ABSTRACT
Tuberculosis is one of the major health problems in developing countries like India. Even though lungs are the commonly involved organs in Tuberculosis, extrapulmonary presentations are on the rise nowadays. Among the various types of presentations of extrapulmonary tuberculosis, lymphadenitis is the most common presentation. A spectrum of investigations is available for diagnosis, and molecular methods like CBNAAT and PCR analysis are highly reliable. But their disadvantage is their cost and requirement of trained personnel. FNA is the first line of investigation but is lacking in sensitivity and culture method is time consuming. So, Modified Ziehl Neelsen method with low cost and less time may be considered as an alternative. We wanted to evaluate the sensitivity of the Modified Bleach Ziehl Neelsen method and compare the Modified and Conventional Ziehl Neelsen Method in association with the CBNAAT in the diagnosis of TB lymphadenitis.METHODSDiagnostic validation study was conducted with 30 clinically suspected cases of tuberculosis. FNA was done and aspirated material was spread on 2 slides. Slides were stained with H & E stain and convention Ziehl Neelsen stain. Part of the aspirate material was centrifuged with 5 % sodium hypochlorite. Sediment was smeared on a slide and stained with Ziehl Neelsen stain. Remaining material was subjected to CBNAAT assay.RESULTSCorrelation shows that 9, 6, and 11 out of 30 cases were positive for tuberculosis in Conventional, Modified and CBNAAT methods respectively. Sensitivity was 81.81 %; specificity was 94.74%, positive predictive value was 90% and negative predictive value was 90% for Conventional Ziehl Neelsen Method and 54.55%, 94.73%, 85.71% and 78.26%, respectively for modified bleach method.CONCLUSIONSConventional method is found to be more sensitive than modified method. CBNAAT negative results do not rule out TB. So, they should be correlated with cytology and microbiological studies.
ABSTRACT
Background: Tuberculosis is one of the most common opportunistic infections among people with HIV infection. Detection of pulmonary tuberculosis by sputum-based techniques includes microscopy and culture. However, in people living with HIV, sputum production is scanty and also the sputum contains less number of bacilli due to fewer cavitations, thereby decreasing the sensitivity and specificity of sputum microscopy as a diagnostic tool. Aim of the study: In this study, we assess the usefulness of CBNAAT in the early detection of pulmonary tuberculosis and its incidence by using CBNAAT in smear-negative HIV patients using mycobacterial culture in Lowenstein Jensen medium as Gold Standard. Materials and methods: The study was conducted in the Department of Cardiothoracic Surgery, Government Mohan Kumaramangalam Medical College Hospital. Data were collected from 150 HIV infected patients who tested sputum smear negative. Sputum samples were then sent for CBNAAT and sputum culture for mycobacteria. Results: Of the 150 patients enrolled, 28(18.66%) of them were detected with MTB by CBNAAT; whereas sputum culture could detect 38(25.33%) of them. Thus, compared to sputum smear, CBNAAT increases TB detection by 18.66% and sputum culture increases by 25.33%. The sensitivity of CBNAAT in our study was 73.68% and the incidence of smear-negative pulmonary TB in the study population by using CBNAAT was 18.66%. Conclusion: CBNAAT is a highly sensitive and diagnostic stool for the diagnosis of pulmonary TB and it is of immense help in the early diagnosis of smear-negative pulmonary TB in HIV infected patients. Therefore, CBNAAT should be used as the initial test in HIV infected patients suspected with pulmonary TB.