Abstract
BackgroundIn most developing countries, smear-negative pulmonary TB (SNPT) often gets missed from the diagnosis of consideration, though it accounts 30–65% of total PTB cases, due to deficient or inaccessible molecular diagnostic modalities.MethodsThe cross-sectional study enrolled 360 patients with clinical-radiological suspicion of SNPT in Tribhuvan University Teaching Hospital (TUTH). The patient selection was done as per the algorithm of Nepal’s National Tuberculosis Program (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 the Ziehl-Neelsen technique then observed microscopically. Both findings were interpreted; rifampicin-resistant, if obtained, on Xpert testing was confirmed with a Line Probe Assay.ResultOf 360 smear-negative sputum samples analyzed, 85(23.61%) found positive while 3(0.8%) of them were rifampicin resistance. The infection was higher in males, 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, the additional case 16.5% (n = 85/515) from smear-negative presumptive TB cases were detected. Among the most occurring clinical presentations, cough and chest pain were positively associated with SNPT. While upper lobe infiltrates (36.4%) and pleural effusion (40.4%) were the most peculiar radiological impression noted in PTB patient. 94 multi-drug resistant(MDR) suspected cases were enrolled; of total suspects, 29(30.8%) samples were rifampicin sensitive, 1(1.06%) indeterminate, 3(3.19%) rifampicin-resistant while remaining of them were negative. 2(2.2%) MDR cases were recovered from the patient with a previous history of ATT, of total 89 previously treated cases enrolled However, a single rifampicin-resistant from the new suspects.ConclusionWith an application of the assay, the additional cases, missed with smear microscopy, could be sought and exact incidence of the diseases could be revealed.
Highlights
In most developing countries, smear-negative pulmonary TB (SNPT) often gets missed from the diagnosis of consideration, though it accounts 30–65% of total PTB cases, due to deficient or inaccessible molecular diagnostic modalities
In most developing countries due to deficient or inaccessible molecular diagnostic modalities, SNPT often gets missed from the diagnosis of consideration—though it accounts for 30–65% of total PTB cases [6, 7]
Before the introduction of Gene Xpert, the laboratory setting of this hospital was limited with AFB smear microscopy and Mycobacterium tuberculosis (MTB) culture but no drug susceptibility test (DST) facility
Summary
Smear-negative pulmonary TB (SNPT) often gets missed from the diagnosis of consideration, though it accounts 30–65% of total PTB cases, due to deficient or inaccessible molecular diagnostic modalities. Tuberculosis is a treatable and curable disease (if early diagnosis of etiology and its drug resistance status could be made) but has been existing as a major public-health-threat around the globe [1]. The reasons behind this unyielding infection are due to inaccessible or lacking diagnostic tool which carries higher precision and over-relying on clinical presentations, chest radiography and/or sputum smear microscopy—in most health centers of developing countries [2,3,4]. Billions of dollars are being spent in developed nations; is worthless and these nations could not skip alone from the infection. Developing nations should be boosted continously with the collaborative support (financial and technological support) from developed nations
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