The urinary microbiota was discovered very recently and has only begun to be described. Imbalances in this flora may be associated with problems in the urinary tract.
The idea that the urinary bladder is a sterile environment and that urinary infections are related to bacteria of intestinal origin has been called into question. Recent works have shown evidence of the existence of a urinary microbiota in healthy subjects1-3 . This discovery opens an entire field of research to characterize this microbiota, determine how it is regulated, and understand its physiological and potentially pathological role. The first available data show that it is less abundant than the intestinal microbiota, with around 105 CFU* per milliliter of urine compared to 1012 CFU per gram of stool9. It also seems to be less diverse than the gastrointestinal microbiota. It includes only several dozen bacterial species, which can vary from one individual to another1,4. The genera Lactobacillus are frequently identified and less frequently Gardnerella, Streptococcus, or Corynebacterium. 4,5 . Studies are ongoing to identify the factors that influence its composition and changes, its interactions with the vaginal and intestinal microbiota, and especially its role in the onset of urinary diseases. Imbalance in this flora may be involved in urinary infections, incontinence, or prostate diseases5-8 .
*CFU: Colony-forming unit
Sources 1- Fouts DE et al. Integrated next- generation sequencing of 16S rDNA and metaproteomics differentiate the healthy urine microbiome from asymptomatic bacteriuria in neuropathic bladder associated with spinal cord injury. J Transl Med 2012;10:174.
2- Siddiqui H et al. Assessing diversity of the female urine microbiota by high throughput sequencing of 16S rDNA amplicons. BMC Microbiol 2011;11:244.
3- Wolfe AJ, et al. Evidence of uncultivated bacteria in the adult female bladder. J Clin Microbiol 2012;50:1376-83.
4- Brubaker L, Wolfe A. The female uriniary microbiota, urinary health and common urinary disorders.Annals of Translational Medicine 2017;5:34
5- Pearce MM, et al. The female urinary microbiome: a comparison of women with and without urgency urinary incontinence. MBio 2014;5:e01283-14.
6- Thomas-White KJ et al. Incontinence medication response relates to the female urinary microbiota. Int Urogynecol J 2016;27:723-33.
7- Khasriya R et al. Spectrum of bacterial colonization associated with urothelial cells from patients with chronic lower urinary tract symptoms. J Clin Microbiol 2013;51:2054-62.
8- Amarenco G, Microbiote urinaire et troubles mictionnels. Progrès en urologie 2015 ; 25, 615-627
Dysbiosis can cause multiple pathologies with repercussions on different organs.
Affecting the microbiota
There are 2 ways to affect the equilibrium of microbiota. Each of them has its own specific features.
The WHO defines probiotics as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host”.
The intestinal microbiota is an organ in its own right.
Better characterized thanks to metagenomics, it is gradually giving up its secrets. Highly diversified, it lives in close relationship with its host. Formed from birth, it is specific to each individual and fulfills different functions within the body: barrier effect, trophic, metabolic and immune functions, etc., as well as others that remain to be elucidated.
The pulmonary microbiota was unknown for a long time, since it was commonly accepted that healthy lungs are sterile. This paradigm was cast into doubt with the discovery of the various human microbiota.