title: Clinical value of IS6110-based loop-mediated isothermal amplification for detection of Mycobacterium tuberculosis complex in respiratory specimens.
abstract: OBJECTIVE
  A fundamental to global tuberculosis (TB) control is timely and accurate diagnosis of infectious cases of the disease. Among various methods, techniques based on nucleic acid amplification are the ones with promising prospects. The present study evaluates the diagnostic value of the recently developed IS6110-based loop-mediated isothermal amplification (LAMP) for detection of Mycobacterium tuberculosis complex (MTBC) in sputum specimens.
  
  
  METHODS
  In this cross-sectional study (2008-2009), IS6110-LAMP was evaluated on 101 sputum specimens from 93 highly suspected TB patients and compared to Amplicor MTB test and in-house IS6110-PCR and -nested PCR assays. Culture results or clinical recovery following anti-TB therapy was considered as a reference to prove the TB cases.
  
  
  RESULTS
  The overall sensitivity of IS6110-LAMP, Amplicor, nPCR, and PCR were respectively 89.6% (69/77 specimens; 95% confidence interval [CI], 80.5-95.4%), 76.6% (59/77 specimens; CI, 65.6-85.5%), 79.2% (61/77 specimens; CI, 68.5-87.6%) and 59.7% (46/77 specimens; CI, 47.9-70.8%). The specificity and positive predictive value (PPV) were 100% for all the tests, and the negative predictive value (NPV) of IS6110-LAMP, Amplicor, nPCR, and PCR were respectively 75%, 57.1%, 60%, and 43.6%. There was an excellent overall agreement between LAMP and nPCR (k 0.828), and between LAMP and Amplicor (k 0.746), in addition to a better tolerance of IS6110-LAMP to inhibitors present in clinical specimens.
  
  
  CONCLUSIONS
  The better diagnostic performance of IS6110-LAMP compared to Amplicor (p = 0.009), nPCR (p = 0.013) and PCR (p < 0.0001) besides its rapidity, simplicity, and cost-effectiveness makes it a valuable method for the detection of MTBC in clinical samples, particularly in resource-limited settings.
authors: Antimicrobial Resistance Research Center, Department of Medical Microbiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. ehsanaryan@hotmail.com
authors: Ehsan
authors: E
authors: Aryan
authors: Manoochehr
authors: M
authors: Makvandi
authors: Ahmad
authors: A
authors: Farajzadeh
authors: Kris
authors: K
authors: Huygen
authors: Amir-Hooshang
authors: AH
authors: Alvandi
authors: Mohammad-Mehdi
authors: MM
authors: Gouya
authors: Ali
authors: A
authors: Sadrizadeh
authors: Marta
authors: M
authors: Romano
mesh_terms: D003430:Cross-Sectional Studies; D006801:Humans; D058889:Molecular Typing / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000382:microbiology*