title: Diagnostic yield of Bronchoalveolar Lavage gene Xpert in smear-negative and sputum-scarce pulmonary tuberculosis.
abstract: OBJECTIVE
  To measure the diagnostic yield of Bronchoalveolar Lavage (BAL) gene Xpert (Xpert MTB/RIF assay), to detect Mycobacterium tuberculosis (MTB) and rifampicin resistance and compare it with that of mycobacterial cultures in a suspected case of pulmonary tuberculosis.
  
  
  METHODS
  An analytical study.
  
  
  METHODS
  Department of Pulmonology, Fauji Foundation Hospital (FFH), Rawalpindi, from December 2012 to August 2013.
  
  
  METHODS
  BAL specimens of 93 patients with suspected pulmonary tuberculosis with smear-negative or sputumscarce disease, who presented to the Department of Pulmonology, FFH, Rawalpindi were inducted. A smear-negative case was one in whom three consecutive early morning sputum samples did not reveal acid fast bacilli when examined by microscopy with Zeihl Nelson (ZN) stain. Patients who had sputum amount less than 1 ml were defined to have sputumscarce disease. The same was evaluated with ZN stain, gene Xpert and mycobacterial cultures. Sensitivity analysis was carried out using culture as the gold standard.
  
  
  RESULTS
  The frequency of positive mycobacterial cultures was 85 (91.4%). The sensitivity, specificity, positive predictive value and negative predictive values of BAL gene Xpert to detect Mycobacterium tuberculosis were 91.86%, 71.42%, 97.53% and 41.66% respectively. Xpert MTB/RIF assay had a sensitivity and specificity of 83.33% and 100% to detect rifampicin resistance.
  
  
  CONCLUSIONS
  Bronchoalveolar lavage gene Xpert had a superior diagnostic yield in patients with either smear-negative or sputum-scarce pulmonary tuberculosis. Hence a positive Xpert MTB/RIF assay may be a useful adjunct to diagnosis and detection of MDR-TB in bronchoalveolar lavage specimens.
authors.affiliation: Department of Pulmonology, Fauji Foundation Hospital, Rawalpindi.
authors.forename: Kanwal Fatima
authors.initials: KF
authors.lastname: Khalil
authors.affiliation: Department of Pathology, Fauji Foundation Hospital, Rawalpindi.
authors.forename: Tariq
authors.initials: T
authors.lastname: Butt
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000904:Antibiotics, Antitubercular / Q000627:therapeutic use*; D001426:Bacterial Proteins; D018893:Bronchoalveolar Lavage; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology*; D012321:DNA-Directed RNA Polymerases; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D021141:Nucleic Acid Amplification Techniques; D012293:Rifampin / Q000627:therapeutic use*; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*; D018088:Tuberculosis, Multidrug-Resistant; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology
chemical_list: D000904:Antibiotics, Antitubercular; D001426:Bacterial Proteins; C505805:rpoB protein, Mycobacterium tuberculosis; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin