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Bronchial Aspirates in the Diagnosis of Pulmonary Tuberculosis: AFB

In AFB smear-negative patients, the sensitivity, specificity, PPV, and NPV of CA tests were 38%, 99%, 74%, and 94%, respectively. Overall, the sensitivity, specificity, PPV, and NPV of CA tests were 53%, 98%, 81%, and 94%, respectively. In nine patients with clinical tuberculosis, one patient had a positive finding in both AFB smear and CA tests, two patients had positive findings only in CA tests, and six patients had negative findings in both AFB smear and CA tests.
With regard to the washing order of the bronchoscopes, there were three episodes of possible contamination via bronchoscope washer. However, of three events of possible contamination, two had truly confirmed tuberculosis; one was confirmed by histologic diagnosis, and the other had a positive culture for M tuberculosis in another sputum examination this canadian neighbor pharmacy. The remaining patient (Fig 1, C) had lung cancer and no evidence of tuberculosis clinically or bacteriologically, so a contamination via bronchoscope washer could be suspected. The patient who underwent bronchoscopy using the same bronchoscope immediately before patient C had no evidence of tuberculosis, but patient B, in whom bronchoscope was washed immediately before the patients who underwent bronchoscopy using the same bronchoscopy immediately before the patient C, had a bacteriologically confirmed tuberculosis. However, in this case, outward PCR analysis revealed that they were different strains (Fig 1).

With regard to the order in which each bronchoscope was used, two consecutive positive CA results were observed twice. In each episode, the second patient had bacteriologically confirmed tuberculosis, independent of the CA results. These results also suggest that it is unlikely that the bronchoscope caused false-positive CA results in subsequent specimens. In summary, in our study, none of the 49 bronchoscopic procedures that were performed on 43 patients with confirmed pulmonary tuberculosis caused the false-positive CA test results in subsequent bronchial aspirate specimens.
Figure 1. Outward PCR analysis in a case (C) with a positive CA result in which contamination was suspected through the washing procedure showed a different pattern of bands compared with that in a case (B) which was suspected to be the origin of contamination. A: Lambda/Hind DNA marker. B: Possible source of contamination. C: Contamination-suspected sample. D: H37Rv. E: Negative control.