Diagnosis of bacterial pulmonary infections with quantitative protected catheter cultures obtained during bronchoscopy

Abstract

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 ≥103 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 ≥103 CFU/ml. Quantitative bacteriology revealed high levels of colonization in patients without infection and endobronchial structural disease. The data suggest that bacterial counts of ≥103 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.