Smear negative pulmonary tuberculosis and infectivity

Pulmonary tuberculosis is a major health problem in Bangladesh that is responsible for about 7% of total death in a year. This study was conducted to isolate and identify Mycobacterium tuberculosis from sputum and to evaluate the efficacy of PCR as a modern diagnostic tool, for diagnosis of pulmonary tuberculosis, especially in the smear negative cases. One hundred and fifty suspected pulmonary TB patients (male/ female: 97/53) were included in this study. Single morning sputum was collected from each patient and diagnostic potential of PCR was compared with staining and culture. Twenty five (16.7%) sputum were positive by ZN stained smear. Among 125 smear negative samples, 13 (10.4%) yielded growth in culture in LJ media and 21 (16.8%) samples were positive by PCR. The sensitivity and specificity of PCR in smear negative cases was 100% and 92.9% respectively. Mean detection time in PCR was 24 hours. PCR detected M. tuberculosis in 21 smear negative and 9 culture negative samples. For diagnosis of tuberculosis in smear negative cases, PCR directly from sputum was a very sensitive and accurate method. In conclusion, PCR may be done, especially in clinically suspected pulmonary tuberculosis patients who remain negative by conventional methods.DOI: http://dx.doi.org/10.3329/bjmm.v6i2.19368 Bangladesh J Med Microbiol 2012; 06(02): 2-6

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Role of fibreoptic bronchoscopy in sputum smear negative pulmonary tuberculosis

Tubercle and Lung Disease ◽

10.1016/0962-8479(94)90786-2 ◽

1994 ◽

Vol 75 ◽

pp. 29

Author(s):

A. McDaniel ◽

N. Schoenfeld ◽

W. Frank ◽

A. Grassot ◽

H. Mauch ◽

...

Keyword(s):

Pulmonary Tuberculosis ◽

Fibreoptic Bronchoscopy ◽

Sputum Smear ◽

Smear Negative

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Evaluation of the performance of clinical predictors in estimating the probability of pulmonary tuberculosis among smear-negative cases in Northern Ethiopia: a cross-sectional study

BMJ Open ◽

10.1136/bmjopen-2020-037913 ◽

2020 ◽

Vol 10 (11) ◽

pp. e037913

Author(s):

Mala George ◽

Geert-Jan Dinant ◽

Efrem Kentiba ◽

Teklu Teshome ◽

Abinet Teshome ◽

...

Keyword(s):

Pulmonary Tuberculosis ◽

Cross Sectional Study ◽

Clinical Suspicion ◽

Secondary Outcome ◽

Northern Ethiopia ◽

Sectional Study ◽

Cross Sectional ◽

Smear Negative ◽

Culture Positive ◽

Culture Negative

ObjectivesTo evaluate the performance of the predictors in estimating the probability of pulmonary tuberculosis (PTB) when all versus only significant variables are combined into a decision model (1) among all clinical suspects and (2) among smear-negative cases based on the results of culture tests.DesignA cross-sectional study.SettingTwo public referral hospitals in Tigray, Ethiopia.ParticipantsA total of 426 consecutive adult patients admitted to the hospitals with clinical suspicion of PTB were screened by sputum smear microscopy and chest radiograph (chest X-ray (CXR)) in accordance with the Ethiopian guidelines of the National Tuberculosis and Leprosy Program. Discontinuation of antituberculosis therapy in the past 3 months, unproductive cough, HIV positivity and unwillingness to give written informed consent were the basis of exclusion from the study.Primary and secondary outcome measuresA total of 354 patients were included in the final analysis, while 72 patients were excluded because culture tests were not done.ResultsThe strongest predictive variables of culture-positive PTB among patients with clinical suspicion were a positive smear test (OR 172; 95% CI 23.23 to 1273.54) and having CXR lesions compatible with PTB (OR 10.401; 95% CI 5.862 to 18.454). The regression model had a good predictive performance for identifying culture-positive PTB among patients with clinical suspicion (area under the curve (AUC) 0.84), but it was rather poor in patients with a negative smear result (AUC 0.64). Combining all the predictors in the model compared with only the independent significant variables did not really improve its performance to identify culture-positive (AUC 0.84–0.87) and culture-negative (AUC 0.64–0.69) PTB.ConclusionsOur finding suggests that predictive models based on clinical variables will not be useful to discriminate patients with culture-negative PTB from patients with culture-positive PTB among patients with smear-negative cases.

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