Sampling lower respiratory tract secretions in primary lung abscess: a comparison of the accuracy of four methods.

To determine the relative cultural accuracy of transtracheal aspiration (TTA), wire-brushing under direct vision through a flexible fiberoptic bronchoscope (WBB), and expectorated sputum (ES) in localized pulmonary infections, we compared each method with percutaneous needle lung aspiration (PLA) cultures in patients with peripheral lung abscesses. Of the 27 organisms that PLA cultures isolated from ten lung abscesses (eight aerobic, two anaerobic), TTA identified 81 percent plus an additional five, and WBB 68 percent plus 16. Of the 14 organisms that PLA cultures isolated from eight aerobic abscesses, TTA identified 93 percent plus an additional two, WBB 83 percent plus 12, and ES 71 percent plus 19. From a laboratory standpoint, we concluded the following: (1) when PLA cultures cannot be obtained, the most accurate method for determining the cause of a localized pulmonary infection is TTA generates false-negative and false-positive information, it may not be an appropriate standard to evaluate other methods, such as ES.