During an eight-month period, 25 hospitalized patients became infected orcolonized with methicillin-resistant Staphylococcus aureus(MRSA) in a 464-bed acute care, medical-surgical teaching hospital. Therewere only five cases during the eight months prior to the outbreak period (P < 0.0001). Initial measures, includingcategory-specific isolation and education, did not limit the spread of theoutbreak of a strain of MRSA. This prompted institution of additionalmeasures including (1) strict isolation of all infected and colonized cases;(2) prospective microbiological surveillance to detect additional cases; (3)multiple site cultures of identified cases to determine the extent ofcolonization; (4) employee and environment surveillance; (5) antibioticdecolonization of patients and employees; and (6) educational efforts. Thehighest number of personnel carriers were noted in one of the critical careunits where most of the cases occurred. The decolonization protocol was 100%effective for personnel carriers. The incidence of nosocomial cases of MRSAfell to zero in the five months following the implementation of thestrategy. The cost of the entire eradication process was approximately halfthat of treating a single MRSA bacteremia.