Study of Community and Hospital Associated Methicillin Resistant Staphylococcus Aureus With Special Reference to Inducible Clindamycin Resistance in a Tertiary Care Hospital

Abstract

MRSA has been considered a major nosocomial pathogen in healthcare facilities but recently it has been observed emerging in the community as well. Clindamycin is a preferred therapeutic option in the treatment of both methicillin susceptible and resistant staphylococcal infections. The present study was aimed to determine the incidence of constitutive and inducible clindamycin resistance among Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and Hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) isolates. A 600 staphylococcal strains were isolated from various clinical specimens. Antibiotic susceptibility tests were performed using standard method. Methicillin resistance was detected by cefoxitin (30 ug) disc diffusion test using Mueller-Hinton Agar. D-test was performed on all erythromycin resistant and clindamycin sensitive isolates to detect inducible clindamycin resistance. MRSA was documented in 28 % amongst 600 isolates of S. aureus. Out of these 64.66 % and 35.33 % isolates of S. aureus were hospital associated and community associated respectively. Among these, 216 S. aureus were resistant to Erythromycin, 61 isolates were MRSA. Out of these 42 (68.85 %) were HA-MRSA and 19 (31.14) were CA-MRSA. We observed 3 (15.78 %), 16 (84.21 %), 0 % were iMLSB, MS phenotype and cMLSB in CA-MRSA respectively. 18 (42.85 %) iMLSB, 21 (50 %) MS phenotype and 3 (7.14 %) cMLSB observed in HA-MRSA. Our study suggested that MLSB resistance in S. aureus should be under constant surveillance in every country and region. The D-test for detection of iMLSB resistance should be carried out routinely in laboratories so as to prevent therapeutic failures.