NOSOCOMIAL INFECTIONS STAPHYLOCOCCUS-AUREUS IN A MEDICAL INTENSIVE-CARE UNIT (1985-1989) IN TUNIS

221 strains of Staphylococcus aureus oxacilline resistant (MetiR) caused nosocomial infections were isolated from 1985 to 1989 in a medical intensive care unit. The survey of susceptibility to antibiotics was established according to the computerized data of disk susceptibility test. The resistance phenotypes to beta-lactams, aminoglycosides and macrolides were established for epidemiological study. S. aureus infections were mainly bacteraemia (31 %) and peritonitis (12 %). These isolates were resistant to oxacillin with a high level (mean MIC 386 mug/ml). Their resistance phenotypes were MLS(Bc) (constitutive resistance to macrolides, lincosamine and streptogramines B) in 53 % and S + KGT (resistance to streptomycin, kanamycin, gentamicin and tobramycin) in 61 %. All the isolates were susceptible to pristinamycin and vancomycin (MIC 0.1 and 2 mug/ml). These phenotypes related to the spread of multiply drug resistant strains were responsible of nosocomial outbreaks. Strains with the same pattern of resistance were isolated among the medical staff and in the environment. Infection control measures allowed to stop these outbreaks.