Appearance of methicillin-resistant Staphylococcus aureus (MRSA) sensitiveto gentamicin in a hospital with a previous endemic distinct MRSA

Since 1990 a clone of gentamicin and methicillin-resistant Staphylococcus a ureus (MRSA) has remained endemic in our hospital, but since January 1996 a gentamicin-sensitive strain has progressively replaced the previous clone. We characterized the phenotypic and molecular pattern of the MRSA strains isolated in our hospital in 1996 and compared prospectively the epidemiolog ical, clinical and evolutionary characteristics of ninety patients infected or colonized by gentamicin-sensitive MRSA (GS-MRSA) (49) and by gentamicin -resistant MRSA (GR-MRSA) (41). Finally we studied the variation of aminogl ycoside consumption in our hospital from 1989 to 1996. We observed two anti biotypes (GS-MRSA and GR-MRSA) corresponding to two major chromosomal patte rns. Patients with GS-MRSA usually acquired the infection 72 hours after ho spital admission. No significant differences were observed in epidemiologic al characteristics, clinical presentation and evolution between patients wi th GS-MRSA and GR-MRSA. Since 1989 aminoglycoside intake in our hospital ha s decreased by 46%.