion test to detect inducible clindamycin resistance in S. aureus for optimum treatment of patients. KeywordsClindamycin resistance, Constitutive MLSB, inducible MLSB, MS MLSB, MRSA