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 24 h 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-organ isms Although Salmonella spp were not cultured from fresh feces the organism was cultured from 6/911 (06%) of broth-enriched samples The bacterial load in enriched samples varied from 3 to 861 037 salmonella invA gene copies/mu L 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 (c) 2009 Elsevier Ltd All rights reserved