Molecular Basis of Tobacco‐Induced Bacterial Biofilms

Objective To evaluate changes in the expression of biofilm‐related genes when exposed to tobacco smoke and oxidative stress. Study Design Experimental, in vitro. Setting Laboratories of Rhinology and Microbiology, University of Pennsylvania. Subjects and Methods Bacterial biofilm mass was measured using crystal violet staining and measurement of the optical density. Biofilm‐related genes of the Pseudomonas aeruginosa PAO1 strain (pilF, flgK, lasI, lasB, rhlA, and algC) were studied following repetitive exposure to exogenous tobacco smoke and hydrogen peroxide. This was done using a reporter plasmid. Results After 1 exposure to smoke, there was no change in biofilm formation. However, after 2 and 3 exposures, the biofilm formed had an increased mass (P