Fibreoptic bronchoscopy in the diagnosis of sputum smear-negative pulmonary tuberculosis: current status

Sputum smear-negative pulmonary tuberculosis (SSN-PTB) is a common problem faced by clinicians. Performing fibreoptic bronchoscopy (FOB), and subjecting the bronchoscopic secretions/transbronchial lung biopsy (TBLB) material to conventional diagnostic methods of smear, mycobacterial culture and histopathology appears to be helpful in the diagnosis of SSN-PTB. Application of polymerase chain reaction (PCR) may be helpful as an adjunctive method in the appropriate clinical setting. The FOB facilitates rapid diagnosis and offers the additional advantage of the diagnosis of several conditions that may mimic PTB. However, FOB is an invasive procedure, and is associated with the risk of transmission of tuberculosis (TB) and other infections. It is costly, and is not widely available in the developing countries. In developed countries with no limitations on resources, early FOB seems to be the best course of action in a patient with suspected SSN-PTB. In resource-poor settings, where transmission of TB is high, sputum induction with hypertonic saline can be useful in adding to the diagnostic yield. If the TB suspect still remains induced sputum smear-negative, and if the pre-test probability of the patient having PTB is high, starting antituberculosis treatment (ATT) and closely monitoring the patient and reserving FOB to those patients who do not seem to improve/deteriorate or those who have a negative spontaneously expectorated/induced sputum culture (if performed and available) seems to be a practically useful approach. Proper precautions must be followed to disinfect the bronchoscope in between use so as to minimise the risk of nosocomial transmission of infection.