Abstract
Antimicrobial-resistant bacteria cause big problems in health care. Infections with these bacteria are hard to treat and lead to high morbidity, mortality, and costs. In this PhD thesis, carriage and transmission dynamics of multidrug-resistant Enterobacteriaceae have been investigated in various settings. Mathematical models were used to derive estimates for these
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epidemiological traits. Mathematical modeling can support in the decision making and provide guidance to policymakers on how to most efficiently use resources and set infection control measures, such as antibiotic use, hand hygiene, cleaning, and cohorting.
Duration of carriage has been studied in various bacteria, resistance mechanisms, and settings. We have looked at duration of carriage with multidrug-resistant Enterobacteriaceae after intensive care unit (ICU) discharge in European ICUs (median duration 1.5 months), Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae during and between admissions to long-term acute care hospitals (LTACHs) in Chicago, USA (median duration 165 and 270 days, respectively), OXA-48 producing Enterobacteriaceae during an outbreak in the Netherlands (median duration 278 days for K. pneumoniae and 225 days for Escherichia coli), ESBL-producing bacteria in Dutch households (median duration 267 days for persons with a previous ESBL-infection and 111 days for their household members), and ESBL-producing E. coli during an outbreak in a nursing home in the Netherlands (13 months for E. coli ST131 and 2 to 3 months for E. coli non-ST131). Duration of carriage was found to be influenced by the type of bacteria and the resistance mechanism, antibiotic use, if there was an infection, and the setting in which patients were studied.
We have studied transmission of KPC-producing Enterobacteriaceae in LTACHs in Chicago, USA, and transmission of OXA-48 producing Enterobacteriaceae during an outbreak in a Dutch hospital. We also investigated transmission of ESBL-producing Enterobacteriaceae in households in the Netherlands and during an outbreak in a nursing home in the Netherlands. Transmission capacity of multidrug-resistant Enterobacteriaceae varied for different bacteria, resistance mechanisms, settings, and the implementation of infection prevention measures.
Furthermore, we have looked at the presumed hyperendemicity of E. coli ST131 and K. pneumoniae ST258 versus other E. coli and K. pneumoniae clones, respectively. If these clones are truly hyperendemic, interventions may be targeted to these specific clones. In one of our studies we found a longer duration of carriage with E. coli ST131 compared to other E. coli clones, but no difference was found in the transmission capacity. In a literature review with meta-analysis we could not confirm hyperendemicity of E. coli ST131 or K. pneumoniae ST258.
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