Ventilation grilles as a potential source of methicillin-resistant Staphylococcus aureus causing an outbreak in an orthopaedic ward at a district general hospital.

An investigation of the source of an MRSA outbreak at a UK hospital found that the cause was an intermittently operated ventilation system. Ventilation grilles were found to be contaminated with EMRSA-15. It was found that daily system shutdown was causing a temporary negative pressure which drew air in from the ward and likely contaminated the outlet grilles. The index for the outbreak was a patient moved into the hospital from another large hospital. States that it is likely that contaminated air was blown back from the grilles at switch-on. After thorough cleaning of the system and reintroduction of a continuous running cycle, the outbreak ceased. The was no further infection six months following the cleaning operation.