Development and Validation of a Sensitive, High-Throughput Bioassay for the Adhesion of Radiolabeled E. coli to Uroepithelial Cells in Vitro

Vaccinium macrocarpon (cranberry) products have been used to prevent uropathogenic Escherichia (E.) coli adherence to uroepithelial cells (UEC) and may help reduce risk of urinary tract infection. Reported herein are the development and validation of an assay to assess antiadhesion activity of V. macrocarpon extracts and human urine. P-fimbriated E. coli (CFT073) was labeled with 3H-uridine, then co-incubated with HTB-4 UEC at a 400:1 ratio. V. macrocarpon extracts (0–17 mg proanthocyanidins/mL) were added to 3H-labeled E. coli before co-incubating with UEC. The assay yielded a sensitive inhibition curve: the lower limit of detection and half-maximal inhibitory concentration were 0.43 and 1.59 mg proanthocyanidins/mL for V. macrocarpon extract CEP 55; intra- and interassay coefficients of variance were