The involvement of companion animals in transmission of resistance within animal and human populations is widely accepted, yet poorly understood. Indicators or risk factors associated with companion animals being hosts or vehicles of transmission have not been fully explored within the context of an animal's interaction with other animals or humans. The objective of this dissertation was to characterize the relationship between companion animals, humans, and environmental surfaces within a veterinary teaching hospital (VTH), as it relates to prevalence, acquisition, persistence, and transmission of resistant bacteria.Between 2007 and 2009 three distinct groups were enrolled or sampled for this study: (1) animals admitted to the emergency and critical care (ECC), orthopedics (Ortho), soft tissue (ST), and internal medicine (IM) wards; (2) veterinary students going through their clinical rotations and faculty and staff working in the aforementioned wards; and (3) environmental surfaces within the ECC, Ortho, ST, IM wards, and surgery office, prep and recovery areas, and surgical suites. Rectal and nasal samples were collected from animals at admission and discharge; fecal and nasal samples were collected from students at the beginning and end of their clinical rotations; and environmental samples, as well as, fecal and nasal samples were collected from faculty and staff at the beginning of every 4th rotation. All samples were processed for isolation and identification of enterococci, staphylococci, and Escherichia coli. Antimicrobial susceptibility testing was performed and additional molecular tests (pulsed-field gel electrophoresis and multilocus sequence typing) were performed on a selection of isolates. Additionally, epidemiological data were collected by abstraction of animals' charts and questionnaires completed by students, faculty and staff.These data were analyzed first within each group (animals, humans, and environmental samples) and then globally, with all groups combined. Certain objects within the VTH were identified as more likely to carry organisms. Additionally, factors that increase the risk of an animal either acquiring Methicillin-resistant Staphylococcus aureus or having persistence of multi-drug resistant E. coli were identified. Clinical procedures performed by students and faculty and staff that would increase the risk of carriage of resistant bacteria were also identified. From these results, molecularly identical isolates were isolated from different environmental sites, different animals, different faculty or staff members, animals and faculty or staff, and students and the environment. By using date of sample collection inferences into route of transmission can be made, however, due to longer time gaps between samples, firm conclusions on direction of transmission cannot be reported. However, these data are applicable to issues of infection control guidelines within VTHs. The VTH patients were not the only possible source for the resistant organisms isolated during this study, which implies that students, faculty and staff share this responsibility. Additionally, special attention should be paid to areas of the VTH that are not a focus of routine cleaning, such as the scale; and specific consideration should be given to patients who visit multiple areas of a VTH during their admission.
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