ARS | Publication request: Persistence and transmission of Salmonella Infantis in a veterinary teaching hospital

Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 5, 2006
Publication Date: December 5, 2006
Citation: Dunowska, M., Morley, P.S., Traub-Dargatz, J.L., Davis, M.A., Patterson, G., Frye, J.G., Hyatt, D.R., Dargatz, D.A. 2006. Persistence and transmission of Salmonella Infantis in a veterinary teaching hospital. Research Workers in Animal Diseases Conference Proceedings. 50:138.

Technical Abstract: The purpose of this study was to compare Salmonella enterica serotype Infantis isolates obtained from patients or the environment of a veterinary teaching hospital over a period of nine years following a nosocomial outbreak to determine whether isolates were epidemiologically related or represented unrelated introductions into the hospital environment. Fifty-six S. Infantis isolates were compared based on their phenotypic (antimicrobial drug susceptibility pattern) and genotypic (pulsed-field gel electrophoresis [PFGE] pattern and presence of integrons) characteristics. Epidemiologically unrelated S. Infantis isolates clustered separately from all but two of the hospital isolates, and several isolates from different years and various sources were indistinguishable from each other in cluster analysis of two-enzyme PFGE results. A high percentage of isolates (80.3%) were resistant to at least one antimicrobial drug (AMD), with 67.8% showing resistance to >5 AMD. The majority (74.1%) of isolates tested contained type 1 integrons. Results strongly suggest that there was nosocomial transmission of Salmonella Infantis during the initial outbreak, and that contamination arising from this outbreak persisted across years despite rigorous hygiene and biosecurity precautions and may have led to subsequent nosocomial infections. Evidence of persistence and transmission of Salmonella clones across years, even in the face of rigorous preventive measures, has important implications for other facilities that have experienced outbreaks of Salmonella infections.