Urinary bacteria: some good, some bad and some of unknown significance

The last decade has seen a revolution in our understanding of the role bacteria in female bladder health. The analyses presented here (Price et al, BJOG 2019) both reiterate and develop upon some the most important findings in this emerging field of urinary microbiome research. The medical school teaching of the bladder as an entirely sterile organ in health has proven to be often but not invariably wrong (Wolfe et al, J Clin Microbiol 2012), and here the authors not only find that three quarters of continent adult women have bacterial colonization of the bladder identifiable either by an expanded low threshold urinary culture (103 CFU/mL), or by 16S rRNA gene sequencing, but that some urotypes dominated by microbiota previously regarded as clearly pathogenic are not associated with any evidence of clinical disorder.