title: The utility of Xpert MTB/RIF performed on bronchial washings obtained in patients with suspected pulmonary tuberculosis in a high prevalence setting.
abstract: BACKGROUND
  Xpert MTB/RIF has been shown to have a superior sensitivity to microscopy for acid fast bacilli (AFB) in sputum and has been recommended as a standard first line investigation for pulmonary tuberculosis (PTB). Bronchoscopy is a valuable tool in diagnosing PTB in sputum negative patients. There is limited data on the utility of Xpert MTB/RIF performed on bronchial lavage specimens. Our aim was to evaluate the diagnostic efficiency of Xpert MTB/RIF performed on bronchial washings in sputum scarce/negative patients with suspected PTB.
  
  
  METHODS
  All patients with a clinical and radiological suspicion of PTB who underwent bronchoscopy between January 2013 and April 2014 were included. The diagnostic efficiencies of Xpert MTB/RIF and microscopy for AFB were compared to culture for Mycobacterium tuberculosis.
  
  
  RESULTS
  Thirty nine of 112 patients were diagnosed with culture-positive PTB. Xpert MTB/RIF was positive in 36/39 with a sensitivity of 92.3% (95% CI 78-98%) for PTB, which was superior to that of smear microscopy (41%; 95% CI 26.0-57.8%, p = 0.005). The specificities of Xpert MTB/RIF and smear microscopy were 87.7% (95% CI 77.4-93.9%) and 98.6% (95% CI 91.6%-99.9%) respectively. Xpert MTB/RIF had a positive predictive value of 80% (95% CI; 65-89.9%) and negative predictive value of 95.5% (95% CI 86.6-98.8%). 3/9 patients with Xpert MTB/RIF positive culture negative results were treated for PTB based on clinical and radiological findings.
  
  
  CONCLUSIONS
  Xpert MTB/RIF has a higher sensitivity than smear microscopy and similar specificity for the immediate confirmation of PTB in specimens obtained by bronchial washing, and should be utilised in patients with a high suspicion of pulmonary tuberculosis.
authors.affiliation: Divisions of Pulmonology, Department of Medicine, Stellenbosch University, PO Box 19063, 7505, Cape Town, South Africa. dabarnard@live.com.|Tygerberg Academic Hospital, Cape Town, South Africa. dabarnard@live.com.
authors.forename: Dewald A
authors.initials: DA
authors.lastname: Barnard
authors.affiliation: Divisions of Pulmonology, Department of Medicine, Stellenbosch University, PO Box 19063, 7505, Cape Town, South Africa. eirusen@sun.ac.za.|Tygerberg Academic Hospital, Cape Town, South Africa. eirusen@sun.ac.za.
authors.forename: Elvis M
authors.initials: EM
authors.lastname: Irusen
authors.affiliation: Divisions of Pulmonology, Department of Medicine, Stellenbosch University, PO Box 19063, 7505, Cape Town, South Africa. cdchar@sun.ac.za.|Tygerberg Academic Hospital, Cape Town, South Africa. cdchar@sun.ac.za.
authors.forename: Johannes W
authors.initials: JW
authors.lastname: Bruwer
authors.affiliation: Kuils River Hospital, Cape Town, South Africa. dp.krrc@mwebbiz.co.za.
authors.forename: Danté
authors.initials: D
authors.lastname: Plekker
authors.affiliation: Tygerberg Academic Hospital, Cape Town, South Africa. awhitelaw@sun.ac.za.|Division of Medical Microbiology and Immunology, Department of Pathology, Stellenbosch University, Cape Town, South Africa. awhitelaw@sun.ac.za.|National Health Laboratory Services, Cape Town, South Africa. awhitelaw@sun.ac.za.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Whitelaw
authors.affiliation: Ampath Laboratories, Cape Town, South Africa. deetlefsj@ampath.co.za.
authors.forename: Jacobus D
authors.initials: JD
authors.lastname: Deetlefs
authors.affiliation: Divisions of Pulmonology, Department of Medicine, Stellenbosch University, PO Box 19063, 7505, Cape Town, South Africa. coeniefn@sun.ac.za.|Tygerberg Academic Hospital, Cape Town, South Africa. coeniefn@sun.ac.za.
authors.forename: Coenraad F N
authors.initials: CF
authors.lastname: Koegelenberg
mesh_terms: D000328:Adult; D057205:Automation, Laboratory / Q000295:instrumentation*; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology*; D001999:Bronchoscopy; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008853:Microscopy; D008875:Middle Aged; D009169:Mycobacterium tuberculosis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013019:South Africa; D013183:Sputum / Q000382:microbiology*; D062606:Tertiary Care Centers; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*