Voided Urinary Microbiota Is Stable Over Time but Impacted by Post Void Storage

Area of Science:

• Microbiology
• Urology
• Genomics

Background:

• Recent advancements reveal a complex bacterial community in the human urinary tract, contradicting the sterile urine assumption.
• The urinary microbiota's function remains unclear, but its imbalance (dysbiosis) is linked to urinary incontinence and infections.
• Methodological variations in sample collection and storage can confound research findings on the urinary microbiome.

Purpose of the Study:

• To assess the impact of different urine collection and storage conditions on urinary microbial composition.
• To investigate the day-to-day variability of the urinary microbiota in healthy individuals.

Main Methods:

• Midstream urine samples from healthy donors were analyzed using 16S rRNA gene sequencing.
• Urine samples were stored at various temperatures (-80°C, -20°C, 4°C) and compared to fresh samples.
• Intrapersonal daily and day-to-day variations in microbiota were examined across diverse age and sex groups.

Main Results:

• Freezing urine at -80°C and -20°C maintained microbial composition comparable to fresh samples; storage at 4°C did not.
• Significant differences in alpha and beta diversity were not observed between individuals under tested conditions, except for two adult males.
• No significant intrapersonal daily or day-to-day variations in urinary microbiota composition were found in women, girls, or boys.

Conclusions:

• Freezing is an effective method for preserving urinary microbiota composition for 16S rRNA gene sequencing studies.
• Storage at 4°C is not suitable for maintaining the integrity of the urinary microbiome.
• The study validates current methodologies, supporting future research into the human urinary tract microbiome.