Bacteriophages of the lower urinary tract

The discovery of bacteria in the female urinary bladder has fundamentally changed current dogma regarding the urinary tract and related urinary disorders. Previous research characterized many of the bacterial components of the female urinary tract, but the viral fraction of this community is largely unknown. Viruses within the human microbiota far outnumber bacterial cells, with the most abundant viruses being those that infect bacteria (bacteriophages). Similar to observations within the microbiota of the gut and oral cavity, preliminary surveys of the urinary tract and bladder microbiota indicate a rich diversity of uncharacterized bacteriophage (phage) species. Phages are vital members of the microbiota, having critical roles in shaping bacterial metabolism and community structure. Although phages have been discovered in the urinary tract, such as phages that infect Escherichia coli, sampling them is challenging owing to low biomass, possible contamination when using non-invasive methods and the invasiveness of methods that reduce the potential for contamination. Phages could influence bladder health, but an understanding of the association between phage communities, bacterial populations and bladder health is in its infancy. However, evidence suggests that phages can defend the host against pathogenic bacteria and, therefore, modulation of the microbiome using phages has therapeutic potential for lower urinary tract symptoms. Furthermore, as natural predators of bacteria, phages have garnered renewed interest for their use as antimicrobial agents, for instance, in the treatment of urinary tract infections.