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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.

Fiberoptic bronchoscopy using a protected brush catheter was done in 65 patients with suspected pulmonary infections to obtain uncontaminated specimens for culture. Quantitative aerobic and anaerobic cultures were done on each specimen. Forty-one patients had pneumonia. Ten bacteremic patients had the same organisms recovered from the catheter and blood cultures. Seven patients had received antibiotics before the procedure, and cultures grew no organisms in high concentration. In 23 of 24 remaining patients probable pathogens were recovered in high concentrations, and specific therapy resulted in clinical improvement in all of these patients. Five patients with lung abscesses and seven with necrotizing pneumonia had mixed aerobic and anaerobic organisms recovered. Twelve patients had final diagnoses of nonbacterial lung disease, and cultures were negative or revealed low concentrations of organisms. Quantitative cultures were necessary in distinguishing pathogens from nonpathogens. There were no complications. The results of this study indicate that fiberoptic bronchoscopy using a special protected catheter is an accurate and safe technique for identification of etiologic agents in lower respiratory tract infections.