The Role of Urinary Microbiota in Lower Urinary Tract Dysfunction: A Systematic Review.

Context: Until 2012, the urinary tract of healthy individuals was considered to be sterile. The advent of metagenomic sequencing revealed a unique urinary microbiota (UM). This paradigm shift appears to have prolific implications in the etiology of several functional lower urinary tract (LUT) disorders.

Objective: To systematically summarize recent data on the role of UM in LUT dysfunction.

Evidence Acquisition: We performed a critical review according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. We conducted a search on PubMed/MEDLINE and SCOPUS with the following MESH terms/keywords: "Microbiome OR Microbiota AND (urinary disorder OR urinary tract symptom OR overactive bladder OR urinary incontinence OR interstitial cystitis OR chronic prostatitis)." The range of search was placed between January 2010 and April 2018, and articles with no full text available or those not written in English were excluded. All retrieved papers were first reviewed by title and abstract, yielding a total of 303 papers. Additional manuscripts, such as those referenced by reviews, were further included. Thirty-six publications were included.

Evidence Synthesis: Analysis by 16S rRNA sequence and expanded quantitative urine culture provided evidence for the presence of live bacteria in urine, nondetectable by standard culture protocols. Moreover, differences in the UM between healthy individuals and patients with LUT dysfunction were demonstrated.

Conclusions: In the near future, urologists must consider urinary dysbiosis as a possible cause of different functional LUT disorders, with potential clinical implications in their diagnosis and treatment.

Patient Summary: Development of metagenomic sequencing revealed a unique urinary microbiota nondetectable by standard culture protocols. This systematic review summarizing recent data on the role of urinary microbiota in lower urinary tract (LUT) dysfunction supports urinary dysbiosis as a possible cause of different functional LUT disorders.