Transtracheal aspiration in diagnosis of sputum-smear--negative tuberculosis.

Of 4,200 patients admitted to an acute-care county hospital, 126 (3%) were proved to have pulmonary tuberculosis, among whom 35 (28%) had several sputum smears negative for acid-fast bacilli. On transtracheal aspiration, 31 to 35 had acid-fast bacilli in the aspirate. Eighteen of these 35 (51%) patients had associated infections caused by aerobic or anaerobic bacteria. Tuberculin skin tests were negative in 14 of 35 patients with negative sputum specimens (40%). Ten of 18 patients (56%) with associated bacterial infections had negative skin tests to purified protein derivative. Smear and culture of transtracheal aspirate for tubercle bacilli may be invaluable in establishing the diagnosis when pulmonary tuberculosis is suspected.