The Prevalence of Polyketide Synthase-Positive E. coli in Cystic Fibrosis

Cystic fibrosis (CF) patients experience higher risks of colorectal cancer but the pathogenesis is unclear. In the general population, polyketide synthase-positive (pks⁺) <i>E. coli</i> is implicated in intestinal carcinogenesis via the production of colibactin; however, the relevance in CF is unknown. In this study, we investigate pks⁺<i>E. coli</i> prevalence in CF and potential associations between pks⁺<i>E. coli</i>, gastrointestinal inflammation, and microbiome dynamics with fecal calprotectin and 16SrRNA gene taxonomic data. Cross-sectional analysis demonstrated no difference in pks⁺<i>E. coli</i> carriage between CF patients and healthy controls, 21/55 (38%) vs. 26/55 (47%), <i>p</i> = 0.32. Pks⁺<i>E. coli</i> was not associated with significant differences in mean (SD) calprotectin concentration (124 (154) vs. 158 (268) mg/kg; <i>p</i> = 0.60), microbial richness (159 (76.5) vs. 147 (70.4); <i>p</i> = 0.50) or Shannon diversity index (2.78 (0.77) vs. 2.65 (0.74); <i>p</i> = 0.50) in CF. Additionally, there was no association with exocrine pancreatic status (<i>p</i> = 0.2) or overall antibiotic use (<i>p</i> = 0.6). Longitudinally, CF subjects demonstrated intra-individual variation in pks⁺<i>E. coli</i> presence but no significant difference in overall prevalence. Future investigation into the effects of repeat exposure on risk profile and analysis of older CF cohorts is necessary to identify if associations with colorectal cancer exist.