Comparison of polymerase chain reaction assays with bacteriologic culture,immunofluorescence, and nucleic acid hybridization for detection of Leptospira borgpetersenii serovar hardjo in urine of cattle

Objective-To compare sensitivity and specificity of various polymerase chai n reaction (PCR) assays for detection of Leptospira borgpetersenii serovar hardjo in bovine urine and to compare results of the optimal PCR assay with results of immunofluorescence, nucleic acid hybridization, and bacteriolog ic culture. Animals-6 heifers. Procedure-Heifers were exposed to serovar hardjo type hardjo-bovis by conju nctival instillation of 10(6) leptospires on 3 successive days. Urine sampl es were collected before and after infection. Sensitivity and specificity o f 5 PCR assays were compared, to determine the optimal assay for use with b ovine urine samples. The optimal PCR assay was then compared with results o f bacteriologic culture, nucleic acid hybridization, and immunofluorescence . Results-A PCR assay with the best combination of specificity (100%) and sen sitivity (91%) was selected for comparison with the other diagnostic tests. Sensitivity for nucleic acid hybridization was 55%, whereas sensitivity fo r bacteriologic culture and immunofluorescence was 89 to 93%. Conclusions and Clinical Relevance-Bacteriologic culture, PCR, and immunofl uorescence were sensitive for detection of Leptospira borgpetersenii serova r hardjo type hardjo-bovis in urine specimens of cattle, but a single techn ique was not the most sensitive for each animal tested. Therefore, the use of 2 techniques in combination is warranted for maximal sensitivity for dia gnosis.