A study on rapid confirmation of pulmonary tuberculosis in smear-negative acid fast bacilli cases by using fiberoptic bronchoscopy, done through a trans oro pharyngeal spacer

Diagnostic performance of the Xpert MTB/RIF assay in BAL fluid samples from patients under clinical suspicion of pulmonary tuberculosis: a tertiary care experience in a high-tuberculosis-burden area

OBJECTIVE

To assess the diagnostic performance of the Xpert MTB/RIF assay, a rapid molecular test for tuberculosis, comparing it with that of AFB staining and culture, in BAL fluid (BALF) samples from patients with clinically suspected pulmonary tuberculosis (PTB) who are sputum smear-negative or produce sputum samples of insufficient quantity.

METHODS

This was a retrospective study of 140 cases of suspected PTB in patients who were smear-negative or produced insufficient sputum samples and were evaluated at a tertiary teaching hospital in the city of Rio de Janeiro, Brazil. All of the patients underwent fiberoptic bronchoscopy with BAL. The BALF specimens were evaluated by AFB staining, mycobacterial culture, and the Xpert MTB/RIF assay.

RESULTS

Among the 140 patients, results for all three microbiological examinations were available for 73 (52.1%), of whom 22 tested positive on culture, 17 tested positive on AFB staining, and 20 tested positive on the Xpert MTB/RIF assay. The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy for AFB staining were 68.1%, 96.1%, 88.2%, 87.5%, and 87.6%, respectively, compared with 81.8%, 96.1%, 90.0%, 92.4%, and 91.8%, respectively, for the Xpert MTB/RIF assay. The agreement between AFB staining and culture was 82.3% (kappa = 0.46; p < 0.0001), whereas that between the Xpert MTB/RIF assay and culture was 91.8% (kappa = 0.8; p < 0.0001).

CONCLUSIONS

In BALF samples, the Xpert MTB/RIF assay performs better than do traditional methods, providing a reliable alternative to sputum analysis in suspected cases of PTB. However, the rate of discordant results merits careful consideration.

The Value of Bronchoalveolar Lavage in the Diagnosis of Sputum Smear-NegativePulmonary Tuberculosis

BACKGROUND AND OBJECTIVES

Sputum smear staining for acid-fast bacilli is initial approach to the diagnosis of pulmonary tuberculosis (PTB) but more than 50% of cases are sputum smear-negative. This study was aimed to investigate the diagnostic value of fiberoptic bronchoscopy (FOB) guided bronchoalveolar lavage (BAL) in patients suspected to have tuberculosis.

METHODS

This prospective cross-sectional study was carried out on 290 sputum smear-negative patients who were clinically suspicious for PTB in 2006-12. All patients were subjected to FOB andBAL, then BAL specimens stained and cultured.

RESULTS

Of the 290 patients, 173 cases (59.7%) were men and 117 cases (40.3%) were women with the age of 52.6±19.1 years (ranged 20-76 years). Of the total 290 BAL specimens, 110 specimens (38%) were positive for acid-fast bacilli. Sensitivity, specificity, PPV and NPV was 60%, 91%, 89% and 64%, respectively. Also, LR (+) and LR (-) was 64.6% and 0.44%, respectively.

CONCLUSION

FOB guided BAL is a reliable, rapid and useful method for establishing the diagnosis of smear negative PTB with minimal complications.