Use of quantitative real-time PCR for the detection of Salmonella spp. in fecal samples from horses at a veterinary teaching hospital.
A quantitative real-time (RT)-PCR assay was developed to detect Salmonella spp. in the feces of 911 equine species admitted to a veterinary hospital. Fresh feces and feces enriched for 24h in selenite broth were assessed by conventional culture and by RT-PCR targeting the Salmonella invA gene. The detection limit for the RT-PCR assay was 3 and 10 organisms, respectively, when spiked samples were purified from selenite broth and feces. The analytical specificity was 100% based on the detection of a panel of 40 salmonella serotypes from five serogroups and the lack of cross-reactivity with non-related micro-organisms. Although Salmonella spp. were not cultured from fresh feces, the organism was cultured from 6/911 (0.6%) of broth-enriched samples. The bacterial load in enriched samples varied from 3 to 861,037 salmonella invA gene copies/μL DNA. The RT-PCR assay had an overall relative accuracy of 98%, a relative sensitivity of 100% and a relative specificity of 98%, when compared to conventional culture. The judicious use of such a RT-PCR method has the potential to reduce the risk of nosocomial infections such as salmonellosis through the provision of highly accurate and rapid pathogen detection.
Pusterla
Nicola
N
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, USA. npusterla@ucdavis.edu
Byrne
Barbara A
BA
Hodzic
Emir
E
Mapes
Samantha
S
Jang
Spencer S
SS
Magdesian
K Gary
KG
D000818:Animals; D046508:Culture Techniques / Q000379:methods / Q000662:veterinary; D004269:DNA, Bacterial / Q000032:analysis; D005243:Feces / Q000382:microbiology*; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis* / Q000382:microbiology; D006736:Horses; D006762:Hospitals, Animal; D006784:Hospitals, Teaching; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary*; D012475:Salmonella / Q000235:genetics / Q000302:isolation & purification*; D012481:Salmonella Infections, Animal / Q000175:diagnosis* / Q000382:microbiology; D012680:Sensitivity and Specificity
D004269:DNA, Bacterial