title: Comparison of the efficacies of loop-mediated isothermal amplification, fluorescence smear microscopy and culture for the diagnosis of tuberculosis.
abstract: BACKGROUND
  Despite the advent of novel diagnostic techniques, smear microscopy remains as the most practical test available in resource-limited settings for tuberculosis (TB) diagnosis. Due to the low sensitivity of microscopy and the long time required for culture, feasible and accessible rapid diagnostic methods are urgently needed. Loop-mediated Isothermal Amplification (LAMP) is a promising nucleic-acid amplification assay, which could be accessible, cost-effective and more suited for use with unpurified samples.
  
  
  RESULTS
  In the current study, the objective was to assess the efficacy of a LAMP assay for tuberculosis compared with fluorescence smear microscopy as well as Löwenstein-Jensen (LJ) and Mycobacteria Growth Indicator Tube (MGIT) cultures for the diagnosis of pulmonary tuberculosis using sputum samples. Smear microscopy and culture were performed for decontaminated and concentrated sputum from TB suspects and the LAMP was also performed on these specimens. The LAMP and smear microscopy were compared, in series and in parallel, to culture. LAMP and smear microscopy showed sensitivities of 79.5% and 82.1% respectively and specificities of 93.8% and 96.9% respectively, compared to culture. LAMP and smear in series had sensitivity and specificity of 79.5% and 100.0% respectively. LAMP and smear in parallel had sensitivity and specificity of 82.1% and 90.6% respectively.
  
  
  CONCLUSIONS
  The overall efficacies of LAMP and fluorescence smear microscopy in the current study were high and broadly similar. LAMP and smear in series had high specificity (100.0%) and can be used as a rule-in test combination. However, the performance of LAMP in smear negative samples was found to be insufficient.
authors.affiliation: Division of Infectious Disease, St John's Research Institute, Bangalore, India.
authors.forename: Geojith
authors.initials: G
authors.lastname: George
authors.forename: Prem
authors.initials: P
authors.lastname: Mony
authors.forename: John
authors.initials: J
authors.lastname: Kenneth
mesh_terms: D046508:Culture Techniques / Q000379:methods*; D006801:Humans; D008856:Microscopy, Fluorescence / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D013183:Sputum / Q000382:microbiology; D018511:Systems Integration; D014376:Tuberculosis / Q000175:diagnosis* / Q000382:microbiology*