Effect of tobacco tar on Staphylococcus aureus and Candida albicans biofilm formation

Twenty compounds were determined in the tar of cigarette smoke. The tar was obtained using tobacco filters and then analyzed by liquid chromatography-mass spectrometry (LC-MS). Tobacco tar expressed marked decrease in the susceptibility of Staphylococcus aureus to penicillin, tetracycline and amoxicillin/clavulanic antibiotics and showed marked decrease in susceptibility of Candida albicans to the tested antifungals except for clotrimazole and ketoconazole. Tobacco tar decreased the permeability of the tested organisms to ethidium bromide in the presence of antimicrobials, after 2 h for both S. aureus (17.8-20%) and C. albicans (13.3-16.3%) and decreased the adherence of the tested microorganisms at concentrations above Minimal Inhibitory Concentration (MIC). Tobacco tar showed a marked increase in the hydrophobicity of the tested microorganisms by 2.5 to 7 fold. Tobacco tar increased or upregulated ALS1 and HWP1 genes that play an important role in adhesion, hyphae formation and biofilm formation of C. albicans and increased the expression of ica A gene that regulate biofilm formation of S. aureus.