Objective: The aim of the present study was to investigate the direct influence of cigarette smoke on the bacterial colonization of the lower respiratory tract and the effect of supplementary vitamin E on the colonization of instilled bacteria into the trachea of rats that do not have the chronic airway pathology associated with smoking.
Methodology: Thirty male Wistar albino rats, weighing approximately 250 g, were used as experimental animals. A 0.1 mL bacterial suspension containing six bacterial species (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumonia, Proteus mirabilis, Haemophilus influenza, Peptostreptococci spp.), isolated previously from pharynx of rats, were instilled into the trachea of three groups of rat (10 control, 10 cigarette smoke-treated and 10 cigarette smoke- and vitamin E-supplemented rats). The smoke-treated rats were exposed to cigarette smoke for 3 days prior to and after intratracheal instillation. The third group of rats were given vitamin E supplements (100 mg/kg per day). Tracheobronchial lavage samples of all rats were quantitatively cultured after 3 days from the instillation.
Results: The colony numbers of isolated bacteria were significantly higher in cigarette smoke-treated rats than in the control group and in the smoke- and vitamin E-supplemented rats (P < 0.05). Only S. aureus and S. epidermidis were isolated from vitamin E-supplemented rats, while instilled all six bacterial species were isolated from the other two groups.
Conclusions: It is concluded that smoking impairs the elimination of bacteria or facilitates colonization of bacteria in the lower respiratory tract of rats. Supplementary treatment with vitamin E reduces the effect of cigarette smoke; however, some bacteria may be resistant to this action of vitamin E.