Since the discovery of the bladder microbiome (urobiome), interest has grown in learning whether urobiome characteristics have a role in clinical phenotyping and/or provide opportunities for novel therapeutic approaches for women with common forms of urinary incontinence (UI).
To test our hypothesis that the bladder urobiome differs between continent women and women affected by UI by assessing associations between UI status and the cultured urobiome.
With IRB oversight, transurethral catheterized urine specimens were collected from 309 adult women, who were categorized into three groups using response to the validated Pelvic Floor Distress Inventory (PFDI): Continent Controls (N=150) and 2 Urinary Incontinence (UI cohorts) - Stress Urinary Incontinence (SUI) (N=50) and Urgency Urinary Incontinence (UUI) (N=109). Symptom severity was assessed with the Urinary Distress Inventory (UDI) subscale score of the PFDI. Microbes were assessed by the Expanded Quantitative Urine Culture protocol, which detects the most common bladder microbes (bacteria and yeast). Microbes were identified to the species level by MALDI-TOF mass spectrometry. Alpha diversity indices were calculated for culture-positive samples and compared across the three groups. The association between UDI scores versus alpha diversity indices and species abundance were estimated.
Participants had a mean age of 53 years (range 22-90); most were Caucasian (65%). Women with UI were slightly older (Control=47, SUI=54, UUI=61). By design, UDI symptom scores differed (Control = 8.43 (10.1), SUI = 97.95 (55.36), UUI = 93.71 (49.12), p<0.001). While most participants (216, 70%) had Expanded Quantitative Urine Culture-detected bacteria, the UI cohorts had a higher detection frequency than did the Control cohort (Control=57%, SUI 86%, UUI 81%, p<0.001). The most frequently detected species were as follows: Controls, Lactobacillus iners (12.7%), Streptococcus anginosus (12.7%), L. crispatus (10.7%), and L. gasseri (10%); SUI, S. anginosus (26%), L. iners (18%), Staphylococcus epidermidis (18%), and L. jensenii (16%); UUI, S. anginosus (30.3%), L. gasseri (22%), Aerococcus urinae (18.3%), and Gardnerella vaginalis (17.4%). However, only Actinotignum (formerly Actinobaculum) schaalii, A. urinae, A. sanguinicola, and Corynebacterium lipophile group were found at significantly higher mean abundances in at least one of the UI cohorts when compared to the Control cohort (Wilcoxon p<0.02), and no individual genus differed significantly between the two UI cohorts. Both UI cohorts had increased alpha diversity relative to continent controls with indices of species richness, but not evenness, strongly associated with UI.
In adult women, the composition of the culturable bladder urobiome is associated with UI, regardless of common incontinence subtype. Detection of more unique living microbes was associated with worse incontinence severity. Culturable species richness is significantly greater in the UI cohorts than continent controls.
American journal of obstetrics and gynecology. 2020 May 04 [Epub ahead of print]
Travis K Price, Huaiying Lin, Xiang Gao, Krystal J Thomas-White, Evann E Hilt, Elizabeth R Mueller, Alan J Wolfe, Qunfeng Dong, Linda Brubaker
Departments of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois, USA., Department of Medicine, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois, USA., Departments of Obstetrics & Gynecology and Urology, Loyola University Medical Center, Maywood, Illinois, USA., Departments of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois, USA. Electronic address: ., Department of Medicine, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois, USA. Electronic address: ., Department of Obstetrics, Gynecology and Reproductive Sciences, Division of Female Pelvic Medicine and Reconstructive Surgery, University of California San Diego, La Jolla, California, USA. Electronic address: .