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Bronchial Aspirates in the Diagnosis of Pulmonary Tuberculosis

Bronchial Aspirates in the Diagnosis of Pulmonary TuberculosisTuberculosis is the principal cause of death due to infection worldwide. Following several decades of decline, the incidence of tuberculosis has recently begun to increase in many countries. Early diagnosis and treatment is important for the control of tuberculosis. A direct smear for acid-fast bacilli (AFB) in a sputum specimen is a simple and cheap method for the diagnosis of pulmonary tuberculosis, but has the drawback of limited sensitivity. Since 1989, various direct amplification tests (DATs) have been widely used in the diagnosis of tuberculosis. The main advantages of DATs are their rapidity and high-level sensitivity compared with direct smears for AFB, However, their benefits are compromised by the risk of false-positive results, arising from amplicon carryover or cross-contamination.
Fiberoptic bronchoscopy has been used successfully in the diagnosis of pulmonary tuberculosis in AFB smear-negative patients.2 DATs for Mycobacterium tuberculosis have also been applied to bronchial aspirate specimens, and have shown promising results. In contrast, some reports indicate that mycobacterial cross-contamination can occur during bronchoscopic procedures. Asthma inhaler in detail Because even a few dead bacilli remaining after disinfection procedures can result in an amplification product in a subsequent bronchoscopic specimen, the clinical usefulness of DATs on bronchial aspirate specimens has not yet been defined. Kaul et al reported that 2 of 55 washing solutions (3.6%) for bronchoscopes contained amplifiable M tuberculosis DNA. Carricajo et al reported an experimental case in which an amplification test on the washing fluid from a bronchoscopic channel was positive for M tuberculosis, even after the bronchoscope was disinfected by exposure to 2% glutaraldehyde for 1 h.