PREVALENCE OF INDUCIBLE CLINDAMYCIN RESISTANCE AMONG STAPHYLOCOCCUS AUREUS ISOLATES FROM VARIOUS CLINICAL SAMPLES

*Dr. Syeda Fahada Zia and Dr. R. Kondal Rao

ABSTRACT

Clindamycin is an effective drug to treat methicillin resistant Staphylococcus aureus (MRSA). Since Clindamycin and Streptogramin are among the few drugs of choice in the treatment of methicillin resistant S. aureus (MRSA) infections, knowing the resistance to these antibiotics is imperative, reporting S.aureus as susceptible to Clindamycin without checking for inducible clindamycin resistance may lead to therapeutic failure. Therefore D-Test is used to screen inducible clindamycin resistance. D-test is a simple disc diffusion test giving high output results. It is used to study the Macrolide Lincosamide Streptogramin resistance (MLSB), both constitutive and inducible as well as macrolide Streptogramin resistance (MSB) in Staphylococcus aureus. The present study was aimed to find out the percentage of Staphylococcus aureus having inducible clindamycin resistance (iMLS B) in our geographic area using D-test. Also, we tried to asecertain the relationship between Methicillin-resistant Staphylococcus aureus (MRSA) and inducible clindamycin resistance. A total of 200 non-duplicate Staphylococcus aureus isolates from various clinical samples from both outpatients and in-patients were studied. Susceptibility to routine antimicrobial agents was carried our using Kirby Bauer method. Methicillin resistance was detected by oxacillin disc on Mueller Hinton agar (MHA) supplemented with 2% NaCL D- test was performed on all crythromycin-resistant and clindamycin-sensitive Staphylococcus aureus strains to detect inducible clindamycin resistance. Among 200 Staphylococcus strains, 158 were coagulase positive Staphylococcus strains and 42 were coagulase negative Staphylococcus strains. 47(23.5%) were found to be MRSA and 21 were D-test positive. Also, MRSA isolates showed both higher inducible resistance and constitutive resistance to clindamycin as compared to Methicillin- sensitive Staphylococcus aureus (MSSA). Clindamycin is kept as a reserve drug and is usually advocated in severe MRSA infections depending upon the antimicrobial susceptibility results. Therefore, clinical microbiology laboratory should report inducible clindamycin resistance routinely.

Keywords: Clindamycin, D-test, Erythromycin, Staphylococcus aureus