The effects of smoking and drinking on the oral and esophageal microbiota of healthy people

Background: To explore the effects of smoking and drinking on the microbiota in the saliva and three segments of the esophagus (upper, middle, and lower) in healthy individuals. Methods: Paired saliva and brush specimens were obtained from 76 participants who underwent upper gastrointestinal (UGI) endoscopic examination for UGI cancer screening. The esophageal microbiota was investigated by 16S rRNA gene profiling via next-generation sequencing. Results: The saliva samples from non-smoking and non-drinking participants had a greater abundance of Neisseria, Prevotella, Porphyromonas, and Rothia, and lower levels of Streptococcus, Actinobacillus, and Haemophilus compared to the esophagus. There were no significant differences in the abundance of most bacterial genera in the upper, middle, and lower oesophagus. Similarly, in the saliva of patients who smoke and drink, there was a higher prevalence of Neisseria, Prevotella, Porphyromonas, Fusobacterium, and Rothia, and a lower prevalence of Streptococcus, Actinobacillus, and Haemophilus compared to the esophagus. There were no significant differences in the abundance of most genera in the upper, middle, and lower esophagus of patients with a history of drinking and smoking. There were slight differences in the microbiota between smoking and drinking individuals and non-smoking and non-drinking individuals. Conclusions: This pilot study demonstrated microbial diversity at different taxonomic levels in the oral cavity and esophagus of non-drinking and non-smoking individuals, as well as healthy people who drink and smoke . There was a slight difference in the microbiota between non-drinking and non-smoking people and individuals with a history of drinking and smoking. These results suggested that oral or esophageal cancer caused by smoking and drinking may not be mediated by mechanisms that affect surface microorganisms.