Penetration of cefotaxime into bronchial secretions.

The penetration into bronchial secretions of cefotaxime, a new, highly active cephalosporin, was studied in 45 patients with respiratory infections. Ten patients received 0.75 g and 25 received 1 g of cefotaxime intramuscularly; 10 patients received a 30-min intravenous infusion of 2 g of cefotaxime. Samples of bronchial secretions were obtained by means of fiber-optic bronchoscopy after a single dose in all patients and after three and seven days of treatment in 30 and 15 patients, respectively. Simultaneous serum samples were collected for determination of the relationship between the levels of drug in bronchial secretions and those in serum. Assays were performed by microbiologic agar diffusion. In 30 cases bacteriologic analysis determined the minimal inhibitory concentrations of cefotaxime for the bacteria isolated from sputum. Mean peaks in bronchial secretions reached 1.5-2.5 microgram/ml (according to the groups) after 3 hr; individual concentrations varied according to the dose, the route of administration, and the duration of the treatment. Ratios between the levels in bronchial secretions and the corresponding levels in serum were approximately 8%-25% after 3 hr, as is usual for other cephalosporins. Cefotaxime reached significant concentrations in bronchial secretions, exceeding the minimal inhibitory concentrations for microorganisms responsible for respiratory infections.