Abstract

MOLECULAR CHARACTERIZATION OF RIFAMPICIN RESISTANT STAPHYLOCOCCUS AUREUS ISOLATES IN HOSPITAL SAMPLES

Raheleh Monajjemi*

ABSTRACT

Rising level of resistance to a wide range of antibiotics by both Staphylococcus aureus [SA] and Coagulase Negative Staphylococci [CoNS] represent a significant threat to future treatment efficacy. Present study was carried out to determine the prevalence of Rifampicin Resistant Staphylococci [GRS] which included both, Rifampicin Resistant Staphylococcus aureus [RRSA] and Rifampicin Resistant Coagulase Negative Staphylococci [GRCoNS] from different clinical samples and their invitro susceptibility pattern to various antimicrobials. Rifampicin resistance was tested by oxacillin and cefoxitin disk diffusion method. The antibiotic susceptibility pattern of all the isolates was determined by modified Kirby bauer disc diffusion method. Minimum Inhibitory Concentration MIC of Vancomycin was determined by E-test method. Of the 186 isolates, 129 isolates (69.35%) were identified as SA and the remaining 57 (30.64%) as GRCoNs. The frequency of RRSA was 34.10% (44/129) and GRCoNS was 26.31% (15/57). All MRS isolates were 100% resistant to penicillin and recorded 100% sensitivity to vancomycin. The % resistance of GR isolates towards Teicoplanin was 1.69% (1/59) and Linezolid was 6.77% (4/59). Rifampicin and Amikacin showed resistance of 18.64% (11/59) each. Cefuroxime, Cefadroxil, Rifampicin and Erythromycin showed higher resistance of 74.57%, 64.40%, 64.40% and 61.01% respectively. A higher rate of antibiotic resistance was noted in GRCoNS as compared to RRSA. Hence accurate and prompt detection of Rifampicin resistance are of key importance in ensuring proper antibiotic treatment in infected patients and control their spread in the hospital environment. A detailed knowledge of their sensitivity to antibacterial agents is thus necessary to facilitate the development of effective strategies to combat the growing problem of resistance.

Keywords: Rifampicin, RRSA, MRCoNS, Vancomycin.