CBNAAT Co-Testing of Sputum and BAL Fluid with Sputum Microscopy: May it Halt the March of Tuberculosis

Introduction: Growing concern for Tuberculosis (TB) epidemic forces World Health Organization (WHO) and government of India (GOI) to incorporate newer rapid and highly specific diagnostic test like Cartridge Based Nucleic Acid Amplification Test (CBNAAT). Aim: To find the usefulness of CBNAAT in increasing Acid Fast Bacilli (AFB) positive patient pool over and above the yield of traditional sputum microscopy. Materials and Methods: The cross-sectional survey was conducted in the Department of Respiratory Medicine, Nilratan Sircar Medical College and Hospital (NRSMCH), Kolkata, India. The study involved 94 smear negative TB suspects referred from other health facilities as well as diagnosed by the department itself. After collecting baseline information like age, sex, previous history of TB and its treatment by interview and scrutinizing records using predesigned questionnaire, the patients were put on sputum CBNAAT and Broncho-Alveolar Lavage (BAL)- CBNAAT testing. Data were analysed by estimating mean, Standard Deviation (SD), proportion and using independent t-test, chi-square test. Results: Overall, average age of participants was 44.7±15.3 (mean±SD) years. Male-female ratio was 1:2.8. Altogether 44.7% patients were detected sputum positive out of which 34.0% were detected only by sputum CBNAAT and another 10.7% detected when BAL-CBNAAT testing was used among the negatives yielded from sputum CBNAAT only. These differences were statistically significant. Conclusion: Utility of CBNAAT over and above traditional diagnostic methods was reaffirmed. With added advantage of detecting MDR cases simple, sensitive, speedy and automated CBNAAT seems new mile stone in ‘Stop TB’ strategy and needs utilised to its highest potentiality through monitoring and supervision.