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Pulmonary tuberculosis (TB) and bacterial pneumonia are both characterized by fever, cough, and purulent sputum production. Although TB alone can cause these symptoms, the possibility of a concomitant bacterial pneumonia has led some clinicians to treat these patients empirically with antibacterial agents. Neither the benefit of such empiric antibiotic therapy nor transtracheal aspirate cultures from patients with pulmonary TB have yielded consistent results. Consequently, we performed a prospective study to obtain lower airway secretions via a bronchoscopic protected specimen brush (PSB) technique for quantitative aerobic and anaerobic cultures from untreated patients with extensive pulmonary TB (defined as cavitary disease or involvement of > or = 3 segments). We obtained bronchoscopic samples from 3 untreated men aged 21, 61, and 60 years with extensive pulmonary TB. There was no significant bacterial growth (aerobic or anaerobic) from the specimens obtained. These results, therefore, do not support the hypothesis that bacterial pneumonia is a common concomitant of extensive pulmonary TB.

Despite marked improvements in antibiotic therapy, the accurate diagnosis and treatment of bacterial lower respiratory tract infection remain a challenge. The bronchoscopic protected specimen brush and bronchoscopic bronchoalveolar lavage combined with quantitative bacterial cultures can provide sensitive and relatively specific information about lower airway flora. Both of these methods require strict observance of the required protocol, careful processing of the obtained specimens, and the absence of prior antibiotic therapy to obtain best results. These procedures are also of some utility in sickle cell acute chest syndrome, bronchiectasis, and in the immunocompromised host.

We prospectively compared the usefulness of a bronchoscopic protected catheter technique with the results from sputum cultures in the evaluation of moxalactam, a new beta-lactam antibiotic. The significance of a given isolate on protected catheter culture was determined by quantitative bacteriology. 32 patients with community-acquired pneumonia were enrolled in the study and 31 grew common lower respiratory tract pathogens from their protected catheter specimen. The most common single pathogens recovered were Streptococcus pneumoniae (11 patients) and Haemophilus influenzae (2). Mixed flora, predominantly anaerobes, were isolated from 15 patients, and 3 patients had mixed aerobic infections. All seven bacteremic cases had the identical organism isolated from the protected catheter specimen, confirming the accuracy of the technique. Comparisons with sputum cultures showed that the predominant organism on sputum culture was the same as that obtained from the protected catheter culture in only 13% of the cases. Sputum cultures revealed either no pathogen or a different pathogen in 23 cases, and no sputum could be obtained in 4. Compared to cultures of expectorated sputum, we found the protected catheter bronchoscopic culture technique to have the following advantages in the bacteriologic evaluation of moxalactam: 1) greater accuracy and sensitivity in bacteremic patients; 2) accurate delineation of the bacteriology of infections; and 3) a higher percentage of patients with evaluable bacteriology leading to greater efficiency during the investigation.

Quantitative bacteriology was performed on specimens collected by protected catheter fiberoptic bronchoscopy from 172 patients. Of the patients who had pneumonia, 75 of 78 (96%) had one or more species present at greater than or equal to 10(3) CFU/ml, whereas 2 of 35 (6%) control patients had organisms present in that quantity. In addition, 66% of the control specimens yielded no isolates by this technique. All of the 11 patients with bronchitis had greater than or equal to 10(3) CFU/ml. Quantitative bacteriology revealed high levels of colonization in patients without infection and endobronchial structural disease. The data suggest that bacterial counts of greater than or equal to 10(3) CFU/ml in suspended secretions collected with a protected catheter brush were diagnostic of the bacteriological etiology of lower respiratory tract infections in patients without endobronchial structural abnormalities.