Antimicrobial Activity of Urine after Ingestion of Differing Daily Doses of Cranberry Juice Cocktail in Pregnancy: A Pilot Study

The objective of this study is to evaluate in vitro antimicrobial activity of urine from pregnant subjects following cranberry juice cocktail (CJC) or placebo ingestion against common pathogens causing asymptomatic bacteriuria. This study was conducted as an adjunct to a larger randomized, controlled trial. 4-hour uninfected urine samples were collected from 28 pregnant women who were randomized to cranberry or placebo in three groups: A. CJC 240 ml two times daily (C, C; n=10), B: CJC in the AM, then placebo in the PM (C, P; n=10), C: placebo two times daily (P, P; n=8). The pH of all specimens was adjusted to 7 and filtered. Aliquots were independently inoculated with overnight culture of 10 2-3 cell/ml each of single strains of E. coli with both type I and type II fimbriae, K. pneumoniae, and C. albicans, and incubated. CFU/ml of each specimen was enumerated by subculture with quantitative plate counts in duplicate. There were no differences between groups for any of the pathogens studies based on treatment allocation. We demonstrated no differences in direct antimicrobial activity against E. coli, K. pneumonia or C. albicans in the urine of pregnant based on differing daily cranberry doses. This may be due to beta-error.