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

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

Observed incidence over a 6-year outbreak period is reported in Figure 1A . The relative date of diagnosis and associated ward of each observed infection were recorded; however, information on type of ward was not provided. Previous studies indicate that heterogeneity in infection risk exists across different types of ward (Bootsma et al., 2006) . For instance, patients in intensive care units (ICUs) typically suffer a higher risk of infection than those in non-ICU settings due to higher patienthealthcare-worker contact rates, high levels of antibiotic use, and high patient vulnerability to infection. In this study dataset, however, we observed no clear clustering of infections in certain wards. In Figure 1B , we use a raster plot to display the distribution of infections in 114 infected wards over time. Infections are distributed without noticeable clustering, presumably due to effective control measures taken in the study hospitals that maintain a low infection rate even in ICU settings (Tiemersma et al., 2004) .