Abstract

MOLECULAR CHARACTERIZATION OF GENTAMYCIN RESISTANT STAPHYLOCOCCUS AUREUS ISOLATES IN HOSPITAL SAMPLES

Walaa Abbas Abdulridha*

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 Gentamycin Resistant Staphylococci [GRS] which included both, Gentamycin Resistant Staphylococcus aureus [GRSA] and Gentamycin Resistant Coagulase Negative Staphylococci [GRCoNS] from different clinical samples and their invitro susceptibility pattern to various antimicrobials. Gentamycin 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 GRSA 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). Gentamycin and Amikacin showed resistance of 18.64% (11/59) each. Cefuroxime, Cefadroxil, Gentamycin 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 GRSA. Hence accurate and prompt detection of methicillin 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: Methicillin, GRSA, MRCoNS, Vancomycin.