Methicillin-resistantStaphylococcus aureusin hospitals and the community: Stealth dynamics and control catastrophes

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) represents a serious threat to the health of hospitalized patients. Attempts to reduce the spread of MRSA have largely depended on hospital hygiene and patient isolation. These measures have met with mixed success: although some countries have almost eliminated MRSA or remained largely free of the organism, others have seen substantial increases despite rigorous control policies. We use a mathematical model to show how these increases can be explained by considering both hospital and community reservoirs of MRSA colonization. We show how the timing of the intervention, the level of resource provision, and chance combine to determine whether control measures succeed or fail. We find that even control measures able to repeatedly prevent sustained outbreaks in the short-term can result in long-term control failure resulting from gradual increases in the community reservoir. If resources do not scale with MRSA prevalence, isolation policies can fail ''catastrophically.''

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

“…For models explicitly including the community, there are two components to R 0 : a withinhospital value (r 0 ) and a term to include the possibility of multiple returns to hospital [19]. The withinhospital reproduction number in the absence of intervention, given by…”

“…Whereas stochastic models define movements of individuals to be chance events occurring at random time-intervals determined by the model parameters, meaning the outcome may be different for different simulation runs. There have been a number of previous models looking specifically at nosocomial infection transmission dynamics [10][11][12][13][14][15][16][17][18][19]. This work builds on those studies, particularly those by Cooper et al [4,18,19] which use stochastic models to explore the spread of nosocomial pathogens.…”

“…There have been a number of previous models looking specifically at nosocomial infection transmission dynamics [10][11][12][13][14][15][16][17][18][19]. This work builds on those studies, particularly those by Cooper et al [4,18,19] which use stochastic models to explore the spread of nosocomial pathogens. The novel aspect of this work, however, is that we model transmission between a hospital and community and within this setting include both control (by isolation) as well as active surveillance, in a single framework.…”

“…The framework is based closely on Cooper et al [4,19]. Briefly, we model a closed population consisting of both a fixed-size hospital and the community it serves.…”

Clinical significance of methicillin-resistantStaphylococcus aureuscolonization in residents in community long-term-care facilities in Spain

“…Several studies have highlighted the relevance of this epidemiological aspect which might influence the infection control practices implemented by acutecare hospitals [18][19][20][21][22] but there are limited data on the relationship of MRSA colonization and the development of infection in residents of LTCFs [12,14]. This aspect has usually been assessed in settings where patients are at great risk of MRSA infection, such as intensive care units [10].…”