Control of a hospital outbreak of methicillin-resistant Staphylococcus aureus infections: value of an isolation unit.

An outbreak of methicillin- and gentamicin-resistant Staphylococcus aureus infections started in a university hospital after a patient, who was not known to be colonized, was admitted. During a 3-month period 15 surgical or geriatric patients and five staff were found to be infected or colonized by the epidemic strain in five surgical/orthopaedic wards, a geriatric ward, the intensive care unit and the isolation unit. Difficulties in controlling the outbreak arose when two patients who initially had negative bacteriological screening results were returned to general wards. Both patients were subsequently shown to be colonized and caused outbreaks which led to the further closure of two general wards. There was strong circumstantial evidence to suggest that physiotherapy staff were involved with the spread of the epidemic strain. Control of the outbreak was achieved by more strict isolation of 'negative' patient contacts as well as colonized/infected patients and increasing the level of staffing on the separate isolation unit.