Oral ciprofloxacin therapy of infection caused by multiply resistant bacteria other than Pseudomonas aeruginosa.

Of 125 patients treated with ciprofloxacin at the Columbia-Presbyterian Medical Center, New York, 34 had infections due to bacteria other than Pseudomonas aeruginosa. The mean age of the patients was 50 years (19-88 years) and most had significant underlying disease. There were nine lower respiratory infections, eight urinary tract infections, eight soft tissue infections, three osteomyelitis, and three intra-abdominal infections. The pathogens were: Escherichia coli, 7 (mean MIC 0.07 mg/l); Serratia marcescens, 6 (0.2 mg/l); Enterobacter spp., 5 (0.1 mg/l); Klebsiella pneumoniae, 3 (0.1 mg/l); Proteus mirabilis, 3 (0.06 mg/l); Cutrobacter freundii, 2 (0.06 mg/l), Staphylococcus aureus, 3 (0.5 mg/l); and one each of Acinetobacter anitratus. Haemophilus, influenzae, Salmonella enteritidis, Flavobacterium meningosepticum, and Streptococcus faecalis. Of these organisms 81% were resistant to ampicillin, 70% to carbenicillin, 22% to gentamicin, 49% to cefazolin and cephalexin, and 25% to cotrimoxazole. Ten patients had concomitant Ps. aeruginosa infections. Patients were treated orally with 500 mg or 750 mg ciprofloxacin every 12 h. The overall clinical response rate was 88%, and the bacteriological response 76%, and 65% if Ps. aeruginosa is included. Resistance to ciprofloxacin developed in one Staph. aureus and one Ser. marcescens (MIC greater than 2 mg/l). Toxicity was minor. Ciprofloxacin was effective and safe therapy of infections due to Gram-negative bacteria resistant to many of the currently available oral and parenteral agents.