Use of intravenous ciprofloxacin in difficult-to-treat infections.

Intravenous ciprofloxacin was administered to 54 patients who were either critically ill or in whom oral administration was not possible. The 31 males and 23 females ranged in age from 20 to 89 years (mean, 53.2 +/- 17.8 years). Patients had "difficult-to-treat" infections, i.e., respiratory infections (15), abscesses (four intraabdominal, three lung, two soft tissue, and one intrahepatic), deep soft tissue infections (10), chronic post-traumatic osteomyelitis in exacerbation (nine), upper urinary tract infection (five), malignant external otitis (two), catheter-related bacteremia (two), and infectious endocarditis (one). Thirty patients (56 percent) had serious associated medical problems. Pathogens included Pseudomonas aeruginosa (38 isolates), Acinetobacter species (10 isolates), Enterobacter cloacae (eight isolates), Escherichia coli (two isolates), Proteus mirabilis (one isolate), Kingella kingae (one isolate), Bacteroides fragilis (eight isolates), and Peptostreptococcus species (five isolates). Minimal inhibitory concentrations of ciprofloxacin ranged from 0.003 to 2 micrograms/ml. In 39 patients, the isolated microorganisms were multi-resistant; resistance included ceftazidime and amikacin in 32 patients. In 24 patients, ciprofloxacin was given exclusively by the intravenous route at a dose of 200 mg every 12 hours; in 30 patients, treatment was completed after discontinuation of the parenteral drug with the oral preparation of ciprofloxacin at a dose of 750 mg every 12 hours. The duration of parenteral treatment ranged from six to 40 days (mean, 14.9 days). A successful clinical response was observed in 49 patients (91 percent), while five (9 percent) failed to show a response. Bacteriologic outcomes were as follows: eradication of pathogen in 33 patients (61.1 percent), persistence in 18 (33.3 percent), and relapse in three (5.6 percent), with development of resistance to ciprofloxacin in nine patients (16.7 percent) and superinfection in two patients (3.7 percent). Side effects included vein irritation at the site of the infusion (three patients), abnormal elevation in liver enzyme levels (two patients), reversible renal failure (one patient), and nausea (one patient). Parenteral ciprofloxacin is a safe, well-tolerated, and effective therapy for the critically ill patient, and can be replaced with the oral form when clinically appropriate.