Molecular detection and speciation of pathogenic Leptospira spp. in blood from patients with culture-negative leptospirosis
Day, Nicholas P.
Peacock, Sharon J.
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Boonsilp, S., Thaipadungpanit, J., Amornchai, P., Wuthiekanun, V., Chierakul, W., Limmathurotsakul, D., Day, N. P., & et al. (2011). Molecular detection and speciation of pathogenic Leptospira spp. in blood from patients with culture-negative leptospirosis.
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Abstract Background Pathogenic Leptospira spp. present in the blood of patients with leptospirosis during the first week of symptoms can be detected using culture or PCR. A proportion of patients who are positive by PCR are negative by culture. Leptospira spp. are fastidious bacteria, and we hypothesized that a false-negative culture result may represent infection with a distinct bacterial subset that fail to grow in standard culture medium. Methods We evaluated our hypothesis during a prospective study of 418 consecutive patients presenting to a hospital in northeast Thailand with an acute febrile illness. Admission blood samples were taken for Leptospira culture and PCR. A single tube nested PCR that amplified a region of the rrs gene was developed and applied, amplicons sequenced and a phylogenetic tree reconstructed. Results 39/418 (9%) patients were culture-positive for Leptospira spp., and 81/418 (19%) patients were culture-negative but rrs PCR-positive. The species associated with culture-positive leptospirosis (37 L. interrogans and 2 L. borgpetersenii) were comparable to those associated with culture-negative, PCR-positive leptospirosis (76 L. interrogans, 4 L. borgpetersenii, 1 unidentified, possibly new species). Conclusion Molecular speciation failed to identify a unique bacterial subset in patients with culture-negative, PCR-positive leptospirosis. The rate of false-negative culture was high, and we speculate that antibiotic pre-treatment is the most likely explanation for this.
This record's URL: http://www.dspace.cam.ac.uk/handle/1810/241754
Rights Holder: Boonsilp et al.; licensee BioMed Central Ltd.