Strategic interactions in multi-institutional epidemics of antibiotic resistance

Abstract

The increasing frequency of antibiotic resistance in hospital-acquired infections is a major public health concern that has both biological and economic causes. Here we develop conceptual mathematical models that couple the economic incentives and population biology of hospital infection control (HIC). We show that the optimal investment by a hospital for HIC changes with the proportion of patients already colonized with antibiotic-resistant bacteria (ARB) at the time of admission. As that proportion increases, the optimal behavior of a hospital is to increase spending to control ARB with low transmissibility and decrease spending on those with high transmissibility. In some cases, the global optimum investment in HIC can shift discontinuously from one that contains transmission to a do-nothing policy once the proportion already colonized at the time of admission becomes too great. We also show that investments in HIC are determined by a strategic game when several hospitals share patients. Hospitals acting selfishly and rationally will free-ride on the investments of other hospitals, and the level of free-riding should increase with the number of other hospitals in the area. Thus, in areas with many hospitals, the rational strategy for each hospital is to spend less than in areas with few hospitals. Thus, we predict that transmission rates and the prevalence of ARB should be higher in urban hospitals, for instance, compared with rural hospitals. We conclude that regional coordination and planning for HIC is an essential element of public health planning for hospital-acquired infections.game theory ͉ nosocomial infections ͉ infection control ͉ optimal control ͉ transmission dynamics

Efficient surveillance for healthcare-associated infections spreading between hospitals

“…Patient movements have also been suggested as an important factor in the spread of antimicrobial resistance between healthcare institutions (18,19). Mathematical models have confirmed the importance of patient movements in the propagation of nosocomial pathogens (20)(21)(22)(23)(24)(25).…”

Screening strategies in surveillance and control of methicillin-resistant Staphylococcus aureus (MRSA)

“…It is likely that the 'mixing' of patients and staff will have important impacts on the transmission dynamics, especially when considering multiple health-care facilities with a single community reservoir. Movements of individuals (particularly persistent carriers) between hospitals, long-term care facilities and community populations need to be included in order to model MRSA transmission dynamics effectively [31,32].…”

Patient sharing and population genetic structure of methicillin-resistant Staphylococcus aureus

“…Because MRSA can be carried asymptomatically for a long time (14), readmission could introduce a previously acquired strain into a new hospital (15). Thus, failure of one hospital's infection control could in principle affect the prevalence of MRSA in other hospitals that share patients with it (16). Previous studies have suggested that patient transfer or patient referral patterns (17) could affect the prevalence of MRSA in hospitals (1, 2, 16, 18, 19), on the basis of theoretical arguments and observations that clones of MRSA appear in neighboring hospitals.…”