The urobiome in men and women: a clinical review.

BACKGROUND: Antibiotic therapy alone is unable to control recurrent urinary tract infection (UTI); uropathogens have become multiresistant and alternative strategies are needed. Far from sterile, the urinary tract contains various low-biomass microbiota, some of whose members appear to protect against clinical UTI.

OBJECTIVES: This narrative review summarises (1) current knowledge of the male and female urobiomes in healthy and diseased states, as well as their interplay among sexual partners, and (2) clinical trials to date assessing probiotic and other non-antibiotic measures to reduce UTI.

SOURCES: We used the Pubmed interface to search Ovid Medline for articles describing urogenital flora, UTI, UTI dysbiosis, the effects of sexual intercourse on urogenital flora, and clinical trials of probiotics as UTI prophylaxis.

CONTENT: The healthy urobiome of women contains several Lactobacillus species, some of which may impede E. coli growth in the urinary tract. While Lactobacilli have been found in male urethral microbiota, their presence in male bladder microbiota is less certain. Distal male urethral and vaginal microbiomes of male and sexual female partners influence one another, but more research is needed on the direct interplay of their full urobiomes. Clinical trials assessing the therapeutic potential of Lactobacilli have been largely underpowered and highly varied in tested formulations and routes and frequencies of administration; as such they have failed to show a clear benefit. Fecal microbiota transplantation (FMT) for recurrent Clostridium difficile infection was shown, in a retrospective study of seven patients, to reduce recurrent UTI as a side effect.

IMPLICATIONS: The urobiome in men and women is complex, variable, and still understudied. While there is hope that Lactobacilli and FMT could be future non-antibiotic options for recurrent UTI, both require more pharmacologic and clinical research to identify optimal preparations and routes of administration.