The utility of polymerase chain reaction in the diagnosis of pulmonary tuberculosis in smear-negative, culture-negative patients

Abstract EN

Objective: This study was conducted to assess the use of polymerase chain reaction (PCR) amplification in diagnosing pulmonary tuberculosis (PTB) in smear-negative, culture negative (SNCN) patients.

Method: Fourteen patients with suspected PTB and SNCN status were identified.

All of them underwent bronchoscopy to obtain bronchoalveolar lavage (BAL).

All BAL's were examined with aura mine stain for acid fast bacilli (AFB), mycobacterium culture and PCR to detect mycobacterium tuberculosis (MTB).

All patients were prospectively followed-up to assess response to therapy and final outcome.

Result: Seven patients had positive results with PCR.

Follow-up showed that in six of these patients PTB was the most likely diagnosis while one (14.3%) out of seven was considered as false-positive.

The remaining seven patients had negative results with PCR.

These were considered as true-negative as their clinical course did not support the diagnosis of PTB.

Conclusion: PCR test in BAL to detect MTB is a useful test in suspected cases of PTB with SNCN results.

However, the final interpretation of this test should always be subjected to the clinical course of the patient because of the recorded rate of false-positive results in such group.