Diagnosis Of Sputum Smear-negative Pulmonary Tuberculosis Research Articles

Diagnostic Role of Serum Adenosine Deaminase In Smear-negative Pulmonary Tuberculosis

Background: Diagnosis of tuberculosis is not always easy, particularly if it is a case of sputum smear-negative pulmonary tuberculosis (SNPTB). Patients with respiratory symptoms resembling SNPTB are difficult to differentiate based on clinical features, chest X-ray, and Xpert MTB/RIF negativity. So, additional diagnostic test with high sensitivity and specificity is needed to increase the yield of the ongoing diagnostic strategy for SNPTB. Adenosine deaminase (ADA) is now being widely used for the diagnosis of TB particularly in effusion fluids due to its simplicity, low cost, and quick available results, it is not always possible to access effusion fluids and therefore, it would be helpful to take advantage of serum levels. Therefore, the purpose of the study was to assess the role of serum ADA in the diagnosis of SNPTB. Methods: This cross-sectional analytical study was conducted in Dhaka Medical College & Hospital, Dhaka from March 2019 to September 2021. A total of 140 patients were included in this study and divided into two groups according to selection criteria: Group I (SNPTB, n=62), and Group II (non-TB pulmonary diseases, n=78). ADA estimation was carried out using the sensitive colorimetric method described by Guisti and Galanti with a BIOSIC kit. After the collection of all the required data, analysis was done by SPSS 24.0. Results: The mean age of the study patients was 48.02 ± 9.60 years (23-73 years) with male predominance in both Group I and Group II (71 % and 60.3%, respectively, p>0.05). Non-TB pulmonary cases were significantly older than SNPTBpatients (52 ± 8.56 vs 43.02 ± 8.49 years, p<0.001). SNPTB patients had a significantly higher frequency of cough, fever, and weight loss compared to non-TB pulmonary cases (p<0.05). In contrast, chest pain and shortness of breath were more frequent in Group II than in Group I (p<0.05). Serum ADA was significantly higher among SNPTB patients compared to non-TB pulmonary cases (48.16 ± 12.13 vs 18.64 ± 7.85 IU/L, p<0.001). ROC analysis of serum ADA in the diagnosis of patients with SNPTB found an AUC of 0.9850 (95% CI, 0.969-1.00) which was statistically significant (p<0.001). A cut-off value of serum ADAe”33 IU/L showed sensitivity, specificity, NPV, PPV, and accuracy of 93.55%, 94.87%, 94.87%, 93.55%, and 94.29%, respectively to correctly diagnose SNPTB cases. Conclusion. This study finding stated that serum ADA may be a useful marker to distinguish SNPTB from non-TB respiratory diseases. However, further study with a more generalized study population is recommended. Bangladesh J Medicine 2024; 35: 61-69

Role of bronchoalveolar lavage cartridge-based nuclear acid amplification test in the diagnosis of sputum smear-negative pulmonary tuberculosis

Background Approximately 40–60% of clinical and radiological suspected cases of pulmonary tuberculosis (PTB) will have sputum smear result negative for acid-fast bacilli (AFB). Establishing early diagnosis and starting treatment early can have significant effect on morbidity and mortality in these patients. Bronchoalveolar lavage (BAL) samples obtained by bronchoscopy can be tested with cartridge-based nuclear acid amplification test (CBNAAT) for rapid diagnosis of sputum smear-negative PTB cases. Objectives To assess the role of BAL CBNAAT in the early diagnosis of sputum smear-negative PTB cases. Patients and methods A total of 112 patients with clinicoradiological findings suggestive of PTB with two consecutive sputum smear-negative results for AFB were enrolled in the study. BAL samples were subjected to Ziehl–Neelsen staining, CBNAAT (Xpert MTB/Rif; Cepheid), and liquid culture by mycobacteria growth indicator tube method as standard reference. Sputum samples from the same patients were also cultured. Results BAL samples were positive for AFB on Ziehl–Neelsen staining in 64.2% of smear-negative patients. CBNAAT was positive in 75.8%, whereas mycobacteria growth indicator tube was positive in 76.7% as compared with sputum culture positivity, which was positive in 19.6% of patients. Sensitivity and specificity of CBNAAT were 96.51 and 86.3%, respectively, when compared with culture results. Overall, 76.7% of patients were diagnosed as having culture-positive PTB. Conclusion BAL CBNAAT is useful in the early diagnosis of sputum smear-negative PTB, thus reducing the morbidity and mortality among these patients.