Abstract

Sumit Gupta*, Kuldeep Yadav*, Ajay Kumar Choudhary, Dr. Rajeev R. Shah, Vivek Trivedi and Apoorwa Gupta

ABSTRACT

Background and Objective: MRSA strains and their resistance are increasing worldwide. The aim of this study was to find the prevalence of MRSA strains isolated from clinical specimens and to evaluate their resistance pattern. Development of intrinsic(homogenous and heterogenous) and extrinsic (borderline) resistance in S. aureus to methicillin with decrease susceptibility to AMAs (anti microbial agents). Additionally we compared the phenotypic and genotypic methods for detection of methicillin resistance. Materials and Methods: In this cross-sectional study, a total of 500 isolates of S. aureus were collected from various clinical specimens from January 2017 to January 2018 at teaching hospital (PMCH) in Udaipur, Rajasthan region. All isolates were identified at the species level by standard biochemical tests. The methicillin resistance was evaluated using three methods: PCR for mecA gene, agar dilution for determination of oxacillin MIC and disk diffusion test to detect methicillin, oxacillin and cefoxitin resistance. Antimicrobial resistance patterns were determined by disk diffusion method according to CLSI (Clinical and Laboratory Standards Institute) guidelines. Results: The results identified 210 (42%) out of 500 isolates as MRSA. Most of the MRSA strains (65.4%), intermediate or borderline (BORSA) 06(2%) susceptible (MSSA) 284 (56%) were isolated from patients. All isolates were susceptible to vancomycin, mupirocin and linezolid. Among other antibiotics co-trimoxazole was more active against MRSA isolates. Using PCR as reference method all the phenotypic tests showed 100% specificity. 193(92%) were homogenously resistant and 17 (8%) were heterogenic resistant.