Comparison of Salmonella enterica serotype Infantis isolates from a veterinary teaching hospital.
OBJECTIVE
To compare Salmonella enterica serotype Infantis isolates obtained from patients or the environment of a veterinary teaching hospital over a period of 9 years following a nosocomial outbreak to determine whether isolates were epidemiologically related or represented unrelated introductions into the hospital environment.


RESULTS
Fifty-six S. Infantis isolates were compared based on their phenotypic (antimicrobial drug [AMD] 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 AMD, with 67.8% showing resistance to >5 AMD. The majority (74.1%) of isolates tested contained type 1 integrons.


CONCLUSIONS
Results strongly suggest that there was nosocomial transmission of S. 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.


CONCLUSIONS
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.
Dunowska
M
M
Animal Population Health Institute, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
Morley
P S
PS
Traub-Dargatz
J L
JL
Davis
M A
MA
Patterson
G
G
Frye
J G
JG
Hyatt
D R
DR
Dargatz
D A
DA
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003428:Cross Infection / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D006762:Hospitals, Animal; D006801:Humans; D032023:Integrons / Q000235:genetics; D008826:Microbial Sensitivity Tests / Q000379:methods; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods; D012189:Retrospective Studies; D012480:Salmonella Infections / Q000382:microbiology*; D012481:Salmonella Infections, Animal / Q000382:microbiology; D019779:Salmonella enterica / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial