Abstract
It is often difficult to determine the pathogenic microorganism responsible for a respiratory tract infection by bacteriological examinations of the sputa. The primary difficulty resides in the fact that sputa are commonly contaminated with oral and pharyngeal microbes. The transtracheal aspiration (TTA) developed by Pecora aims at minimizing this contamination by collecting tracheal washings proximal to the site of infection. By employing a modified TTA we have studied 158 aspirates from 113 patients with various respiratory diseases. The results of our study are summarized as follows:
1. A single bacterial strain was cultured more frequently from transtracheal aspirates than from sputa and contamination with oropharyngeal microbes was definitely uncommon in the former. Pathogenic organisms cultured from transtracheal aspirates corresponded with those from sputa in about 50% of the cases. When all bacteria regardless of their pathogenicity were taken into consideration, cultures from the 2 origins corresponded to a lesser extent.
2. Washed sputa and bronchoscopic washings were not free from the contamination with so-called normal oral microbes.
3. Possibly reflecting the influence of chemotheraphy prior to bacteriological examinations, only about a half of the patients with acute respiratory tract infections gave positive bacterial cultures by TTA. The incidence of positive culture was 44% in chronic respiratory tract infections, and 95% in bronchiectasis, respectively. Not infrequently the activity of chronic bronchitis appeared to be related with nonbacterial stimuli.
4. The most common intrabronchial microorganism found in bacterial pneumonia was pneumococcus which disappeared promptly after appropriate chemotherapy. In chronic respiratory tract infections, intrabronchial microbial flora changed in parallel with the clinical picture of the patients. Symptomatic fluctuation, aggravation, and therapy-resistance were reflected either by the persistence of gram negative rods or superinfection.
The foregoing results indicate that TTA as compared with examinations of sputa, washed sputa, and bronchoscopic washings is the most reliable method of studying intrabronchial microbial flora.
