Diagnosis of Pleural Tuberculosis with Negative Cultures

Diagnostic Approach

The American Thoracic Society recommends that pleural fluid cultures for tuberculosis have a limited sensitivity of 23-58%, resulting in frequent false-negative results 1, 2
Despite the high specificity of culture (>97%), a negative result does not rule out pleural tuberculosis due to the paucibacillary nature of this form of extrapulmonary tuberculosis 2
The British Thoracic Society strongly recommends pleural biopsy as the preferred option for all patients with suspected tuberculous pleural effusion (strong recommendation) 3, 4
Histological examination of pleural tissue has a sensitivity of 69-97% for the diagnosis of pleural tuberculosis 5, 6

In populations with high prevalence of tuberculosis, adenosine deaminase (ADA) and/or interferon-gamma (IFN-gamma) in pleural fluid may be considered for diagnosing tuberculous pleural effusion 3, 4
In populations with low prevalence, ADA in pleural fluid may be considered as a test to rule out pleural tuberculosis 3, 4
Nucleic acid amplification testing (NAAT) has a sensitivity of 56% in pleural fluid, but high specificity of 98%, making a positive result useful but a negative result not ruling out the disease 5

When suspecting pleural tuberculosis, thoracocentesis should be performed for pleural fluid analysis, and samples should be sent for smear microscopy, culture, and ADA 3, 4, 2, 7
If initial results are negative or inconclusive, image-guided or thoracoscopic pleural biopsy should be performed, and tissue should be sent for histology, culture, and molecular tests 3, 4, 5, 6
A positive culture confirms the diagnosis (high specificity >97%), and compatible histological findings (granulomas) are highly suggestive 1, 2, 5, 6