An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in a dermatology day-care unit

We describe an outbreak of methicillin-resistant Staphylococcus aureus (MRS A) in a dermatology day-care unit and the methods used to determine the mec hanism of spread and control it. The epidemic strain had a characteristic s ensitivity pattern and was typeable with phages 29, 80, 95, 47, 51 and 77, which was of considerable value in interpreting the epidemiological data. T he method of spread was studied by examination of the medical and nursing r ecords of patients who had acquired MRSA (to determine which members of sta ff they had encountered and which other MRSA-positive patients had been pre sent in the department at the same time) and by the microbiological screeni ng of all patients and staff. However, screening of all staff by nasal swab bing failed to identify carriage of the epidemic strain, while extensive sw abbing of surfaces on the day-care unit also failed to show any evidence of MRSA in the environment. This suggests that the MRSA was most probably spr ead from patient to patient via the hands of staff, although there was also the possibility of direct transmission from patient to patient. Nine patie nts acquired the unique strain of MRSA and once acquired it proved difficul t to eradicate, although in the majority, the infection did not appear to b e clinically significant. However, in two patients MRSA contributed to a fa tal outcome: these were the two most elderly patients and were the only two who were receiving systemic corticosteroids. The outbreak was brought under control with rigorous hygienic measures and the decision to discharge all patients with MRSA from the day-care unit. Re peat screening (swabs of nose, axilla and groin) of all day-care unit and i n-patients 11 months after the last MRSA case showed no evidence of any res idual MRSA infection in the day-care unit.