Real-time polymerase chain reaction in bronchial aspirate for rapid detection of sputum smear-negative tuberculosis.

SETTING

The real-time polymerase chain reaction (RT-PCR) has increasingly been used for the detection of various micro-organisms, including mycobacteria.

OBJECTIVE

To determine the role of RT-PCR in confirming the diagnosis of tuberculosis (TB) when acid-fast bacilli (AFB) smear results in sputum samples were not available (i.e., no sputum or negative smear results).

DESIGN

We analysed the data of consecutive patients whose bronchial aspirate (BA) was tested for RT-PCR for the diagnosis of TB from January 2006 to April 2008. Computed tomography (CT), bronchoscopy and tissue biopsies were performed in all patients for confirmatory diagnosis, and BA was collected for microbiological analyses and RT-PCR. Final diagnoses were based on microbiological or clinicopathological criteria.

RESULTS

Final diagnoses were made in 136 patients, and TB was confirmed in 77 (including 65 culture-positive patients). RT-PCR was positive in 51.9% (40/77) of the confirmed TB patients. More TB patients (20.8%) were detected using RT-PCR than using BA-AFB stain (40 vs. 20, P < 0.001). Of the 77 TB patients, 44 (57.1%) were detected within a few days using a combination of BA-AFB and RT-PCR.

CONCLUSION

Real-time RT-PCR of bronchial aspirate seems to be useful for the rapid diagnosis of TB in suspects with smear-negative TB sputum or no sputum.