Resistance to desiccation and skin fatty acids in outbreak strains of methicillin-resistant Staphylococcus aureus.

Resistance to desiccation and to skin fatty acids was measured in three groups of methicillin-resistant Staphylococcus aureus (MRSA) strains and a group of control strains. Organisms from a large outbreak on a special care baby unit (SCBU), where MRSA had been isolated from staff hands but not from the environment, were significantly more sensitive to drying than strains from a burns unit where extensive environmental contamination had been demonstrated. MRSA from other wards, in the same hospital but not associated with large outbreaks, gave heterogeneous results. Fatty-acid resistance, determined by an agar dilution method, was not associated with strain origin. Some epidemic strains of MRSA were relatively sensitive to desiccation, and the abilities of such strains to spread widely on a SCBU by the hand-borne route could not be explained by enhanced resistance to skin fatty acids.