Date of Degree
Access restricted until 07/29/2021
PhD (Doctor of Philosophy)
Petersen, Christine A.
First Committee Member
Second Committee Member
Third Committee Member
Fourth Committee Member
Fifth Committee Member
Clostridium difficile (C. difficile) is a gram positive, anaerobic, spore forming bacterium. C. difficile infections are triggered by dysbiosis of the intestinal microbiome linked to age, immune status, and medication; particularly use of antibiotics and proton pump inhibitors (PPI). The spore forming nature of the bacteria gives it the ability to persist in the environment for long periods of time and makes it impervious to many commonly-used hospital cleaning and disinfection products. C. difficile, along with Methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin-resistant Enterococcus (VRE) are some of the leading multi-drug resistant hospital acquired infections in the United States. Environmental contamination and patient susceptibility are hypothesized as major contributors to infection transmission in a healthcare setting.
We conducted a cross-sectional pilot study aimed at determining the bioaerosol concentration of C. difficile present in the toilet plume of C. difficile infected patients’ rooms. Patient rooms within the University of Iowa Hospital and Clinics (UIHC) were sampled using a customized bioaerosol air impactor device. Environmental samples were collected before and after flushing the toilet to determine the pre-flush and post-flush levels of aerosolized bacteria. Particle density was collected during both pre and post-flush sampling. Activity levels in the rooms were recorded as a potential confounding variable. A total of 144 environmental samples were collected in 24 rooms. Clostridium difficile was detected in two of the twenty-four rooms (8%). There was a 12% (9/72) positive culture rate pre-flush compared to 23% (19/72) post-flush. Wilcoxon rank sum tests revealed a significant increase in particle concentration at the 5.0µm and 10.0µm size between rooms that produced a bacterial culture compared to rooms that did not (p-values 0.0095 and 0.0082 respectively). There was no significant association between the amount of activity in the room and detectable bioaerosol production (p-value=0.605).
Next, we performed a randomized control trial of hospital privacy curtains with antimicrobial properties to determine their ability to resist pathogenic bacterial contamination in an intensive care unit setting. Rooms within the surgical and neurological intensive care unit at UIHC were randomized to receive impregnated curtains, impregnated curtains plus Fuzion hypochlorite spray, or standard control curtains. MRSA, VRE, Pseudomonas spp. and Acinetobacter spp. were the four most frequently cultured pathogenic species. Time to event (contamination) analysis identified a significant difference in time to pathogenic contamination between the control curtains and the impregnated curtains post spray (p-value<0.001). The impregnated curtains post Fuzion spray also grew significantly less colonies of bacteria compared to the control curtains (p-value<0.001).
After evaluating environmental risk factors that contribute to Clostridium difficile infection, patient related risk factors for infection were evaluated. Proton pump inhibitors are a class of gastric acid reducers that work by reducing the amount of hydrogen ions produced in the stomach. Recent evidence suggests that prolonged use could negatively affect the intestinal microbiome making it more susceptible to enteric pathogens. A nested case control study was done to determine the association between PPI medication duration and C. difficile infection. Fecal microbiome diversity was analyzed via logistic regression in relation to the development of Clostridium difficile infection. A co-morbidity score was created to adjust for other microbiome altering conditions. PPI duration remained a significant predictor of infection after adjusting for the microbiome influence (p-value=0.0123).
Environmental contamination remains a significant risk factor for the transmission of hospital acquired infections including C. difficile. Toilets flushing has been shown to produce pathogenic bioaerosols in the healthcare setting. Hospital privacy curtains have been shown to routinely be contaminated with pathogenic bacteria including other gastrointestinal bacteria that could increase susceptibility to C. difficile infection. PPI medication, which is frequently prescribed in the hospital, has been shown to increase the risk of C. difficile infection, although specific microbiome changes could not be identified.
Clostridium difficile, Environmental contamination, Hospital acquired infections, Proton pump inhibitor
xii, 111 pages
Includes bibliographical references (pages 96-111).
Copyright © 2019 Geneva Marion Wilson
Wilson, Geneva Marion. "Environmental and pharmaceutical risk factors for the transmission of Clostridium difficile and other multi-drug resistant hospital acquired infections." PhD (Doctor of Philosophy) thesis, University of Iowa, 2019.
Available for download on Thursday, July 29, 2021