INDUCTION OF CLINDAMYCIN RESISTANCE IN CLINICAL ISOLATES OF STAPHYLOCOCCUS AUREUS FROM A TERTIARY CARE HOSPITAL.

Abstract

Nowadays in Staphylococcus aureus isolates resistant to lincosamide, macrolide and streptogramin B (MLSB) group of antibiotics are expanded. Therefore, clindamycin is preferred drug for the treatment of infections caused by S. aureus, but due to change in sensitivity patterns of clindamycin it is leading to treatment failure. The three resistance phenotypes of MLSB antibiotics are iMLSB (inducible resistance) and cMLSB (constitutive resistance) that are resistant to macrolides, lincosamides and streptogrammins B antibiotics, whereas MS resistance that is sole resistant to macrolides and streptogramins B antibiotics. Erythromycin ribosome methylase (erm) genes are responsible for expressing inducible clindamycin resistance among S. aureus. In the present investigation, a Double disc approximation/Disc induction test (D-test) and PCR were used. Out of 428 strains the prevalence of iMLSB, cMLSB and MS phenotypes were 36 (8.41%), 47 (10.98%) and 48(11.21%) respectively. It is concluded that D-test should be routinely done to avoid treatment failure due to clindamycin resistance. In addition, PCR is a simple, quick, reliable and sensitive method that could also be used in the detection of inducible clindamycin resistance. The reason for the lower prevalence of iMLSB phenotype in the present study could be due to the reason that samples included in this study were mostly from the rural areas as the exposure of antimicrobial agents is less.

Keywords: Clindamycin resistance, D-test, ermA, ermC, iMLSB, S. aureus