IN VITRO ACTIVITIES OF LINEZOLID, DAPTOMYCIN, MUPIROCIN AND TIGECYCLINE IN CLINICAL ISOLATES OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS IN SKIN AND SOFT TISSUE INFECTIONS FROM NORTH EAST INDIA

Dr. Chimanjita Phukan,* Dr Nahid Anjum and Dr. Giasuddin Ahmed

ABSTRACT

Introduction: Community-Acquired Methicillin-Resistant Staphylococcus aureus(CA-MRSA) has been recognized as an important pathogen for causing Skin and Soft Tissue Infection(SSTI). Treatments of these pathogens are a therapeutic challenge due multidrug resistance. The purpose of our study was to understand the invitro activity of the newer antimicrobials including Linezolid, daptomycin, mupirocin and tigecycline against S.aureus causing Skin and Soft tissue infections. Methodology: The staphylococcus aureus isolates from SSTIs were isolated and processed according to standard protocols. CDC definition, was used to categorized as community acquired and hospital acquired methicillin-resistant S. aureus. Isolates were subjected to antimicrobial sensitivity testing and tested for the presence of inducible clindamycin resistance. Minimum inhibitory concentration by E test was done for linezolid, daptomycin, mupirocin and tigecycline. Results: Of the 112 S.aureus isolates from SSTIs, 61.6% were methicillin resistant S. aureus (MRSA) and 38.4% were methicillin sensitive S. aureus(MSSA). Community acquired MRSA (40%) were more common among outpatients than the hospital acquired infections (29%). Children and young adults presented with most of the SSTIs. The Inducible clindamycin resistance among the S. aureus isolates were found to be 5.36% and among HA-MRSA and CA-MRSA it was 3.3% and 2.2% respectively. Linezolid resistance was 2.67% and MIC ranged 1.5 - 12μg/ml and none of the S aureus isolates were found to be resistant for daptomycin. 2.67% isolates had MICs for tigecycline greater than 1μg/ml and ranged 0.064μg/ml- ≥4 μg/ml. Mupirocin resistance was detected with a prevalence of 1.78% among the S. aureus isolates, all isolates were HA-MRSA. Conclusion: The high prevalence of CA-MRSA and the emergence of multidrug resistant strains highlights on implementation of proper infection prevention policies and antibiotic stewardship program.

Keywords: Staphylococcus aureus, Skin and Soft tissue infection, Linezolid, daptomycin, mupirocin, tigecycline.