IN CELLULAR AND INFECTION MICROBIOLOGY The Human Urinary Microbiome; bacterial DNA in voided urine of asymptomatic adults

26 The urinary microbiome of healthy individuals and the way it alters with ageing have not 27 been characterised and may influence disease processes. Conventional microbiological 28 methods have limited scope to capture the full spectrum of urinary bacterial species. We 29 studied the urinary microbiota from a population of healthy individuals, ranging from 26 to 30 90 years of age, by amplification of the 16S rRNA gene, with resulting amplicons analysed 31 by 454 pyrosequencing. Mid-stream urine was collected by the ‘clean-catch’ method. 32 Quantitative PCR of 16S rRNA genes in urine samples, allowed relative enumeration of the 33 bacterial loads. Analysis of the samples indicates that females had a more heterogeneous mix 34 of bacterial genera compared to the male samples and generally had representative members 35 of the phyla Actinobacteria and Bacteroidetes. Analysis of the data leads us to conclude that 36 a ‘core’ urinary microbiome could potentially exist, when samples are grouped by age with 37 fluctuation in abundance between age groups. The study also revealed age-specific genera 38 Jonquetella, Parvimonas, Proteiniphilum and Saccharofermentans. In conclusion, 39 conventional microbiological methods are inadequate to fully identify around two-thirds of 40 the bacteria identified in this study. Whilst this proof-of-principle study has limitations due to 41 the sample size, the discoveries evident in this sample data are strongly suggestive that a 42 larger study on the urinary microbiome should be encouraged and that the identification of 43 specific genera at particular ages may be relevant to pathogenesis of clinical conditions. 44