Prevalence of Mupirocin Resistance in Staphylococci Isolated from Skin and Soft Tissue Infections

Introduction: Mupirocin (pseudomonic acid A) is a topical antimicrobial agent with excellent antistaphylococcal activity. It inhibits protein synthesis by binding specifically to iso-leucyl-tRNAsynthetase enzyme. It is used to treat superficial skin infections and to control spread of Methicillin Resistant Staphylococcus aureus (MRSA), which is now endemic in India. The increased pressure of MRSA infections among patients and its carriage in health care staff has led to the indiscriminate use of mupirocin which has resulted in emergence of its resistance. Mupirocin susceptibility is categorized into two types: low level mupirocin resistance with MIC of ? 4 ?g/ml, and high level mupirocin resistance with MIC ? 200 ?g/ml. Aim: The present study is aimed to determine prevalence of mupirocin resistance, the rates of high and low level mupirocin resistance and the antimicrobial susceptibility patterns of Staphylococcus aureus and Coagulase negative Staphylococcus (CONS) species isolated from skin and soft tissue infections. Materials and methods: Clinical isolates of Staphylococcus aureus and CONS, isolated from skin and soft tissue infections from patients of inpatient and outpatient departments were included in the study and identified as Staphylococcus aureus and CONS by standard laboratory techniques. The antibiotic susceptibility testing was done by CLSI guidelines. Methicillin resistance was detected by using cefoxitin discs (30?g) along with routine sensitivity testing. Zone of inhibition ? 22mm was reported as Methicillin sensitive Staphylococcus, whereas ?21mm was reported as Methicillin resistant Staphylococcus. Low and High level mupirocin resistance was screened by using 5?gm and 200?gm discs respectively. Results: Out of total 68 samples collected 49 (72.1%) were sensitive and 19 (27.9%) were resistant 5?gm mupirocin disc and 52 (76.5%) were sensitive and 16 (23.5%) were resistant to 200?gm mupirocin disc.