Abstract :
Introduction and Objectives: Expression of inducible clindamycin resistance (iMLSB) by
Staphylococcal isolates limits the effective use of clindamycin resulting in treatment failure. The present
study was aimed to estimate the prevalence of iMLSB.
Materials and Methods: Fifty Staphylococci isolated from various clinical specimens were identified by
standard microbiological methods and were subjected to antibiotic susceptibility testing by Kirby-Bauer
disc diffusion method and D test. Methicillin resistance was detected by cefoxitin disc diffusion method.
Results: Staphylococcus aureus constituted 62% and co-agulase negative Staphylococci 38% of total
Staphylococcal isolates. Methicillin resistance was noted in 27(54%) of isolates. Seventeen (34%) isolates
were sensitive to both erythromycin and clindamycin. Among the resistant phenotypes, constitutive
clindamycin resistance (cMLSB), Macrolide Streptogramin B resistance (MS) phenotype and iMLSB
was found in 16 (32%), 10 (20%) and in 7(14%) isolates respectively. Majority of the Staphylococcal
isolates showed resistance to penicillin (93.6%) followed by ciprofloxacin (79.6%) and erythromycin
(66%). Linezolid resistance was observed in 8% of isolates. None of the isolates were found resistant
to vancomycin.
Interpretation and Conclusion: Routine testing for iMLSB for all clinical isolates of Staphylococci
should be carried out to prevent failure of clindamycin therapy. Isolation of linezolid resistant
Staphylococci is an alarming sign and a matter of concern.
Keyword :
D test, Inducible clindamycin resistance, Methicillin resistance, Staphylococci.