The usefulness of masks in preventing transient carriage of epidemic methicillin-resistant Staphylococcus aureus by healthcare workers.

We assessed the usefulness of wearing masks in preventing epidemic methicillin-resistant Staphylococcus aureus (EMRSA) carriage in nursing and physiotherapy staff on two dedicated EMRSA units. In the first phase of the study, members of staff were screened for EMRSA carriage immediately before and after periods of duty using nose, throat and hand swabs. During the second phase of the study, masks were worn by staff carrying out procedures associated with significant EMRSA exposure and examined for EMRSA as described for the first phase. Both phases were conducted over a period of two months. Forty-eight percent of nursing staff were colonized with EMRSA at some time during the first phase of the study. Wearing masks significantly reduced nasal, throat and hand carriage of EMRSA (P= 0.05). We conclude that the wearing of masks by healthcare workers performing certain activities for EMRSA positive patients may prevent transient colonization and hence may be a useful intervention in the control of EMRSA in the hospital environment. Copyright 2001 The Hospital Infection Society.