Evaluating diagnostic performance of Truenat MTB Plus for gastrointestinal tuberculosis

Abstract

Background and Aim Prompt and accurate diagnosis of gastrointestinal tuberculosis (GITB) along with simultaneous detection of drug resistance is inevitable for tuberculosis elimination. Truenat MTB Plus (TruPlus), a chip‐based real‐time polymerase chain reaction assay, was evaluated for the first time for diagnosing GITB and detecting rifampicin resistance. Methods Fifty ileocecal biopsy specimens (5 microbiologically confirmed GITB [culture‐positive], 25 clinically confirmed GITB [culture‐negative], and 20 control patients) processed in the Department of Microbiology between 2011 and 2021 were subjected to TruPlus assay, Xpert MTB RIF assay multiplex polymerase chain reaction. Their performance was evaluated against both culture and composite reference standard. Results The overall sensitivity and specificity of TruPlus in diagnosing GITB was 70% (21/30) and 100%, respectively. The sensitivity was 60% (3/5) for microbiologically confirmed cases and 72% (18/25) for clinically confirmed cases. Performance of TruPlus was superior to Xpert (sensitivity = 30%; P = 0.001) and comparable with MPCR (sensitivity = 83.33%; P = 0.13). Both TruPlus and MPCR had moderate agreement with reference standards, and MPCR detected additional three cases. Both TruPlus and Xpert correctly reported Rifampicin resistance in three cases. Conclusions TruPlus, with its greater portability and higher sensitivity than Xpert, could serve as an important tool for diagnosing GITB and rifampicin resistance at outreach endemic areas.

MTBDRplus and MTBDRsl for simultaneous diagnosis of gastrointestinal tuberculosis and detection of first‐line and second‐line drug resistance

“…The NAATs provide an opportunity for reliable diagnosis of GITB by amplification and detection of DNA of M. tuberculosis . The ileocecal biopsy was used as the sample in the current study as this site is involved in 64% of GITB cases 20 and has reported highest bacillary yield in previous studies, 14 because of lymphoid aggregates, minimal activity, and neutralized digestive secretions 21 . MTBDRplus and MTBDRsl assays, with their ability to detect both first‐line and second‐line drug resistance simultaneously, could serve as beacons of hope for TB elimination 2,22 .…”

“…Overcoming the limitations of conventional microbiological tests, a variety of nucleic acid amplification tests (NAATs) have been used for diagnosing GITB (multiplex polymerase chain reaction, 12 loop‐mediated isothermal assay, 13 etc.) and also for detecting DR‐GITB (GeneXpert and Truenat) 14 . While GeneXpert is limited to detection of Rif resistance only, Truenat allows detection of MDR, pre‐XDR, and XDR, albeit using separate amplification chips for each.…”

Evidence-based approach to diagnosis and management of abdominal tuberculosis

“…No reports are available on the utility of newer PCR-based diagnostics such as Xpert Ultra. One study has reported that the sensitivity and specificity of Truenat MTB Plus (TruPlus) were 70% and 100%, respectively [58]. As with peritoneal tuberculosis, multiplex PCR based on multiple probes has been found to be sensitive and specific but needs validation [52,58].…”

Assessing the utility of Truenat in extrapulmonary tuberculosis diagnosis – A NRL’s experience

“…However, there is limited data on the Truenat’s utility in diagnosing EPTB especially from India. Studies from Chandigarh documented a sensitivity of 66.6% and 70% in Truenat testing of vitreous fluid and ileocecal biopsy specimens respectively [6] , [7] . A study from Kerala that tested different extrapulmonary specimens demonstrated 100% sensitivity of Truenat testing for M.tuberculosis diagnosis [8] .…”