title: Comparison of TB-LAMP, GeneXpert MTB/RIF and culture for diagnosis of pulmonary tuberculosis in The Gambia.
abstract: BACKGROUND
  Diagnosis of tuberculosis (TB) remains difficult, particularly in resource-limited settings. The development of nucleic acid-based tests for detection of Mycobacterium tuberculosis complex (MTBC) has significantly increased sensitivity compared to conventional smear microscopy and provides results within a matter of hours compared to weeks for the current gold-standard, liquid culture.
  
  
  METHODS
  In this study we performed side-by-side comparison of mycobacterial detection assays on sputum samples from 285 subjects presenting with symptoms suggestive of TB in The Gambia and a cross-sectional cohort of 156 confirmed TB patients with a median of 2 months of treatment. A novel assay, Loop-Mediated Amplification test for TB (TB-LAMP), was compared to smear microscopy, MGIT culture and GeneXpert MTB/RIF for all samples.
  
  
  RESULTS
  When culture was used as the reference standard, we found an overall sensitivity for TB-LAMP of 99% (95% CI: 94.5-99.8) and specificity of 94% (95% CI: 89.3-96.7). When latent class analysis was performed, TB-LAMP had 98.6% (95% CI: 95.9-100) sensitivity and 99% (95% CI: 98.2-100) specificity compared to 91.1% (95% CI: 86.1-96) sensitivity and 100% (95% CI: 98.2-100) specificity for MGIT culture. GeneXpert had the highest sensitivity 99.1% (95% CI: 97.1-100) but the lowest specificity 96% (95% CI: 92.6-98.3). Both TB-LAMP and GeneXpert showed high sensitivity and specificity regardless of age or strain of infection.
  
  
  CONCLUSIONS
  Our findings show the diagnostic utility of both GeneXpert and TB-LAMP in The Gambia. Whilst TB-LAMP requires less infrastructure, it is unable to detect drug-resistant patterns and therefore would be most suitable as a screening test for new TB cases in peripheral health clinics.
authors.affiliation: Vaccines and Immunity Theme, Medical Research Council (MRC) Unit, Fajara, Gambia.
authors.forename: Adama L
authors.initials: AL
authors.lastname: Bojang
authors.affiliation: Vaccines and Immunity Theme, Medical Research Council (MRC) Unit, Fajara, Gambia.
authors.forename: Francis S
authors.initials: FS
authors.lastname: Mendy
authors.affiliation: Vaccines and Immunity Theme, Medical Research Council (MRC) Unit, Fajara, Gambia.
authors.forename: Leopold D
authors.initials: LD
authors.lastname: Tientcheu
authors.affiliation: Vaccines and Immunity Theme, Medical Research Council (MRC) Unit, Fajara, Gambia.
authors.forename: Jacob
authors.initials: J
authors.lastname: Otu
authors.affiliation: Vaccines and Immunity Theme, Medical Research Council (MRC) Unit, Fajara, Gambia.
authors.forename: Martin
authors.initials: M
authors.lastname: Antonio
authors.affiliation: Vaccines and Immunity Theme, Medical Research Council (MRC) Unit, Fajara, Gambia.
authors.forename: Beate
authors.initials: B
authors.lastname: Kampmann
authors.affiliation: Vaccines and Immunity Theme, Medical Research Council (MRC) Unit, Fajara, Gambia.
authors.forename: Schadrac
authors.initials: S
authors.lastname: Agbla
authors.affiliation: Vaccines and Immunity Theme, Medical Research Council (MRC) Unit, Fajara, Gambia. Electronic address: jsutherland@mrc.gm.
authors.forename: Jayne S
authors.initials: JS
authors.lastname: Sutherland
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001431:Bacteriological Techniques / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D005714:Gambia; D006801:Humans; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D009161:Mycobacterium / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*; D055815:Young Adult
keywords: Diagnosis; Gambia; GeneXpert; Sputum culture; TB-LAMP; Tuberculosis; West Africa