The bladder is not sterile: History and current discoveries on the urinary microbiome

Abstract

In the human body, there are 10 bacterial cells for every one human cell. This fact highlights the importance of the National institutes of Health's initiative to map the human microbiome. The Human Microbiome Project was the first large-scale mapping of the human microbiome of 5 body sites: GI tract, mouth, vagina, skin and nasal cavity using culture-independent methods. The bladder was not originally tested because it was considered to be sterile and there were complexities regarding sample collection. Over the last couple years our team along with other investigators have shown that a urinary microbiome exists and for most individuals it plays a protective role.

Keywords: Urinary microbiome; bacteria; urgency incontinence.

Figure 1

Sequencing Technologies

Figure 2. Relative Abundance of urgency urinary incontinence (UUI) patients versus continent controls

Here is shown the bacterial community structure in terms of percentage of total classified reads (y-axis) per sample collected (x-axis) from previously published data [21]. Each color represents a different taxonomic classification at the Family or Genus level. Some urine samples were dominated by Lactobacillus (blue) or Gardnerella (red) or by the family Enterobacteriaceae (green), which includes Escherichia, Klebsiella, and Proteus. In other samples, no bacterium dominated; these were termed “diverse.” The UUI cohort has more individuals in the Gardnerella urotype and tends to be more diverse overall than the continent controls.