title: Comparison of molecular and immunological methods for the rapid diagnosis of smear-negative tuberculosis.
abstract: METHODS
  The rapid diagnosis of pulmonary tuberculosis (TB) can be challenging if acid-fast bacilli are not detected by sputum smear microscopy.
  
  
  OBJECTIVE
  To compare the results of the GeneXpert® MTB/RIF assay on a single sputum or bronchoalveolar lavage (BAL) specimen test with local immunodiagnosis from the site of disease using the T-SPOT®.TB assay on BAL (BAL T-SPOT).
  
  
  METHODS
  The Xpert and BAL T-SPOT tests were compared in 96 patients suspected of having sputum smear-negative pulmonary TB admitted to a referral centre in Germany.
  
  
  RESULTS
  BAL T-SPOT identified 10 of 11 patients with pulmonary TB (including 3/4 patients with culture-confirmed TB) with a negative Xpert test. Using Xpert, the sensitivity, specificity and positive and negative likelihood ratios (LRs) were respectively 60.0%, 97.4%, 30.0% and 0.4% in culture-confirmed cases and 42.1%, 97.4%, 21.1% and 0.6% in all TB patients. In contrast, using BAL T-SPOT, the sensitivity, specificity and positive and negative LRs were respectively 80.0%, 62.6%, 2.1% and 0.3% in culture-confirmed cases and 89.4%, 62.6%, 2.4% and 0.2% in all TB patients.
  
  
  CONCLUSIONS
  In sputum smear-negative TB suspects, a positive Xpert result is strongly indicative of culture confirmation; however, a negative result is insufficient to rule out active TB. Where clinical suspicion of pulmonary TB persists despite a negative Xpert result, local immunodiagnosis using T-SPOT on BAL may increase diagnostic accuracy.
authors.affiliation: Clinical Infectious Diseases, Research Center Borstel, Borstel, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Jafari
authors.forename: M
authors.initials: M
authors.lastname: Ernst
authors.forename: B
authors.initials: B
authors.lastname: Kalsdorf
authors.forename: C
authors.initials: C
authors.lastname: Lange
mesh_terms: D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D004269:DNA, Bacterial / Q000032:analysis*; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D059425:Interferon-gamma Release Tests; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D021141:Nucleic Acid Amplification Techniques; D011237:Predictive Value of Tests; D012017:Referral and Consultation; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology
chemical_list: D004269:DNA, Bacterial