Evaluation of ‘TBDetect’ sputum microscopy kit for improved detection of Mycobacterium tuberculosis: a multi-centric validation study

• DOI: 10.1016/j.cmi.2020.08.020
• Publication Date: 2020-08-21T15:18:04Z
• Authors: Divya Anthwal; Rakesh Kumar Gupta; Narayan Sivaramak...; Srikanth Prasad T...; Dasarathi Das; Sanghamitra Pati; Nikita Panwalkar; Prabha Desikan; Kiran Bala; Urvashi B. Singh; Manpreet Bhalla; Ritu Singhal; Ajoy Kumar Verma; Khalid Umar Khayyam; Vithal Prasad Myn...; Rohit Sarin; Sandeep Sharma; Avi Kumar Bansal; Umesh D. Gupta; Sripad A. Patil; Abhinav Goyal; Ashawant Gupta; Manjula Singh; Nalini Kant Gupta; Sagarika Haldar; Jaya Sivaswami Tyagi
• Keywords: Adult; Aged, 80 and over; Male; Microscopy; 0303 health sciences; Adolescent; Sputum; Reproducibility of Results; Mycobacterium tuberculosis; Middle Aged; 3. Good health; Young Adult; 03 medical and health sciences; Child, Preschool; Humans; Female; Child; Tuberculosis, Pulmonary; Aged

The present study aimed to evaluate the performance of the 'TBDetect' kit-based bio-safe fluorescent microscopy filter (BioFM-Filter) microscopy in comparison with direct smear microscopy and culture for the detection of pulmonary tuberculosis (TB) in a multi-centric setting in India.The TBDetect kit enables sputum concentration through filtration using the BioFM-Filter for improved and bio-safe smear microscopy. We evaluated the performance of the TBDetect kit in a six-site multi-centric validation study on sputum collected from 2086 presumptive TB patients.The combined positivity of TBDetect microscopy performed on these sputum samples was 20% (n = 417/2086) vs 16.1% of light-emitting diode fluorescence microscopy (LED-FM, n = 337/2086) and 16% of Ziehl Neelsen (ZN) smear microscopy (n = 333/2086). The increment in positivity of TBDetect over both LED-FM and ZN smears was significant (p < 0.001). The overall sensitivity of TBDetect for six sites was ~55% (202/367, 95% confidence interval (CI): 50, 60%) vs 52% (191/367, 95% CI: 47, 57%) for LED-FM (p 0.14) and 50.9% (187/367, 95% CI: 46, 56%) for ZN smear (p < 0.05), using Mycobacterium Growth Indicator Tube culture (MGIT, n = 1949, culture positive, n = 367) as the reference standard. A bio-safety evaluation at six sites confirmed efficient sputum disinfection by TBDetect; 99.95% samples (1873/1874) were sterile after 42 days of incubation. Scientists and technicians at the study sites indicated the ease of use and convenience of TBDetect microscopy during feedback.TBDetect added value to the smear microscopy test due to its improved performance, convenience and user safety. These findings indicate that equipment-free TBDetect technology has the potential to improve TB diagnosis in basic laboratory settings by leveraging on the existing nationwide network of designated microscopy centres and primary healthcare centres.