Abstract
Background
For improving patient care and abbreviating the disease transmission chain, speedy detection of tuberculosis and its drug-resistance with precision is crucial.
Methods
We analyzed, pulmonary tuberculosis (PTB) suspected, 360 smear-negative sputum from the patients attending Tribhuvan University Teaching Hospital (TUTH). The patients were selected as per the algorithm of National Tuberculosis Programme(NTP) for Xpert MTB/RIF testing. Participants’ demographic and clinical information were collected using a pre-tested questionnaire. The specimens were collected, processed directly for Xpert MTB/RIF test according to the manufacturer’s protocol. The same samples were stained using Ziehl-Neelsen technique then observed microscopically. Both findings were interpreted; rifampicin-resistant, if obtained, on Xpert testing was confirmed with Line Probe Assay.
Result
Of 360 smear-negative sputum samples analyzed, 85(23.61%) found positive while 3 of them were rifampicin resistance. The infection was higher in male, i.e. 60(25.3%) compared to female 25(20.3%). The age group, >45(nearly 33%) with median age 42± 21.5, were prone to the infection. During the study period, 4.6% (515/11048) sputum samples were reported as smear-positive in TUTH; consequently, with Xpert MTB/RIF assay, additional case 16.5% (n=85/515) missed on the smear microscopy, were detected—surging overall confirmed cases. Among the most occurring clinical presentations, cough and chest pain were more evident in PTB with relative-risk at 95% confident-levels i.e. 3.03(1.01-9.11) and 3.47(2.29-5.27) respectively. A higher number of new suspects (n=63) were found positive compared to previously treated suspects. The upper lobe infiltrates (36.4%) and pleural effusion (40.4%) were peculiar radiological impression noted in PTB patient. 94 MDR suspected cases were enrolled; of total suspected cases, 29 samples were found rifampicin sensitive, 1 indeterminant while 2 of them were rifampicin-resistant. However, a single rifampicin-resistant; case was detected in patient which was not MDR suspected.
Conclusion
Additional cases of PTB which are neglected as smear-negative on microscopy and other conventional tests can be detected with gene Xpert test. Hence, recommended to every suspect as a presumptive test could be a wise investment in diagnosis to restrict the global burden to some extent.
Keywords: Xpert MTB/Rif assay, Mycobacterium tuberculosis, Line Probe Assay, MDR-TB
Diagnostic performance of genoType® MTBDRplus line probe assay in bronchoalveolar lavage for pulmonary tuberculosis diagnosis in sputum scarce and smear-negative patients
