Comparison of real-time PCR, bacteriologic culture and fluorescent antibody test for the detection of Leptospira borgpetersenii in urine of naturally infected cattle

Authors: Nally, Jarlath; AHMED, A - University Of Amsterdam; Putz, Ellie; Palmquist, Debra; GORIS, M - University Of Amsterdam

Submitted to: Veterinary Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2020
Publication Date: 5/15/2020
Publication URL: https://handle.nal.usda.gov/10113/7019845
Citation: Nally, J.E., Ahmed, A., Putz, E.J., Palmquist, D.E., Goris, M. 2020. Comparison of real-time PCR, bacteriologic culture and fluorescent antibody test for the detection of Leptospira borgpetersenii in urine of naturally infected cattle. Veterinary Sciences. 7(2):66. https://doi.org/10.3390/vetsci7020066.
DOI: https://doi.org/10.3390/vetsci7020066

Interpretive Summary: Bovine leptospirosis results in abortion, stillbirth, premature birth, reproductive failure and milk drop syndrome. The causative agent, pathogenic leptospires, are excreted from kidneys of infected cows via urine into the environment where they can continue to survive in suitable moist conditions and maintain disease transmission to other animals. The gold standard test to detect cattle that are excreting leptospires in urine is culture. However, culture is difficult, costly, requires specialized growth media and takes weeks to months for a positive results. Alternative assays exist including a molecular PCR (polymerase chain reaction) assay and a fluorescent antibody test (FAT). The performance of culture, PCR and FAT was compared to each other using known positive and negative bovine urine samples. Results demonstrate that no single assay is best, and that the use of at least two assays are recommended to detect leptospires in bovine urine samples.

Technical Abstract: Cattle are susceptible to infection with multiple serovars of pathogenic leptospires, resulting in abortion, stillbirth, premature birth, reproductive failure and milk drop syndrome. Cattle also act as a reservoir host for L. borgpetersenii serovar Hardjo which is excreted from renal tubules via urine into the environment where it persists in suitable moist conditions. Our previous work demonstrated that 7 percent of urine samples from beef cattle were positive for L. borgpetersenii serovar Hardjo by culture and/or the fluorescent antibody test (FAT). In this study, a real-time PCR (rtPCR) assay was applied to determine the relative performance of rtPCR based detection of L. borgpetersenii serovar Hardjo compared to previously reported culture and FAT techniques. Of 42 bovine urine samples positive for leptospires by culture and/or FAT, 60 percent (25/42) were positive by rtPCR. Of 22 culture-positive samples, 91 percent (20/22) were rtPCR positive. Of 32 FAT-positive samples, 50 percent (16/32) were rtPCR positive. For 10 samples that were culture-positive but FAT-negative, 90 percent (9/10) were rtPCR positive. For 20 samples that were FAT-positive but culture-negative, 25 percent (5/20) were rtPCR positive. Collectively, these results indicate that no single assay is optimal, and the use of more than one assay to detect leptospires in urine from naturally infected cattle is recommended.