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The following is a summary of “Daily and weekly urine variations in bacterial growth susceptibility in postmenopausal women with no history of urinary tract infection: a pilot study,” published in the September 2024 issue of Urology by Papp et al.
This study aimed to evaluate the variability of uropathogenic bacterial growth in the urine of postmenopausal women without a history of urinary tract infections (UTIs), focusing on understanding how urine composition and dietary factors influence bacterial proliferation—a critical aspect of UTI virulence. By assessing bacterial growth across multiple time points and correlating it with urine pH and dietary intake, this study sought to provide insights into the complexities of bacterial behavior in the bladder environment.
Following Institutional Review Board (IRB) approval, three postmenopausal women with no prior UTIs provided mid-stream urine samples three times daily (8 a.m., 12 p.m., and 4 p.m.) on two separate days each week over two weeks. The study also required participants to maintain detailed dietary logs. Each urine sample was analyzed 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) as a control.
The results revealed a notable variability in bacterial growth potential across different urine samples from the same individuals. The mean optical density (∆OD600) for the uropathogenic strains ranged from 0.1 to 0.13, with a high standard deviation (SD = 0.13 – 0.28), indicating significant fluctuations in growth potential. In contrast, the non-pathogenic E. coli strain exhibited a lower mean growth (mean ∆OD600 = 0.05), further underscoring the differential response of pathogenic versus non-pathogenic strains to urine conditions. Importantly, no urine sample from a single individual consistently demonstrated the same bacterial growth potential across different time points for any bacterial strain tested.
Additionally, a significant association was observed between a decrease in urine pH and the intake of certain nutrients, including higher fat (p=0.017), vitamin D (p=0.02), magnesium (p=0.049), fluid (p=0.013), and ash (p=0.01) content, which are commonly found in acidic foods.
In conclusion, the substantial variations in bacterial growth potential observed in urine from the same individuals highlight the need for standardized normalization procedures, such as growth in synthetic urine, to accurately analyze bacterial behavior in urinary studies. Furthermore, the significant correlation between decreased urine pH and specific dietary nutrients suggests that diet modulates the bladder environment, potentially influencing susceptibility to UTIs. These findings emphasize the importance of considering individual variability and dietary factors in UTI research and clinical practice.
Source: sciencedirect.com/science/article/abs/pii/S0090429524007672
