Pcr for Tb Pleural Effusion

Between October 1998 and September 1999, 98 patients with symptomatic exudative lymphocytic pleural effusion were enrolled in our study to evaluated the diagnostic sensitivity of polymerase chain reaction (PCR) assay. The mean age was 53.3 years ranging from 18 to 78 years. There were 61 men and 37 women. Pleural fluid was sent for gram staining, AFB staining, aerobic culture, culture of Mycobacterium tuberculosis on LJ media, and cytology. Additional fluid was used for a PCR-assay of the 16 S 23 S rRNA gene spacer sequences and for a nested PCR of the 16 S rRNA gene as a blind control. In cases of free-flow pleural tapping, histopathological analysis was done on three pleural biopsies. Overall etiologies comprised malignancy 53.1%, tuberculosis 36.7%, lymphoma 2.0% and chronic nonspecific inflammation 8.2%. The sensitivity and specificity of AFB-staining were 6% and 79%, respectively; while cultures on LJ media were 17% and 100%, respectively. The sensitivity of the PCR-assay was 50% (95% CI : 40 to 60%) and the specificity was 61% (95 CI : 52 to 71%). When PCR was nested, the sensitivity was 72% (95% CI : 63 to 81%) and specificity was 53% (95% CI : 43 to 63%). Two thirds (26 of 36) of tuberculous pleural effusion cases underwent pleural biopsy, and 62% were diagnosed by histopathology. There were no complications from thoracocentesis or pleural biopsy in any of the patients. We concluded that PCR assay was more sensitive than AFB staining and mycobacteria culture for diagnosis tuberculous pleural effusion but its specificity was quite low. SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH Vol 31 No. 3 September 2000 510 with exudative lymphocytic pleural effusion were diagnosed according to Light’s criteria (Heffner et al, 1997) and then enrolled in our study. Patients with bleeding tendency were excluded. Pleural fluid was sent for conventional diagnosis including gram staining, AFB staining, aerobic culture, culture for M. tuberculosis on LowensteinJensen (LJ)media, and cytology. Additional pleural fluid was used for PCR-assay in a control laboratory; the assessors were not informed of the clinical diagnosis of each patient. For histopathology, three pieces of pleural biopsy using a Abram’s needle were taken where free-flow pleural tapping was possible. Tuberculous pleural effusion was diagnosed if: 1) the M. tuberculosis culture was positive, 2) the pleural pathology showed caseating granuloma in the absence of other pleural granulomatous diseases, or 3) the clinical symptoms or chest radiograph responded to antituberculous drugs.