Feasibility of a surface-coated lung model for the quantification of active agent deposition for preclinical studies

Multiple drug resistance (MDR) of a growing number of bacterial pathogens represents an increasing challenge in conventional curative treatments of infectious diseases. However, the development and testing of new antibiotics is associated with a high number of animal experiments. A symmetrical parametrized lung test rig allowing the exposure of air-passage surfaces to antibiotics was designed and tested to demonstrate proof-of-principle with aerosols containing allicin, which is an antimicrobial natural product from garlic. An artificial lung surface is coated with bacteria embedded in a hydrogel and growth inhibition is visualized by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), that is reduced from colourless to the dark blue formazan in the presence of metabolically active, living cells. A nebulizer is used to generate the aerosols. The results show that allicin has an antibiotic effect as an aerosol and that the deposition pattern of the active agent occurred mainly around the carinal regions. The model represents an integral system for continuous, spatial detection of aerosol deposition and allows the analysis of bacterial behaviour and the toxicity of the active agent. In this way the deposition of antimicrobial aerosols on the bronchial surfaces is characterized in preliminary tests without any animal experiments.