Status of resistance to antimicrobial agents of Staphylococcus aureus strains at the laboratory of microbiology of the HU-JRA Antananarivo

Abstract

Introduction: On contact of antibiotics, S. aureus has gradually acquired multiple antibiotic resistances, including the methicillin (MRSA) and without lose its virulence. The aim of the present study was to report the evolution of resistance of S. aureus to different common antibiotics and to determine the antibiotics active against MRSA.

Materials and methods: This is a retrospective and descriptive study for 10 years from January 2005 to December 2014 at the Laboratory of Microbiology of the HU-JRA Antananarivo, the biggest academic hospital located in the capital of Madagascar. All demands for standard bacteriological examination were registered in the laboratory for various bacteriological exams or from samples taken from hospitalized patients and we included all positive cultures for S. aureus. The variables selected and used for the study were community or nosocomial sources of patients and results of susceptibility testing.

Results: A total of 906 results from 282 (31.12%) community-acquired and 624 (68.88%) nosocomial infections were studied an average of 100±25strains by year of study. Overall, the prevalence of MRSA was 13.83% (39 of 282 isolates)for community-acquired strains, and 15.70% (98 of 624) for nosocomial infections (p> 0.05)with a total of 29.53%. Resistance rate to trimethoprim-sulfamethoxazole was significantly higher in nosocomial infection than in community-acquired. No significant difference was observed in other antibiotics. Of the 137 MRSA, except vancomycin, fusidic acid is the antibiotic that worked the most in 114 cases (83.21%) followed by gentamicin in 96 cases (70.07%). Apart from ciprofloxacin and tetracycline that we have noticed an increase in resistance rates in 2012 and 2013, almost all antibiotics tested have a stable rate of resistance.

Conclusion: The antibiotics tested showed extremely high rates of resistance and that the problem of antibiotic resistance in S. aureus is effective in our center.

Keywords: Resistance -antibiotics- S. aureus - HU-JRA Antananarivo