A Bundled Approach to Pulmonary Tuberculosis Testing: Experience from a Tertiary Care Centre in South India

The diagnosis of pulmonary tuberculosis (PTB) is based on a stepwise approach consisting of sputum microscopy and molecular testing (GeneXpert), with the use of Mycobacterium culture in select cases. We analysed a bundled approach of PTB testing, consisting of all three of these tests during the patient's first visit, for all patients fitting into the clinical criteria of PTB. We retrospectively analysed the medical records of all patients who underwent the TB diagnosis bundle during a period of 29 months. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of sputum microscopy and GeneXpert were compared against the gold standard of Mycobacterium culture. The incremental yield of diagnosing PTB by addition of Mycobacterium culture in the diagnostic bundle during the initial testing was also calculated. The bundled approach conferred an advantage in terms of faster clinical decision and increased diagnosis rates, by virtue of the speed of smear microscopy and GeneXpert, combined with the higher sensitivity of culture. The bundle also had the additional benefit of detecting non-tuberculous Mycobacterium (NTM) by the culture method. Hence we feel that the bundled approach ensures fewer number of hospital visits and reduces the potential delays in a clinical decision making.