OCCURRENCE OF MACROLIDE-LINCOSAMIDE –STEPTOGRAMIN B RESISTANCE AMONG METHICILLIN RESISTANCE ISOLATES OF STAPHYLOCOCCI FROM CLINICAL SPECIMENSN.A. CHANDAK, B.J. WADHER AND S.R. DESHMUKH
Background : Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of infections in hospitals and community. Clindamycin resistance may be inducible or constitutive, and the rates of inducible resistance in MRSA that could produce clindamycin treatment failures vary worldwide. The streptogramins is used for patients with chronic MRSA infection, who are vancomycin-intolerant. Purpose: The present study aimed at in vitro detection of Macrolide-Lincosamide-SteptograminB resistant phenotypes of staphylococci (including methicillin resistant strains) so as to interpret the result of susceptibility tests to guide therapy. Materials and Methods: A total of 229 Staphylococci isolates from clinical isolates. Oxacillin agar screening test was used for detection of methicillin resistant in staphylococci. Antimicrobial susceptibility testing and Modified quadruple disc induction test were used for detection of drug resistance. Results: The prevalence of resistance to macrolide-lincosamide-streptograminB antibiotics showed twelve different phenotypes amongst the staphylococci isolates from clinical specimen. Within clinical isolates, 31.25% of MRSA (n=10) has inducible (iMLSB) phenotype while 6.25% in MSSA (n=4) and 8.22% in MRCoNS (n= 6). Resistance to steptograminB were also reported. Interpretation and Conclusions: This study reveals high rate of inducible clindamycin resistant in MRSA as compared to methicillin-sensitive Staphylococcus aureus (MSSA). Coagulase negative staphylococci (CoNS) showed low inducible resistance. Therefore, all erythromycin-resistant and clindamycin-sensitive should not be considered as clindamycin resistant. The value of testing these antibiotics as part of primary evaluation could be especially meaningful.
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