title: Comparison of loop-mediated isothermal amplification assay and smear microscopy with culture for the diagnostic accuracy of tuberculosis.
abstract: Tuberculosis (TB) caused by Mycobacterium tuberculosis is one of the leading causes of death from infectious diseases worldwide. Sputum smear microscopy remains the most widely available pulmonary TB diagnostic tool particularly in resource limited settings. A highly sensitive diagnostic with minimal infrastructure, cost and training is required. Hence, we assessed the diagnostic performance of Loop-mediated isothermal amplification (LAMP) assay in detecting M.tuberculosis infection in sputum sample compared to LED fluorescent smear microscopy and culture.
  
  
  
  A cross-sectional study was conducted at the University of Gondar Hospital from June 01, 2015 to August 30, 2015. Pulmonary TB diagnosis using sputum LED fluorescence smear microscopy, TB-LAMP assay and culture were done. A descriptive analysis was used to determine demographic characteristics of the study participants. Analysis of sensitivity and specificity for smear microscopy and TB-LAMP compared with culture as a reference test was performed. Cohen's kappa was calculated as a measure of agreement between the tests.
  
  
  
  A total of 78 pulmonary presumptive TB patients sputum sample were analyzed. The overall sensitivity and specificity of LAMP were 75 and 98%, respectively. Among smear negative sputum samples, 33.3% sensitivity and 100% specificity of LAMP were observed. Smear microscopy showed 78.6% sensitivity and 98% specificity. LAMP and smear in series had sensitivity of 67.8% and specificity of 100%. LAMP and smear in parallel had sensitivity of 85.7% and specificity of 96%. The agreement between LAMP and fluorescent smear microscopy tests was very good (κ = 0.83, P-value ≤0.0001).
  
  
  
  TB-LAMP showed similar specificity but a slightly lower sensitivity with LED fluorescence microscopy. The specificity of LAMP and smear microscopy in series was high. The sensitivity of LAMP was insufficient for smear negative sputum samples.
authors.affiliation: Department of Medical Microbiology, School of Biomedical and Laboratory sciences, CMHS, University of Gondar, P.O. box 196, Gondar, Ethiopia.
authors.forename: Baye
authors.initials: B
authors.lastname: Gelaw
authors.affiliation: Department of Microbiology, Parasitology and Immunology, Faculty of Medicine, Addis Ababa University, Addis Ababa, Ethiopia.|School of Medicine, Flinders University, Bedford Park, SA, 5042, Adelaide, Australia.
authors.forename: Yitayal
authors.initials: Y
authors.lastname: Shiferaw
authors.affiliation: Department of Medical Microbiology, School of Biomedical and Laboratory sciences, CMHS, University of Gondar, P.O. box 196, Gondar, Ethiopia.
authors.forename: Marta
authors.initials: M
authors.lastname: Alemayehu
authors.affiliation: Department of Medical Microbiology, School of Biomedical and Laboratory sciences, CMHS, University of Gondar, P.O. box 196, Gondar, Ethiopia. abezew@gmail.com.
authors.forename: Abate Assefa
authors.initials: AA
authors.lastname: Bashaw
mesh_terms: D000293:Adolescent; D000328:Adult; D001681:Biological Assay; D003430:Cross-Sectional Studies; D046508:Culture Techniques / Q000379:methods*; D005002:Ethiopia; D005260:Female; D006295:Health Resources; D006761:Hospitals; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*; D055815:Young Adult
keywords: Culture; Loop-mediated isothermal amplification; Smear microscopy; Tuberculosis