Urinary microbiome altered in urge incontinence

By Joanna Lyford, Senior medwireNews Reporter

The frequency and nature of bacteria in the urinary tract differs significantly between healthy women and those with urge incontinence, a US study demonstrates.

The findings suggest that the urinary microbiome plays a role in female urinary health and disease, say Alan Wolfe (Loyola University Chicago, Maywood, Illinois, USA) and co-authors writing in the American Society for Microbiology's online journal mBio.

Because the symptoms of urge incontinence overlap those of urinary infection, Wolfe’s team compared the urinary microbiome in 60 women with urge incontinence and 58 women without.

Bacteria were isolated from urine collected using a transurethral catheter and classified using 16S rRNA gene sequencing and expanded quantitative urine culture. Bacterial DNA was detected in 63.9% of women with urge incontinence and 65.8% of control women, although the authors note that the failure to detect bacteria might reflect methodological issues rather than an actual absence of bacteria.

Further analysis of samples with detectable bacterial DNA revealed “important differences” in the microbiomes of the two groups, say Wolfe et al. Nine genera – Actinobaculum, Actinomyces, Aerococcus, Arthrobacter, Corynebacterium, Gardnerella, Oligella, Staphylococcus and Streptococcus – were significantly more prevalent in samples from the urge incontinence women than from control women.

Indeed, four of these genera – Actinobaculum, Aerococcus, Arthrobacter and Oligella – were not found in any sample from controls.

Lactobacillus was found in both groups (43% in urge incontinence women vs 60% in controls). However, there were significant differences at the species level, with Lactobacillus gasseri being significantly more prevalent in women with urge incontinence and Lactobacillus crispatus predominating in healthy controls.

The researchers admit that the explanation for their findings is unclear. One possibility is that the bladder in women with urge incontinence selects for some bacteria over others; the presence of these organisms in the bladder could thus serve as a marker for dysbiosis.

“Another possibility is that these bacteria contribute to [urge incontinence] symptoms, a supposition supported by the observation that each of the genera associated with the [urge incontinence] cohort contains at least one reported pathogenic species”, they say.

“Taken together, this study, along with others, will eventually allow us to define a core or common urinary microbiome that can be used to detect alterations to that community,” the authors conclude.

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