It has been reported that cigarette smoking is a risk factor for bacterial pneumonia and other respiratory infections, and that smokers are more likely to harbor bacterial pathogens in their oral and nasopharyngeal cavities than nonsmokers. Effects of tobacco smoke and its constituents on immune function and mucociliary clearance have been proposed as underlying causes of these associations, but the possible role of cigarettes as a direct source of bacterial pathogen exposures has not been comprehensively assessed. Sapkota et al. used a 16S rRNA-based taxonomic microarray approach to characterize bacteria present in four different brands of commercially available cigarettes.