Methicillin-resistant Staphylococcus aureus outbreak in a general hospital intensive care unit.

Mantes' hospital polyvalent intensive care unit (ICU) experienced an outbreak episode caused by methicillin resistant Staphylococcus aureus (MRSA). Suspicion of physicians was strengthened by observing the weekly reading of multiresistant germs and the significative increase of MRSA carriers incidence rate, compared with the number of admission in the ICU: 5.5% to 11.3%. This outbreak was surprising: it happened immediatly after the installation in a new hospital and the reinforcement of nosocomial infection surveillance (systematic screening of every patient admitted to the I.U.C., his isolation if he presents risk factors to multiresistant germs, increasing of handwashing stations). The overlaping period of hospitalisation concerning the 13 patients being reported as SARM carrier, having the same antibiogram, and the epidemic curve suggested a cross contamination. The index case was a MRSA carrier the day of her admission and have had a recent hospitalisation in a high risk unit. MRSA has always been isolated in nasal swab. Six patients among the thirteen carriers developped an infection and have been treated by vancomycin: two systemic infections and four pulmonary infections. The mortality rate was 33% and only one of them seemed to be directly due to MRSA. Area samples were all negative. The clinical staff have been screened with nasal swab. We identified only one nasal MRSA carrier. The pulsed-field gel electrophoresis study showed that 9/11 which have been analysed were identical. This outbreak brought about staff, more sensibilisation to the nosocomial infection and updating of plain hygien rules leaded to its stop five months later.