Daptomycin versus ciprofloxacin in the treatment of Complicated urinary tract infection due to Gram-positive bacteria

Background: Complicated urinary tract infections (UTIs) due to Gram-positive pathogens are of increasing concern because of steadily emerging resistance to standard antibiotic therapy. Daptomycin is the first available agent of a new class of antibiotics, the cyclic lipopeptides, which have bactericidal activity against a broad range of Gram-positive pathogens including organisms resistant to methicillin, vancomycin, and other currently available agents. The purpose of this study was to compare the efficacy and safety of daptomycin with ciprofloxacin in the treatment of adult patients with complicated, Gram-positive UTIs. Methods: A total of 68 adult patients with complicated UTIs predominantly caused by Gram-positive pathogens were enrolled in an open-label, microbiologist-blinded trial. Complicated UTI was defined as pyuria and bacteriuria (≥10 5 colony-forming units/mL), and at least 1 underlying urinary tract complication, such as recent urinary tract surgery, postvoiding residual volume, neurogenic bladder, calculi (renal, ureteral, or bladder), urinary tract obstruction, surgically reconstructed bladder, or bladder diverticulum. Patients were randomized to receive intravenous daptomycin (4 mg/kg every 24 hours) or intravenous ciprofloxacin (400 mg every 12 hours) for 5 to 14 days. The primary efficacy end points were microbiologic and clinical response at the test-of-cure visit. The major statistical objective was to demonstrate noninferiority of daptomycin to ciprofloxacin. Results: For the microbiologically evaluable population, bacteriologic eradication at test-of-cure was 83% for daptomycin and 85% for ciprofloxacin (95% confidence interval [ciprofloxacin-daptomycin]: -17.7, 21.4). Clinical success rates at test-of-cure were 93% and 94%, respectively (95% confidence interval: -13.6, 12.2). Successful clinical outcome at the follow-up visit was maintained in 93% of daptomycin patients and in 86% of ciprofloxacin patients (95% confidence interval: -23.3, 8.5). Enterococcus faecalis and Staphylococcus aureus, the most common Gram-positive pathogens, were eradicated at 82% and 75%, respectively, in the daptomycin group and at 86% and 75%, respectively, in the ciprofloxacin group. Overall, there was a significantly lower incidence of adverse events in the daptomycin group than in the ciprofloxacin group, primarily due to fewer gastrointestinal disorders for daptomycin (95% confidence interval: 0.7, 28.7). There was no reported muscle pain or weakness in the entire safety population. Conclusion: Although low enrollment compromised the statistical power of the study, a trend toward equivalent efficacy between intravenous daptomycin and intravenous ciprofloxacin was observed. Daptomycin warrants further investigation as a potential agent for the treatment of complicated UTI due to Gram-positive pathogens.