In-vitro activity of ciprofloxacin and other antibacterial agents against Pseudomonas aeruginosa and Pseudomonas cepacia from cystic fibrosis patients.

The in-vitro activities of ciprofloxacin, a new oxyquinoline derivative, norfloxacin and six anti-pseudomal beta-lactam antibiotics were tested against pulmonary isolates of smooth and mucoid colony forms of Pseudomonas aeruginosa, and Ps. cepacia from children with cystic fibrosis. Ciprofloxacin was the most effective of the agents tested against either species. Minimal inhibitory concentrations of ciprofloxacin were 0.5, and 16 mg/l, for 90% of the Ps. aeruginosa and Ps. cepacia strains tested, respectively. No effect of inoculum size or discordance between inhibitory or bactericidal concentrations was observed. Ciprofloxacin is a potentially useful agent for the treatment of acute pseudomonal pulmonary exacerbations in children with cystic fibrosis.