title: Diagnostic accuracy of real-time PCR assays targeting 16S rRNA and lipL32 genes for human leptospirosis in Thailand: a case-control study.
abstract: BACKGROUND
  Rapid PCR-based tests for the diagnosis of leptospirosis can provide information that contributes towards early patient management, but these have not been adopted in Thailand. Here, we compare the diagnostic sensitivity and specificity of two real-time PCR assays targeting rrs or lipL32 for the diagnosis of leptospirosis in northeast Thailand.
  
  
  RESULTS
  A case-control study of 266 patients (133 cases of leptospirosis and 133 controls) was constructed to evaluate the diagnostic sensitivity and specificity (DSe & DSp) of both PCR assays. The median duration of illness prior to admission of cases was 4 days (IQR 2-5 days; range 1-12 days). DSe and DSp were determined using positive culture and/or microscopic agglutination test (MAT) as the gold standard. The DSe was higher for the rrs assay than the lipL32 assay (56%, (95% CI 47-64%) versus 43%, (95% CI 34-52%), p<0.001). No cases were positive for the lipL32 assay alone. There was borderline evidence to suggest that the DSp of the rrs assay was lower than the lipL32 assay (90% (95% CI 83-94%) versus 93%, (95%CI 88-97%), p = 0.06). Nine controls gave positive reactions for both assays and 5 controls gave a positive reaction for the rrs assay alone. The DSe of the rrs and lipL32 assays were high in the subgroup of 39 patients who were culture positive for Leptospira spp. (95% and 87%, respectively, p = 0.25).
  
  
  CONCLUSIONS
  Early detection of Leptospira using PCR is possible for more than half of patients presenting with leptospirosis and could contribute to individual patient care.
authors.affiliation: Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. janjira@tropmedres.ac
authors.forename: Janjira
authors.initials: J
authors.lastname: Thaipadungpanit
authors.forename: Janjira
authors.initials: J
authors.lastname: Thaipadunpanit
authors.forename: Wirongrong
authors.initials: W
authors.lastname: Chierakul
authors.forename: Vanaporn
authors.initials: V
authors.lastname: Wuthiekanun
authors.forename: Direk
authors.initials: D
authors.lastname: Limmathurotsakul
authors.forename: Premjit
authors.initials: P
authors.lastname: Amornchai
authors.forename: Siriphan
authors.initials: S
authors.lastname: Boonslip
authors.forename: Lee D
authors.initials: LD
authors.lastname: Smythe
authors.forename: Roongrueng
authors.initials: R
authors.lastname: Limpaiboon
authors.forename: Alex R
authors.initials: AR
authors.lastname: Hoffmaster
authors.forename: Nicholas P J
authors.initials: NP
authors.lastname: Day
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Peacock
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D016022:Case-Control Studies; D004269:DNA, Bacterial / Q000032:analysis; D042241:Early Diagnosis; D006801:Humans; D007919:Leptospira / Q000235:genetics / Q000302:isolation & purification*; D007922:Leptospirosis / Q000175:diagnosis*; D008074:Lipoproteins / Q000235:genetics; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods* / Q000592:standards; D012335:RNA, Ribosomal / Q000032:analysis; D012336:RNA, Ribosomal, 16S; D012680:Sensitivity and Specificity; D013785:Thailand; D055815:Young Adult
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004269:DNA, Bacterial; C406589:LipL32 protein, Leptospira; D008074:Lipoproteins; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S