Siriphan BoonsilpJanjira Thaipadungpanitจันทร์จิรา ไทยผดุงพานิชPremjit Amornchaiเปรมจิตต์ อมรชัยVanaporn WuthiekanunWirongrong ChierakulDirek Limmathurotsakulดิเรก ลิ้มมธุรสกุลDay, Nicholas P.Peacock, Sharon J.Mahidol University. Faculty of Tropical Medicine. Mahidol-Oxford Tropical Medicine Research Unit2012-10-112016-09-292012-10-112016-09-2920112012-10-112011-12-13Boonsilp S, Thaipadungpanit J, Amornchai P, Wuthiekanun V, Chierakul W, Limmathurotsakul D, et al. Molecular detection and speciation of pathogenic Leptospira spp. in blood from patients with culture-negative leptospirosis. BMC Infect Dis. 2011 Dec 13;11:338.1471-2334 (electronic)https://repository.li.mahidol.ac.th/handle/20.500.14594/740BACKGROUND: 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.engMahidol UniversityBacterial typing techniquesDNA, bacterialLeptospiraProspective studiesOpen Access articleMolecular detection and speciation of pathogenic Leptospira spp. in blood from patients with culture-negative leptospirosisResearch ArticleBMC infectious diseases10.1186/1471-2334-11-338