Piengchan SonthayanonWirongrong ChierakulVanaporn WuthiekanunJanjira ThaipadungpanitThareerat KalambahetiSiriphan BoonsilpPremjit AmornchaiLee D. SmytheDirek LimmathurotsakulNicholas P. DaySharon J. PeacockMahidol UniversityOrganisation Mondiale de la SanteNuffield Department of Clinical MedicineUniversity of Cambridge2018-05-032018-05-032011-04-01American Journal of Tropical Medicine and Hygiene. Vol.84, No.4 (2011), 614-620000296372-s2.0-79958007507https://repository.li.mahidol.ac.th/handle/20.500.14594/12062There is a lack of diagnostic tests for leptospirosis in technology-restricted settings. We developed loop-mediated isothermal amplification (LAMP) specific for the 16S ribosomal RNA gene (rrs) of pathogenic and intermediate group Leptospira species. The lower limit of detection was 10 genomic equivalents/reaction, and analytical specificity was high; we observed positive reactions for pathogenic/intermediate groups and negative reactions for non-pathogenic Leptospira species and other bacterial species. We evaluated this assay in Thailand by using a case-control study of 133 patients with laboratory-proven leptospirosis and 133 patients with other febrile illnesses. Using admission blood, we found that the rrs LAMP showed positive results in 58 of 133 cases (diagnostic sensitivity = 43.6, 95% confidence interval [CI] = 35.0-52.5) and in 22 of 133 controls (diagnostic specificity = 83.5, 95% CI = 76.0-89.3). Sensitivity was high for 39 patients who were culture positive for Leptospira spp. (84.6, 95% CI = 69.5-94.1). The rrs LAMP can provide an admission diagnosis in approximately half of patients with leptospirosis, but its clinical utility is reduced by a lower specificity. Copyright © 2011 by The American Society of Tropical Medicine and Hygiene.Mahidol UniversityImmunology and MicrobiologyMedicineArticleSCOPUS10.4269/ajtmh.2011.10-0473