Levofloxacin-ceftazidime administration regimens combat Pseudomonas aeruginosa in the hollow-fiber infection model simulating abnormal renal function in critically ill patients

Abstract

Background: The purpose of this study was to investigate the bactericidal effects of levofloxacin and ceftazidime as both monotherapy and combination therapy, and to determine their effects on resistance suppression in patients with normal and abnormal (Ccr:16–20 mL/min) renal function. Common clinical administration regimens to provide reference values were also evaluated. Methods: The 7-d hollow-fiber infection model was used to inject the Pseudomonas aeruginosa standard strain (ATCC27853). This simulated common clinical administration regimens for patients with different renal function. Ten regimens were stratified into 2 categories based on renal function, and each category contained 3 monotherapy regimens and 2 combination therapy regimens. The total and resistant populations were quantified. Drug concentrations were determined by High-performance liquid chromatography (HPLC). Results: Monotherapy regimens resulted in about 0.5-log-CFU/mL bacterial kill in the total population at 6 or 8h, whilst combination regimens resulted in 2- to 3-log-CFU/mL within 2 days. For levofloxacin monotherapy regimens in patients with normal renal function, resistance emergence was seen after 6h, and was seen at 0h in the ceftazidime monotherapy regimen, as well as in all regimens of patients with abnormal renal function. Although resistant subpopulation in combination regimens with abnormal renal function began to increase at 0h, there was a certain downward trend after 8h, while resistant population in the normal renal function group increased after 16h. Conclusions: Combination therapy had greater bactericidal efficacy and resistance inhibition compared with monotherapy. Studying combination regimens in randomized clinical trials is warranted.