[High prevalence of methicillin-resistant Staphylococcus aureus strains in the Point G teaching hospital in Bamako, Mali].

UNLABELLED: Our aim was to study the susceptibility of Staphylococcus aureus to antimicrobial agents and to determine the methicillin-resistant S. aureus (MRSA) prevalence in the Point G teaching hospital in Bamako.

METHODS

Columbia blood agar with nalidixic acid and colistin was used for the isolation of S. aureus strains. The diffusion method was used for antimicrobial susceptibility testing.

RESULTS

Of 434 non repetitive strains of S. aureus isolated from 2007 to 2009 in the Point G teaching hospital, 297 (68.6%) were from hospital area and 137 (31.4%) were from extra-hospital area. The hospital strains were more resistant to penicillin than the extra-hospital strains (95% versus 88%; p = 0,016). Tetracycline was more active against hospital clinical isolates than extra-hospital clinical isolates (32% versus 21%; p = 0.024). Among 297 S. aureus clinical isolates, 195 (66%) were MRSA and 102 (34%) were methicillin-susceptible S. aureus (MSSA). The MRSA clinical isolates prevalence was higher in hospital area than in extra-hospital area (66% versus 55.5%; p = 0.0418). The MRSA clinical isolates prevalence was higher in the medical wards than in the surgical wards (74.8% vs 34.3%; p < 10-6). Among 251 MRSA clinical isolates, 169 (67.3%) were from urine, 39 (15.5%) from pus, 30 (12%) from blood culture, 7 (2.9%) from vagina and 6 (2.5%) from other sites. The MRSA clinical isolates prevalence was 46% in 2007, 63% in 2008 and 80% in 2009. The MRSA clinical isolates were highly more resistant to penicillin (p < 10-6), to amoxicillin combined with clavulanic acid (p < 10-6), to aminoglycosides (p < 10-6), to macrolides, lincosamides and streptogramins (p < 10-6), to norfloxacin (p < 10-6), to chloramphenicol (p < 10-6), to tetracycline (p = 0,0042), to sulfonamides (p < 10-6), to trimethoprim (p < 10-6), to fusidic acid (p < 10-6), and to fosfomycin (p = 0,0103) than the MSSA strains. The high level resistance to aminoglycosides, fluoroquinolones, macrolides, lincosamides and streptogramins was more frequent in the MRSA strains than in the MSSA strains.

CONCLUSION

The MRSA clinical isolates prevalence was very high in the Point G teaching hospital in Bamako, in the medical wards especially. The MRSA strains were drugs multiple resistant.