Outbreak of Salmonellosis Caused by Salmonella enterica Serovar Newport MDR‐AmpC in a Large Animal Veterinary Teaching Hospital

Background: Nosocomial salmonellosis is an important problem for large animal veterinary teaching hospitals (VTHs). Objective: To describe failure of an Infection Control Program (ICP) that resulted in an outbreak of salmonellosis caused by Salmonella Newport multidrug resistant (MDR)‐AmpC at a large animal VTH. Animals: Sixty‐one animals identified with the outbreak strain of Salmonella . Methods:Retrospective study : Data collected included signalment, presenting complaint, duration of hospitalization, discharge status, and financial information. Phenotypic and genotypic characterization was performed on Salmonella isolates. Results: The outbreak occurred despite an existing ICP; the ICP was reviewed and weaknesses identified. Routine patient surveillance was not performed before or during the outbreak; fecal sampling was triggered only by a patient algorithm based on clinical signs. Sixty‐one animals were infected with the outbreak strain of S . Newport, and the majority were horses (n = 54). Case fatality rate was 36.1%. S . Newport isolates demonstrated high genetic similarity (Dice ≥ 0.96), and all had the MDR‐AmpC phenotype. Environmental persistence of the organism necessitated complete hospital closure, extensive decontamination, and remediation of the facility. A paradigm shift in the relevance of biosecurity in a VTH and the establishment of a stringent ICP were integral components of successful hospital reopening. Conclusions and Clinical Importance: An ineffective ICP resulted in a nosocomial outbreak caused by a MDR S . Newport in a VTH. Closure of a VTH affected all missions of the institution and had substantial financial impact (US$4.12 million).