title: Rapid diagnosis of smear-negative tuberculosis by bronchoalveolar lavage enzyme-linked immunospot.
abstract: BACKGROUND
  In a large proportion of patients with active pulmonary tuberculosis (pTB), acid-fast bacilli smear results for sputum and bronchial secretions are negative. Detectable growth of Mycobacterium tuberculosis (MTB) in cultures takes several weeks and MTB-specific DNA amplification results on sputum and bronchial secretions are variable in these patients.
  
  
  OBJECTIVE
  We investigated whether a rapid diagnosis of pTB can be established by enumeration of MTB-specific mononuclear cells from bronchoalveolar lavage (BAL) fluid in routine clinical practice.
  
  
  METHODS
  Patients presenting to a tertiary hospital with medical histories and pulmonary infiltrates compatible with tuberculosis, and negative acid-fast bacilli smear results (three) from sputum, were prospectively enrolled in this study. An MTB-specific enzyme-linked immunospot assay (ELISPOT [T-SPOT.TB; Oxford Immunotec, Abingdon, UK]) with early antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) peptides was performed on peripheral blood mononuclear cells (PBMCs) and mononuclear cells from the BAL fluid (BALMCs).
  
  
  RESULTS
  Of 37 patients, 12 were found to have smear-negative pTB and 25 were found to have an alternative diagnosis. Patients with tuberculosis had a median number of 17 ESAT-6-specific cells and 24.5 CFP-10-specific cells per 200,000 PBMCs and 37.5 ESAT-6-specific cells and 49.5 CFP-10-specific cells per 200,000 cells in the BAL fluid. Control patients had a median of 1 ESAT-6-specific cell and 1 CFP-10-specific cell per 200,000 PBMCs and no ESAT-6- and CFP-10-specific cells per 200,000 cells in the BAL fluid (p < 0.0001). All patients with TB but none of the control subjects had more than 5 spot-forming cells per 200,000 BALMCs with either peptide in the BAL fluid ELISPOT.
  
  
  CONCLUSIONS
  Smear-negative pulmonary tuberculosis can be diagnosed rapidly by identification of MTB-specific cells in the BAL fluid.
authors.affiliation: Division of Clinical Infectious Diseases, Research Center Borstel, Parkallee 35, Borstel, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Jafari
authors.forename: Martin
authors.initials: M
authors.lastname: Ernst
authors.forename: Barbara
authors.initials: B
authors.lastname: Kalsdorf
authors.forename: Ulf
authors.initials: U
authors.lastname: Greinert
authors.forename: Roland
authors.initials: R
authors.lastname: Diel
authors.forename: Detlef
authors.initials: D
authors.lastname: Kirsten
authors.forename: Kathleen
authors.initials: K
authors.lastname: Marienfeld
authors.forename: Ajit
authors.initials: A
authors.lastname: Lalvani
authors.forename: Christoph
authors.initials: C
authors.lastname: Lange
mesh_terms: D000328:Adult; D000942:Antigens, Bacterial / Q000032:analysis; D001426:Bacterial Proteins / Q000032:analysis; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D008297:Male; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D011446:Prospective Studies; D013997:Time Factors; D014373:Tuberculin / Q000032:analysis; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D014373:Tuberculin