Detection of inducible clindamycin resistance in staphylococcus aureus and CONS at tertiary care hospital

Abstract

Background: The increasing prevalence of Methicillin resistant among staphylococci (MRSA) is an increasing problem. Increasing incidence of infections due to MRSA has led to emphasis on the need for safe & effective agents to treat both systemic & localized Staphylococcal infections. Clindamycin has been used to treat pneumonia & soft tissue and musculoskeletal infections due to MRSA. One important issue in Clindamycin treatment is the risk of clinical failure during therapy caused by MLSB inducible resistance. Objectives: To isolate and identify Staphylococcus aureus and CONS from all clinical samples & to determine the inducible Clindamycin resistance among the Staphylococcus aureus and CONS. Methods: A total of 100 isolates of Staphylococcus aureus and CONS from various samples were isolated. Methicillin resistance was detected by using a 1 μg Oxacillin disc. The D-test was performed using the discs of Clindamycin (CL)(2μg) and Erythromycin (ER)(15μg) placed at a distance of 15mm (centre to centre) along with routine antibiotic susceptibility testing. Results: Among Staphylococcus aureus, MSSA isolates were 32(47.05%) compared to MRSA isolates, 26(38.24%) and among CNS, MSCONS isolates were 8(11.77%) compared to MRCONS 2(2.9%).A total of 12(17.64 %) isolates showed iMLSB, of which 8(11.77%) were MRSA, 2(2.9%) were MSSA and 2(2.9%) MRCONS isolates. Conclusion: Prevalence of inducible Clindamycin resistance among Staphylococcal isolates was significant. Hence the implementation of this D-test routinely, which is simple, reliable & inexpensive will reveals the iMLSB & cMLSB phenotype & prevents the therapeutic failure of Clindamycin. Keywords: Methicillin resistant Staphylococcus aureus (MRSA), Inducible Clindamycin resistance, D-test, Erythromycin, iMLSB phenotype