Development of a Method to Determine Regional Bacterial Eradication of Dry Powder Aerosols.

Lung infections caused by the bacterium Pseudomonas aeruginosa are challenging to eradicate due to their formation of biofilms. These bacterial colonies excrete a polysaccharide matrix that provides protection to the bacteria from the immune system and antibiotics. To be effective, antibiotics must be delivered directly to the site of infection to provide the high drug concentrations required for eradication. Localized delivery can also minimize side effects experienced throughout the body with other routes of delivery. Dry powder aerosols containing antibiotics can be inhaled at high doses, thus providing a method to kill lung infections. The size and deposition of such aerosol particles can be characterized by impaction methods, such as with the Next Generation Impactor (NGI). This impactor, however, cannot support bacteria viability studies, meaning it cannot determine how well a dry powder aerosol can eradicate bacteria at various locations in the lungs. The 6-stage Viable Andersen Cascade Impactor (vACI) is commonly used in environmental studies to collect microbes, including bacteria, via impaction onto petri dishes. In the vACI, aerosolized material will deposit on the six stages based on aerodynamic size. The purpose of this research is to adapt the vACI to deposit antibiotic-containing dry powder aerosols to bacteria-laden petri dishes and quantify P. aeruginosa eradication as a function of aerodynamic size. This study aimed to determine the correlation between the deposition of dry powder aerosols in the NGI and vACI. This research will expand with the formulation of dry powder aerosols at various concentrations of ciprofloxacin to characterize how concentration of ciprofloxacin affects particle size, deposition, and lethality.