Environmental reservoirs of meticillin resistant Staphylococcus aureus in patients' rooms: Potential impact on care practices

To investigate the environmental contamination of rooms of patients colonised with meticillin resistant Staphylococcus aureus (MRSA), we conducted a prospective study during a five month period in a French university hospital. Environmental samples were taken once per week for each MRSA included patient, until the patient was discharged. The surfaces swabbed were the covers, the lifting pole, the bed bars, the table and the trolley. A 500-litre air sample was collected with an impactor air sampler, and a Petri dish was left open in the room for two hours. The aims of the study were to assess the impact of nasal decolonisation and dressing changes on the day of sampling on environmental contamination of the room. Thirty patients were included in this study. In total, 37.5% of the rooms tested positive: surface samples were positive in 11.8% of cases (39/320), and air samples were positive in 17.9% of cases (23/128). Much higher levels of contamination were observed on days on which dressings were changed, in the absence of nasal decolonisation with mupirocin. This study shows that the environment is often contaminated in the rooms of patients with MRSA. Our results are consistent with the findings of other studies suggesting that the environment may play an important role in the persistence of hospital epidemics, and that this contamination should be taken into account in the organisation and delivery of care and in evaluations of preventive measures.