Daily and weekly urine variations in bacterial growth susceptibility in postmenopausal women with no history of urinary tract infection: a pilot study

Abstract

ObjectivesTo evaluate bacterial growth in the bladder as a major virulence factor during urinary tract infections (UTIs), we assessed the variability of uropathogenic bacterial growth in urine samples over multiple timepoints from three postmenopausal women with no history of UTI. MethodsFollowing IRB approval, postmenopausal women who never had a UTI provided mid-stream urine samples three times daily (8 a.m., 12 p.m. and 4 p.m.), twice a week over two weeks, as well as dietary intake logs. Each sample was studied for pH and bacterial growth using three uropathogenic Escherichia coli (E.coli) strains (LRPF007, KE40, UTI89), one uropathogenic Enterococcus faecalis strain (HRH40), and one non-pathogenic E. coli strain (W3110). ResultsSimilar mean growth yields were observed for the uropathogenic strains (mean ∆OD600 = 0.1 – 0.13) with high variability (standard deviation (SD) = 0.13 – 0.28) and lower mean growth for the non-pathogenic strain (mean ∆OD600 = 0.05). Urine from each individual at different collection times never had the same bacterial growth potential for any bacterial strain. There were significant associations between urine pH decrease with higher fat (p=0.017), vitamin D (p=0.02), magnesium (p=0.049), fluid (p=0.013), and ash (p=0.01) intake. ConclusionsMajor variations were observed in the bacterial growth response in the urine of the same individuals. These variations imply a requirement for a normalization procedure, e.g., growth in synthetic urine, for analysis of bacterial growth in urine. There were significant associations between decreased urine pH and several nutrients found in foods that are classified as highly acidic.