Correlation between Specific Bacterial Groups in the Oral Cavity and the Severity of Halitosis: Any Possible Beneficial Role for Selected Lactobacilli?

Objective: Halitosis is a widespread problem, normally attributable to specific volatile sulphur compounds (VSC) in the breath. The aim of this study was to first relate halitosis with possible gastric infection by Helicobacter pylori and secondly to quantify specific bacterial groups in the oral cavity flora, thus correlating them with VSC concentrations and Proton Pump Inhibitors (PPIs) intake. Four selected lactobacilli were then assessed in the possible reduction of halitosis in subjects with a total salivary bacterial concentration higher than 105 CFU/ml. Methods: Specific bacterial groups, namely total bacteria, total coliforms, sulphite-reducing bacteria (SRB) and lactobacilli, were quantified in samples of saliva from 29 subjects taking PPIs compared with 36 control subjects. The amount of the three VSC hydrogen sulfide (H2S), methyl mercaptan (CH3SH) and dimethyl sulfide (CH3)2S in the breath and the presence of H. pylori were determined. Results: No significant correlation was found between H. pylori and halitosis as well as with PPIs intake. The baseline bacterial groups quantification (log10 CFU/ml of saliva, PPI group vs. control) showed: total bacteria 8.44 vs. 4.47 (p=0.001); total coliforms 4.95 vs. 2.82 (p=0.001); sulfite-reducing bacteria 5.47 vs. 2.58 (p=0.052); total lactobacilli 4.00 vs. 2.36 (p=0.016). After 15 days of lactobacilli supplementation, the same parameters (d15 vs baseline) gave: total bacteria 7.92 vs. 8.44 (p=0.019); total coliforms 3.13 vs. 4.95 (p=0.001); sulfite-reducing bacteria 4.69 vs. 5.47 (p=0.047); total lactobacilli 7.86 vs. 4.00 (p=0.048). No statistically significant differences were noted in VSC concentrations at any time. Conclusions: The intake of PPIs directly correlated with the overgrowth of specific bacterial groups in the oral cavity, but there was no correlation with H. pylori or with VSC concentration. The significant reduction in all the bacterial groups analysed after two weeks suggested the improvement of the overall oral flora in subjects chronically treated with PPIs.