title: Loop-mediated isothermal amplification as alternative to PCR for the diagnosis of extra-pulmonary tuberculosis.
abstract: BACKGROUND
  The main challenge in combatting extra-pulmonary tuberculosis (EPTB) is the lack of a rapid, reliable and inexpensive diagnostic test for the detection of Mycobacterium tuberculosis.
  
  
  OBJECTIVE
  To evaluate the diagnostic potential of an L-serine dehydratase gene (sdaA) loop-mediated isothermal amplification (LAMP) assay for the detection of M. tuberculosis in clinical specimens from presumptive EPTB patients.
  
  
  METHODS
  An in-house sdaA LAMP assay was used to analyse clinical specimens (n = 315) for the diagnosis of EPTB compared with culture and the composite reference standard (CRS) comprising culture and polymerase chain reaction (PCR) using insertion sequence (IS) 6110 and mpb64 as target genes.
  
  
  RESULTS
  The sdaA LAMP assay showed the highest sensitivity (93.3%) in comparison to culture; the sensitivity of IS6110 PCR, mpb64 and sdaA PCR assay was respectively 80%, 86.7% and 90%. In comparison to CRS, the LAMP assay had a sensitivity of 92.5% and a specificity of 99.2%, with a high positive (121.11) and a low negative likelihood ratio (0.08).
  
  
  CONCLUSIONS
  Due to its speed, simplicity, sensitivity and specificity, the sdaA LAMP assay is a potential diagnostic test for the diagnosis of EPTB, particularly in resource-limited settings.
authors.affiliation: Dr B R Ambedkar Centre for Biomedical Research, University of Delhi, Delhi, India.
authors.forename: D
authors.initials: D
authors.lastname: Joon
authors.affiliation: Shri Guru Tegh Bahadur Khalsa College, University of Delhi, Delhi, India.
authors.forename: M
authors.initials: M
authors.lastname: Nimesh
authors.affiliation: Dr B R Ambedkar Centre for Biomedical Research, University of Delhi, Delhi, India.
authors.forename: D
authors.initials: D
authors.lastname: Saluja
mesh_terms: D006801:Humans; D016013:Likelihood Functions; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000175:diagnosis*