Salmonella enterica serovar Oranienburg outbreak in a veterinary medical teaching hospital with evidence of nosocomial and on-farm transmission.

The research article highlights an outbreak of Salmonella enterica serovar Oranienburg in a veterinary hospital, where both hospital and on-farm transmission seemed to be significant sources of infection. Steps to improve biosecurity led to an end to the outbreak.

Study Objectives and Methods

• The study aimed to explore an outbreak of salmonellosis caused by Salmonella enterica serovar Oranienburg in a veterinary hospital. The researchers sought to understand its unique features to help prevent such nosocomial outbreaks in the future.
• The research involved a retrospective investigation of patients infected by this strain of salmonella. The team analyzed data from patients who tested positive for Salmonella Oranienburg between January 1, 2006, and June 1, 2011.
• The study used historical, clinical, and pulsed-field gel electrophoresis (PFGE) data. PFGE is a laboratory technique used for separating large molecules of DNA, usually for genetic and epidemiological studies.

Key Findings

• The study identified the Salmonella Oranienburg in 20 horses, five alpacas, and three cows, admitted to the hospital between August 2006 and January 2008.
• Most patients appeared to have contracted the infection either within the hospital (nosocomial transmission) or on the farm (on-farm transmission). The study affirmed this using molecular subtyping results, along with supportive epidemiological data.
• Interpretation of PFGE results was challenging due to the closeness of several Salmonella Oranienburg subtypes. Further, a significant percentage of cases tested positive for the bacteria within 24 hours of admission.
• These patients initially seemed to have brought new Salmonella infections into the hospital. However, more in-depth medical record analysis revealed links to the hospital following the index case.

Conclusion and Implications

• The outbreak ended after heightened biosecurity measures were implemented, with no known cases or positive environmental samples found after January 2008.
• This study suggests that a Salmonella-positive culture result within 24 hours of admission does not necessarily mean the infection was sourced outside the hospital.
• It further emphasizes the significant role veterinary teaching hospitals play in being points of Salmonella infection and facilitating transmission outside the hospital setting.