Control of Endemic Methicillin-Resistant Staphylococcus aureus

CONTEXT: Despite the success of some countries in controlling endemic methicillin-resistant Staphylococcus aureus (MRSA), such programs have not been implemented for some hospitals with endemic infection because of concerns that these programs would be costly and of limited benefit. OBJECTIVE: To compare the costs and benefits of an MRSA control program in an endemic setting. DESIGN AND SETTING: Case-control study conducted at a medical intensive care unit (ICU) of a French university hospital with a 4% prevalence of MRSA carriage at ICU admission. PATIENTS: Twenty-seven randomly selected patients who had ICU-acquired MRSA infection between January 1993 and June 1997, matched to 27 controls hospitalized during the same period without MRSA infection. MAIN OUTCOME MEASURES: Intensive care unit costs attributable to MRSA infection, computed from excess therapeutic intensity in cases using estimates from a cost model derived in the same ICU, were compared with costs of the control program, derived from time-motion study of nurses and physicians. The threshold for MRSA carriage that would make the control strategy dominant was determined; sensitivity analyses varied rates of MRSA transmission and ratio of infection to transmission, length of ICU stay, and costs of isolation precautions. RESULTS: The mean cost attributable to MRSA infection was US 9275 (median, 5885; interquartile range, 1400-16, 720). Total costs of the control program ranged from 340 to 1480 per patient. A 14% reduction in MRSA infection rate resulted in the control program being beneficial. In sensitivity analyses, the control strategy was dominant for a prevalence of MRSA carriage on ICU admission ranging from 1% to 7%, depending on costs of control measures and MRSA transmission, for infection rates greater than 50% following transmission. CONCLUSIONS: In this example of a hospital with endemic MRSA infection, selective screening and isolation of carriers on ICU admission are beneficial compared with no isolation.