Clinically relevant epithelial lining fluid concentrations of meropenem with ciprofloxacin provide synergistic killing and resistance suppression of hypermutable Pseudomonas aeruginosa in a dynamic biofilm model.

Clinically relevant epithelial lining fluid concentrations of meropenem with ciprofloxacin provide synergistic killing and resistance suppression of hypermutable Pseudomonas aeruginosa in a dynamic biofilm model. Antimicrob Agents Chemother. 2020 May 04;: Authors: Bilal H, Bergen PJ, Tait JR, Wallis SC, Peleg AY, Roberts JA, Oliver A, Nation RL, Landersdorfer CB Abstract Treatment of exacerbations of chronic Pseudomonas aeruginosa infections in patients with cystic fibrosis (CF) is highly challenging due to hypermutability, biofilm formation and an increased risk of resistance emergence. We evaluated the impact of ciprofloxacin and meropenem as monotherapy and in combination in the dynamic in vitro CDC biofilm reactor (CBR). Two hypermutable P. aeruginosa strains, PAOΔmutS (MICciprofloxacin 0.25 mg/L, MICmeropenem 2 mg/L) and CW44 (MICciprofloxacin 0.5 mg/L, MICmeropenem 4 mg/L), were investigated for 120h. Concentration-time profiles achievable in epithelial lining fluid (ELF) following FDA-approved doses were simulated in the CBR. Treatments were ciprofloxacin 0.4g every 8h as 1h-infusions (80% ELF penetration), meropenem 6 g/day as continuous infusion (CI; 30% and 60% ELF penetration) and their combinations. Counts of total and less-susceptible planktonic and biofilm bacteria and MICs were determined. Antibiotic concentrations were quantified by UHPLC-PDA. For both strains, all monotherapies failed with substantial regrowth and r...
Source: Antimicrobial Agents and Chemotherapy - Category: Microbiology Authors: Tags: Antimicrob Agents Chemother Source Type: research