(509c) Antibiotic-Dispersion Aerosols for Enhanced Eradication of Pseudomonas Aeruginosa biofilms

In this research, we have developed dry powder aerosols containing a novel combination therapy to enhance the effectiveness of common antimicrobials against Pseudomonas aeruginosa (PA) biofilm infections. Dispersion compounds aided the removal of bacteria from the biofilm community and allowed antibiotics to eliminate the pathogens. In our current investigation, we compare the efficacy of these combination formulations against in vitro biofilms formed from clinical isolates obtained from cystic fibrosis patients with biofilms formed from the PA lab strain PAO1. Assays were conducted to determine the minimum biofilm eradication concentration (MBEC™) of combination treatments against young (24 hours old) and mature (4 days old) biofilms.

Combinations of antibiotics and dispersion compounds eradicated both young and mature biofilms more effectively than the antibiotics alone, suggesting that dispersion enhanced the susceptibility of bacteria to antibiotics. Mature PA biofilms were generally less susceptible to the treatments compared to young biofilms, confirming the important role of biofilm age on treatment. However, repeat administration of combinations over 2 days significantly lowered the MBEC values to inhibition levels for planktonic bacteria (MIC levels). Different clinical isolates varied in their susceptibility to the combination formulations, suggesting that clinical testing of these novel combination treatments against mature biofilms produced from a patient’s own clinical isolates may enhance treatment.