EUH Resident Report: PCR’s sensitivity in pulmonary tuberculosis

The Bottom Line: Combining CT findings of consolidation and QFT test results may improve clinicians decision-making in patients with TB-PCR-negative BA.

Reference: Kim, CH, et al. “Predictive factors for tuberculosis in patients with a TB-PCR-negative bronchial aspirate.” Infection 41.1 (2013): 187-194.

Summary: A retrospective study was conducted on patients who had undergone a bronchoscopy because of suspected PTB. Clinical, laboratory, and computed tomography (CT) findings were investigated in PTB patients with TB-PCR-negative but positive culture BA results, and non-PTB patients with a radiographic lesion comparable to the former.

Of 250 patients screened, 31 (12 %) were diagnosed with PTB by positive culture results only. Of these 31 patients, 30 (97 %) had a lesion within one-third of the hemithorax as determined by chest radiography. In the final analysis of 30 PTB and 65 non-PTB patients with comparable radiographic lesions, a positive QuantiFERON-TB Gold In-Tube (QFT) result was independently associated with an increased risk of a positive TB culture. CT findings of consolidation were a negative predictor for PTB. Patients with a negative QFT result and consolidation had a negative predictive value of 95 % for PTB, while patients with a positive QFT result and nodular CT abnormalities without consolidation had a positive predictive value of 86 % for PTB.

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