Background: We compared the risks of emergence of resistance associated with four antipseudomonal agents: ciprofloxacin, ceftazidime, imipenem, and piperacillin. Methods: A cohort study, comparing the relative risks for emergence of resistance in 5 cohorts. The first cohort included all the patients from which PA was isolated that were treated with any of the study drugs. In this cohort the outcome was the emergence of resistance to any of the agents. From the same population four other cohorts were defined according to the susceptibility of the baseline isolate to the study drugs. In each of these cohorts the hazard ratios for emergence of resistance to the individual agent was examined (e.g. the risk of ceftazidime resistance associated with ceftazidime use). Results: 274 patients (followed for 3810 days) from whom PA were isolated were treated with the study agents. Resistance emerged in 28 patients (10.2%). Adjusted hazard ratios for emergence of resistance in the first cohort were: ceftazidime 0.7 (p=0.4), ciprofloxacin 0.8 (p=0.6), imipenem 2.8 (p=0.02), and piperacillin 1.7 (p=0.3). In the four other cohorts hazard ratios for emergence of resistance to each individual agent were: ceftazidime 0.8 (p=0.7), ciprofloxacin 9.2 (p=0.04), imipenem 44 (p=0.001), and piperacillin 5.2 (0.01). Conclusions: The likelihood of emergence of resistance following treatment differ between the study antipseudomonal agents. Ceftazidime was associated with the lowest risk, ciprofloxacin and piperacillin with an intermediate risk, and imipenem with the highest risk.
|Number of pages||1|
|Journal||Clinical Infectious Diseases|
|State||Published - 1997|