Original Research Article
Year: 2020 | Month: February | Volume: 7 | Issue: 2 | Pages: 261-267
A Prospective Study for Evaluation of Diagnostic Utility of Gene XPERT MTB/RIF Assay in Tuberculous Pleural Effusion
Laxman Babu. V1, M. Archana2, Gourav Shah3, Shiva Kumar. B4
1MD, Consultant Pulmonologist, Department of Pulmonology, Yashoda Super Speciality Hospital, Hyderabad.
2MD, Assistant Professor, Department of Microbiology,Government Medical College, Nalgonda, Telangana - 500003
3DNB General Medicine, Department of Medicine, Yashoda Super Speciality Hospital, Hyderabad.
4Clinical research Department, Sunshine Hospital, Hyderabad.
Corresponding Author: M. Archana
ABSTRACT
Aim: The aim of the present study is to evaluate the diagnostic usefulness of Gene Xpert MTB/RIF assay in quick diagnosis of pleural tuberculosis, comparing it with conventional methods like pleural fluid Culture and AFB smear, histopathology of pleural biopsy tissue and determination of adenosine deaminase (ADA) in pleural fluid with lymphocytic predominance which counter to anti tubercular treatment.
Methods: This is a prospective observational study, done over a period of two years (Jan 2015 to Dec 2016) at Yashoda Super speciality Hospital, Hyderabad. After scientific and ethical committee approval, and after informed consent, the patients included were those with exudative pleural effusion and showing positive evidence in favor of pleural tuberculosis by any of these techniques (i) Pleural fluid microscopy / culture (or) (ii) Pleural biopsy and evidence of caseous necrosis / granuloma, (or) (iii) Pleural fluid ADA levels > 50 U/ml with lymphocytic predominance and response to anti tubercular treatment. And will be followed over for 3 months.
Results: In this study, the mean age of individuals is 42 years, the maximum was 85 years and minimum was 15 years. Highest numbers were among age group of 21-30 and 51-60 years, the gender distribution was approximately 2.3:1, among which 69 % were males and 31% females. The prominent symptoms were Cough (91%) with or without expectoration, fever (80%), dyspnoea (56%), anorexia and weight loss (50%), chest pain (18%), hemoptysis (3%). ZN staining was positive for Acid Fast bacilli in 4 cases (6%). Culture was not positive in any case. Histopathological examination of pleural biopsy revealed granuloma / caseous necrosis in 12 of 14 cases (85%). Gene Xpert was analysed in all cases and was positive in 12 cases of 54 patients in pleural fluid (22%) and 8 cases of 14 biopsy was positive (57%). It has specificity of 100% and Positive predictive value and negative predictive value of 100% and 68.6% respectively.
Conclusions: ADA with lymphocytosis in exudative pleural fluid remains useful diagnostic tool in clinical practice and histopathological examination of pleural tissue is useful in few uncertain cases. The yield of AFB smear and Culture is very low, making them less reliable test for accurate diagnosis. The Gene Xpert MTB/RIF assay has better yield in pleural biopsy samples compared to that in pleural fluid samples. Gene Xpert MTB/RIF assay is simple, quick and needs minimal technical expertise, but has low sensitivity but has a limited diagnostic capacity for pleural fluid samples of TB origin, which precludes its widespread implementation in this setting.
Keywords: Pleural tuberculosis; granuloma; adenosine deaminase.
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