COMPARISON OF POLYMERASE CHAIN-REACTION AND MICROBIOLOGICAL CULTURE FOR DETECTION OF SALMONELLAE IN EQUINE FECES AND ENVIRONMENTAL-SAMPLES

Objective-To compare the sensitivity of polymerase chain reaction (PCR ) with microbiological culture for detecting salmonellae in equine fec al samples and equine environmental swab specimens. Design-Samples and specimens were tested by PCR and microbiological culture. Sample Popu lation-A fecal sample from each of 152 horses admitted consecutively t o the clinic for evaluation by the outpatient service, 282 fecal sampl es from 110 hospitalized horses that had been submitted to the clinica l microbiology laboratory, and 313 environmental swab specimens were e xamined. Procedure-Each sample and specimen in the study was tested, u sing PCR and microbiological culture. Results of PCR and culture were compared. Results-Significantly (P < 0.001) more fecal samples were po sitive by PCR than by microbiological culture. 26 of 152 (17.1%) fecal samples collected from horses admitted by the outpatient service were positive by PCR and none was positive by culture. 71 of 110 hospitali zed horses were identified as positive by PCR, compared with 11 horses identified as positive by culture. All culture-positive horses were p ositive by PCR. Of the 11 culture-positive horses, 10 (90.9%) were ide ntified as PCR positive after testing of the first sample submitted, c ompared with 7 (63.6%) by culture. All PCR-positive horses were detect ed after a total of 3 samples/horse were submitted, whereas as many as 5 samples/horse was required to identify ail culture-positive horses. 8 of 313 environmental specimens were positive by PCR, and none was p ositive by culture. Conclusion-The PCR method reported here was more s ensitive, more rapid, and required submission of fewer samples or spec imens than did microbiological culture for detecting salmonellae.