Association between physical activity and the prevalence of tumorigenic bacteria in the gut microbiota of Japanese adults: a cross-sectional study.

Escherichia coli harboring polyketide synthase (pks+ E. coli) has been suggested to contribute to colorectal cancer development. Physical activity is strongly associated with lower colorectal cancer risks, but its effects on pks+ E. coli remain unclear. The aim of this study was to investigate the association between pks+ E. coli prevalence and physical activity. A cross-sectional study was conducted on 222 Japanese adults (27-79-years-old, 73.9% female). Triaxial accelerometers were used to measure light-intensity physical activity, moderate-to-vigorous intensity physical activity, the physical activity level, step-count, and time spent inactive. Fecal samples collected from participants were used to determine the prevalence of pks+ E. coli. Multivariate logistic regression analysis and restricted cubic spline curves were used to examine the association between pks+ E. coli prevalence and physical activity. The prevalence of pks+ E. coli was 26.6% (59/222 participants). The adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the highest tertile with reference to the lowest tertile of physical activity variables were as follows: light-intensity physical activity (OR 0.63; 95% CI 0.26-1.5), moderate-to-vigorous intensity physical activity (OR 0.85; 95% CI 0.39-1.87), physical activity level (OR 0.69; 95% CI 0.32-1.51), step-count (OR 0.92; 95% CI 0.42-2.00) and time spent inactive (OR 1.30; 95% CI 0.58-2.93). No significant dose-response relationship was found between all physical activity variables and pks+ E. coli prevalence. Our findings did not suggest that physical activity has beneficial effects on the prevalence of pks+ E. coli. Longitudinal studies targeting a large population are needed to clarify this association.