Carbenicillin: A Clinical and Laboratory Evaluation

Carbenicillin therapy was given for Gram-negative infections, especially those due to Pseudomonas aeruginosa. In vitro studies demonstrated antibacterial activity against P. aeruginosa only at high drug concentrations. Forty-five patients with Gram-negative infections, including 38 due to Pseudomonas, were treated with carbenicillin. Therapy was successful in 10 patients, resulted in improvement in 19, and was considered a failure or indeterminate in 16 patients. Nine additional patients with Gram-negative infections were treated with carbenicillin and gentamicin; three were successfully treated; two improved; and four were failures or indeterminate. Carbenicillin was most effective in treating pseudomonas urinary-tract infections, although the relapse rate was high. Results of therapy for bacteremia, pneumonia, and other foci of infection were far less satisfactory, partly because of the serious nature of underlying disease. Carbenicillin-resistant Pseudomonas strains emerged during therapy in four patients. No serious drug toxicity was encountered, but superinfection was frequent.