Duration of methicillin-resistant Staphylococcus aureus colonization after diagnosis: a four-year experience from southern Sweden.

BACKGROUND The duration of colonization with methicillin-resistant Staphylococcus aureus (MRSA) is not well known and there is debate as to whether a patient colonized with MRSA ever can be defined as 'MRSA-negative'. METHODS Since 2003 all notified MRSA cases have been systematically followed in Skåne County, southern Sweden. Cultures are taken from the nares, throat, perineum and possible skin lesions. Contact tracing is conducted. The screening program continues as long as cultures are positive and then until 1 y of consecutive negative cultures for MRSA is completed. RESULTS Of the 578 MRSA cases during 2003-2006, 535 were included in this retrospective study. The median duration of colonization with MRSA was 5.9 months. Having household contacts with MRSA, young age, spa-type t002 and colonization in 2 or more locations, were significantly associated with a longer duration of colonization. Having a clinical infection treated with antibiotics (compared to clinical infection with no antibiotic treatment or asymptomatic carriage) was significantly associated with a shorter carriage time. Eradication treatment was associated with a shorter carriage time. CONCLUSION These results may have implications for the management of patients with MRSA carriage. The study indicates that MRSA carriage can be defined as 'negative' in a follow-up program and shows the importance of performing contact tracing among household members.