Effect of smoking cessation on the microbial flora

Objective: To determine the effect of smoking cessation on the frequency of recovery of potential pathogens and aerobic and anaerobic interfering bacteria in the nasopharynges of smokers. Design: Nasopharyngeal cultures were taken from 20 smokers before and 12 to 15 months after cessation of smoking. Potential pathogens and aerobic and anaerobic bacteria with interfering capabilities against these organisms were identified. Results: Eleven potential pathogens (0.92 pathogens per subject) were isolated from nasopharyngeal cultures obtained from 9 individuals before smoking cessation, and 2 (0.17 per subject) were recovered from 2 individuals after smoking cessation (P <.05). Bacterial interference between 2 aerobic (alpha and nonhemolytic streptococci) and 2 anaerobic species (Prevotella and Peptostreptococcus species) and 4 potential pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pyogenes) was observed. Bacterial interference was noted in 35 instances against the 4 potential pathogens by 14 normal flora isolates that were recovered from the smokers before cessation and in 116 instances by 42 isolates after cessation (P <.01). Conclusion: To our knowledge, these findings illustrate for the first time that the high number of pathogens and low number of interfering organisms found in the nasopharynx of smokers revert to normal levels after complete cessation of smoking.