Multidrug-resistant Gram-negative bacilli causing urinary tract infections: clinical considerations.

摘要

In this issus of The Journal of Chemotherapy, the article by Drekonja et al. presents a case and reviews the literature on tigecycline treatment of urinary tract infections (UTIs).1 Their article raises several important clinical and pharmacokinetic concerns which are the focus of this commentary. There are three topics relevant to their case that deserve comment. Firstly, not to be overlooked is the critical role of ciprofloxacin in inducing resistance. Ciprofloxacin was most likely responsible for the previously susceptible strain of ￡s-cherichia coli becoming multidrug resistant (MDR). It is a common misconception that antibiotic resistance is a class phenomenon. Rather, resistance potential is a property of individual antimicrobial(s) within each antibiotic class. Among the quinolones, ciprofloxacin has a "high resistance potential" and is the quinolone most likely to induce resistance in aerobic Gram-negative bacillus (GNBs), e.g., E. coli in this case.2'3 Even short courses of "high resistance potential" antibiotics, e.g., ampicillin, trimethoprim-sulfamethoxazole (TMP-SMX), ciprofloxacin may induce resistance in the fecal flora that may persist after cessation of therapy. Levofloxacin and moxifloxacin are "low resistance potential" antibiotics and are less likely to induce resistance. From a resistance perspective, levofloxacin is preferred to ciprofloxacin for the treatment of UTIs including those due to Pseudomonas aeruginosa. Also, from a clinical outcomes perspective, levofloxacin is at least as good, if not more effective, than ciprofloxacin for P. aeruginosa UTIs.