ANTIMICROBIAL SUSCEPTIBILITY PATTERN OF DAPTOMYCIN-SENSITIVE MRSA (METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS) FROM SKIN AND SOFT TISSUE INFECTIONS

Abstract

Background: Staphylococcus aureus is responsible for a significant number of skin and soft tissue infections (SSTIs) mostly abscesses and infected wounds. Treatment options for Methicillin-resistant S. aureus (MRSA) are limited specifically in Pakistan either because of unavailability, toxicity or due to lack of local susceptibility data. Hence, we evaluated the antimicrobial susceptibility pattern of DAP-sensitive MRSA isolates from skin and soft tissue infections.

Material and Methods: This cross-sectional study was conducted at the Clinical Microbiology Laboratory of the Aga Khan University Hospital. One hundred and five isolates of S. aureus characterized as Daptomycin-sensitive and Methicillin-resistant were collected via consecutive sampling from pus and tissue specimens representing SSTIs from 1^st May to 31^st October 2020.  Antimicrobial susceptibility pattern of these isolates was determined using the VITEK^®2 automated system (Biomerieux Inc) on the VITEK^®2 Gram Positive Susceptibility card (AST-P580) and interpreted as sensitive, intermediate or resistant according to the Clinical and Laboratory Standards Institute’s breakpoints.

Results: Majority of the patient population was male (63%) with 85.7% isolates from cutaneous and subcutaneous abscesses and 14.3% from necrotic and non-healing wounds. All isolates were susceptible to vancomycin and linezolid, 98% to rifampicin, 81.9% to clindamycin, 76.2% to fusidic acid, 74.3% to co-trimoxazole, 66.7% to tetracycline, 58.1% to gentamicin, 24.8% to levofloxacin and 31.4% to erythromycin.

Conclusion: In view of our study findings clindamycin, co-trimoxazole and tetracycline appear to be the best possible oral or parenteral antibiotics for empirical administration in patients for less severe cases whereas, vancomycin and linezolid are drugs of choice in serious cases of MRSA SSTIs.

Keywords: Daptomycin, Methicillin-resistant Staphylococcus aureus (MRSA), Skin and soft tissue infections (SSTIs)