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

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

Cost-effective interventions can be practiced by the targeted screen and decolonization of identified high-risk patients. In order to evaluate the effectiveness of such interventions, we performed a retrospective control experiment. Specifically, we used the inferred parameters in Figure 3A to run the model for 6 years to reproduce the outbreak. Every 4 weeks, we used currently available information (as would be available in real time) to estimate patient colonization probabilities (see details in Materials and methods). The colonization probabilities estimated in real time are highly correlated with the results obtained using information from the whole course of the epidemic, shown in Figure 4C . During the model integration, every 4 weeks, we selected patients with an estimated colonization probability higher than a certain threshold for screening. If positive, these inpatients were decolonized. To assess the impact of decolonization success rate on intervention impact, two efficiencies, 100% and 75%, were tested, and we repeated the experiment 1000 times. The findings show that the proposed intervention strategy can avert considerable numbers of colonization and infection ( Figure 5A-B) . Decreasing the decolonization threshold leads to a larger screened population (as shown in the inset of Figure 5B ), and thus reduces colonization and infection further. However, the marginal benefit becomes negligible below a certain threshold value, as the remaining colonized and infected patients are possibly caused by importation, which cannot be directly controlled by inpatient intervention. The decolonization success rate also plays an important role, as indicated by the increased colonization and infection for the lower success rate.