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The Urethral Microbiota – A Missing Link in the Female Urinary Microbiota

Chen YB1, Hochstedler B2, Pham TT1, Acevedo Alvarez M1, Mueller ER1, Wolfe AJ2.

J Urol. 2020 Mar 2:101097JU0000000000000910. doi: 10.1097/JU.0000000000000910. [Epub ahead of print]



To examine the urethral microbiota, determine if it differs from the bladder urinary microbiome, and assess if its composition differs based on patient demographic factors and presence of lower urinary tract symptoms.


Patients presenting to our Urogynecology clinic were enrolled. Demographic information and responses to the Pelvic Floor Distress Inventory questionnaire were collected. All participants provided mid-stream voided urine, peri-urethral swab, transurethral swab, and catheterized urine samples, which were analyzed by Expanded Quantitative Urine Culture and MALDI-TOF mass spectrometry. Bray-Curtis dissimilarity analysis assessed diversity between sample types for each participant. Kruskal-Wallis, Chi-square, McNemar, Wilcoxon signed-rank, and Fisher’s exact tests tested for significance.


Forty-nine patients participated. Bladder microbiota were dissimilar to urethral, peri-urethral, and voided urine microbiota (p<0.0001). Urethral and peri-urethral microbiota were similar (p>0.05), but the urethral microbiota were dissimilar to voided urine microbiota (p=0.001), while the peri-urethral microbiota were not (p>0.05). Women under age 55 were more likely to be sexually active, premenopausal, and Hispanic, compared to women 55 years and older. Women in the younger cohort had Lactobacillus and Gardnerella cultured from urethral samples more frequently and more abundantly than women in the older cohort. There was no significant association between lower urinary tract symptoms and the frequency or abundance of urethral bacteria species.


Niches of microbiota along the female lower urinary tract may be influenced by age, menopausal status, and sexual activity. More research is needed to determine the function and clinical significance of the urethral microbiome.