Inference and control of the nosocomial transmission of methicillin-resistant Staphylococcus aureus

Pei, Sen; Morone, Flaviano; Liljeros, Fredrik; Makse, Hernán; Shaman, Jeffrey L

Our findings indicate that, at its onset, during the first year of the outbreak, UK EMRSA-15 gradually invaded the hospital system from the community. Only sporadic nosocomial transmission occurred. With the accumulation of infected and colonized patients in the hospitals, a rise in nosocomial transmission occurred, reflected by an increase of the transmission rate b during the third year ( Figure 3A) . Concurrently, both the infection and colonization importation rates, I 0 and C 0 , also experienced growth. This simultaneous rise may have been caused by household transmission initiated by asymptomatically colonized patients discharged from hospitals. After this growth phase, both transmission and importation rates were suppressed. Finally, the UK EMRSA-15 outbreak appears near eliminated in Swedish hospitals, represented by the inferred low values of all parameters. However, if control measures in hospital were to be relaxed, the colonized patients might spark another outbreak due to the lengthy colonization period, which highlights the need for asymptomatic colonization control in order to effect MRSA elimination (Cooper et al., 2004a) .