AbstractIntroduction: There has been renewed interest in use of Macrolide-Lincosamide-Streptogramin B (MLS
B) due to increasing resistance in methicillin resistant
Staphylococcus aureus (MRSA). Clinical failure of clindamycin therapy has been reported due to multiple mechanisms that confer resistance to MLS
B antibiotics. We report different resistant phenotypes of MLS
B in
Staphylococcus aureus (
S. aureus) and coagulase negative
Staphylococcus species (CONS).
Material and Methods: A total of 277 Staphylococcal isolates were collected from invasive clinical samples over a period of one year. Isolates were identified by standard microbiological procedures and subjected to antimicrobial susceptibility testing as per CLSI guidelines. Staphylococcal isolates were screened for methicillin resistance and Macrolide-Lincosamide-Streptogramin B (MLSB) phenotypes.
Results: Out of 277 isolates, 253 were S. aureus and 24 were CONS. Among 163(58.14%) MRSA isolates, 55(33.74%) and 34(20.86%) isolates showed inducible (iMLSB) and constitutive (cMLSB) clindamycin resistance respectively, while 19(11.11%) isolates presented with M/MSB phenotype. Inducible and constitutive clindamycin resistance was found to be greater in MRSA isolates than in methicillin sensitive Staphylococcus aureus (MSSA) (11.11% iMLSB, 13.33% cMLSB, 17.78% M/MSB).
Conclusion: Higher prevalence of iMLSB and cMLSB phenotypes specially among MRSA emphases the need of D-test to be performed while using clindamycin as an alternative to higher and parenteral antistaphylococcal antimicrobials.