Pandiyan, A (2020) Diagnostic Yield of Bronchial Wash in a Suspected Case of Smear - Negative and Sputum -Scarce Pulmonary Tuberculosis by CBNAAT and Liquid Mycobacterial Cultures (MGIT) in Rajiv Gandhi Government General Hospital. Masters thesis, Madras Medical College, Chennai.
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Abstract
INTRODUCTION: According to WHO global tuberculosis report 2018, Worldwide, TB is one of the top 10 causes of death and the leading cause from a single infectious agent (above HIV/AIDS). False-negative results and misdiagnosis of TB suspects are common in developing nations, as most TB control programmes use Ziehl-Neelsen (ZN) smear microscopy, has poor sensitivity and Mycobacterial culture, although gold standard, takes 2-6 weeks to yield final result. Diagnostic accuracy of CBNAAT for pulmonary TB has been reported high Patients with high risk of tuberculosis with smear negative, are the most likely to be benefited from CBNAAT. The CBNAAT utilizes DNAPCR technique for detection of Mycobacterium tuberculosis and Rifampicin resistance, gives results within 2 hours. AIM OF THE STUDY: To measure the diagnostic yield of Bronchial wash CBNAAT to detect Mycobacterium tuberculosis and compare it with liquid culture (MGIT) in a suspected case of smear negative and sputum scarce pulmonary tuberculosis. OBJECTIVES: 1. To Measure the diagnostic yield of Bronchial wash CBNAAT to detect Mycobacterium tuberculosis(MTB) and rifampicin resistance and compare it with liquid mycobacterial cultures (MGIT) in a suspected case of smear negative and sputum scarce pulmonary tuberculosis 2. The diagnostic yield was defined and measured in terms of frequency and validity by calculating sensitivity, specificity, positive and negative predictive values. STUDY CENTRE: Rajiv Gandhi Government General Hospital, Chennai. DURATION OF THE STUDY: 12 months (April 2018 - March 2019). INCLUSION CRITERIA: 1. Patients with clinical suspicion of pulmonary tuberculosis including symptoms of cough with or without expectoration for >2 weeks, weight loss, haemoptysis and loss of appetite with Smear negative. 2. Patients with radiological features suggestive of pulmonary tuberculosis. EXCLUSION CRITERIA: 1. Sputum positive for pulmonary tuberculosis. 2. Patients unfit for FOB. METHODS: • Following written consent, Bronchoscopy was performed and Bronchial wash was obtained and It was sent for ZN stain and mycobacterial liquid culture, for CBNAAT to detect Mycobacterium tuberculosis(MTB) and rifampicin Sensitivity. • One part was immediately tested using CBNAAT, second part used for ZN smear microscopy and third part for MGIT BACTEC 320 liquid culture and performed on same day. CONCLUSION: Bronchial wash CBNAAT had a superior diagnostic yield (with high sensitivity and positive predictive value) to detect Mycobacterium tuberculosis and rifampicin resistance (with high sensitivity and specificity), in those cases of suspected pulmonary tuberculosis who have either smear-negative or sputumscarce disease. Bronchial wash CBNAAT has the advantages of being inexpensive, requires less manpower and gives results on the same day. Using culture as the reference standard, CBNAAT on Bronchial wash showed a high sensitivity (92.1%). Furthermore, our study confirmed the advantage of early diagnosis of sputum smear-negative and sputum-scarce PTB by CBNAAT detecting more number of cases compared to smear microscopy. The higher sensitivity is explained by the limit of detection of CBNAAT being 131 bacilli/ml compared to the limit of detection of AFB smear which is 10,000 bacilli/ml. CBNAAT showed specificity of 88.7%. This is due to the higher CBNAAT positive culture negative cases observed as false positive cases when liquid culture (MGIT) is used as a gold standard. CBNAAT amplifies DNA from dead bacilli and reports a positive while cultures are negative.
| Item Type: | Thesis (Masters) |
|---|---|
| Additional Information: | 201727001 |
| Uncontrolled Keywords: | Diagnostic Yield, Bronchial Wash, Suspected Case of Smear - Negative and Sputum -Scarce Pulmonary Tuberculosis, CBNAAT, Liquid Mycobacterial Cultures (MGIT). |
| Subjects: | MEDICAL > Tuberculosis and Respiratory Medicine |
| Depositing User: | Subramani R |
| Date Deposited: | 04 Feb 2021 15:37 |
| Last Modified: | 04 Feb 2021 15:37 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/13801 |
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