Multidrug-Resistant Organisms: Preventing Acquisition and Transmission

Abstract

Multidrug-resistant organisms (MDRO) are a global problem, causing treatment challenges which result in worse health outcomes and high healthcare costs. As resistance to antibiotics continues to develop causing treatment failures, infection prevention strategies have become necessary. This dissertation offers research into discovering potential targets for intervention of MDRO acquisition through prevention of multiple MDRO colonization and infection and prevention of infection and transmission through the environment. The introduction for these topics will be covered in chapter one. In chapter two, we analyzed a four-year, prospective study to identify risk factors among hospitalized patients for co-colonization and coinfection (CCCI) with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE), a predecessor to vancomycin-resistant S. aureus. Using conditional logistic regression, we identified admission from another healthcare facility as a risk factor when comparing CCCI patients to patients with MRSA only and patients without MRSA or VRE, indicating healthcare exposure increases the risk of CCCI. Molecular analysis indicated CCCI may be more likely to occur in patients colonized or infected with MRSA strains typically associated with hospital-associated infections. We recognized patients who may benefit from additional resources for infection prevention and control in the hospital to prevent acquisition of an emerging MDRO through multiple organism colonization or infection. MDRO environmental contamination facilitates MDRO transmission. In chapter three, we identified a hospitalized patient type colonized with MDRO more likely to contaminate their environment. Using latent class analysis, we categorized patients into two classes based on mechanical ventilation status, consciousness status at admission and requiring assistance with activities of daily living prior to admission. Low functional status patients were more likely to contaminate their environment. Infection prevention practices, such as hygiene assistance, enhanced environmental disinfection and contact precautions may contribute to reducing the burden of environmental contamination by these patients. Chapter four includes a surveillance study of environmental contamination in a child care center with the goal of guiding environmental cleaning and disinfection practices. We demonstrated the feasibility of longitudinal surveillance of a variety of fomites to detect overall contamination and the frequency of contamination with MDRO and viral pathogens. Water-associated sites were identified as harboring a higher bioburden and being contaminated more frequently with pathogens, demonstrating the potential of water to act as a reservoir for microorganisms and distribute them in the environment. We detected a higher bioburden on objects with irregular surfaces or which were cleaned less frequently. Child care providers should consider the ability to decontaminate a surface balanced against the development of children when including items in the classroom. Chapter five examines the knowledge added from this research and the public health implications related to our findings. Support for current infection prevention and control recommendations are addressed and additional strategies for interventions are considered. Potential future research directions informed by findings in this dissertation, including investigations into mechanisms of acquisition and transmission and potential interventions to interrupt these processes are discussed. In the appendix, I present a proposal for a future research project to develop a self-screening method for VRE. While this may have multiple applications, my goal is to use this in community-based studies, where VRE is prevalent but under-investigated. Better surveillance of VRE in the community will inform best practices for prevention of transmission and acquisition in this setting, while also guiding future research regarding VRE in community.