Hypothesis / aims of study
Classical paradigm states that bladder is a sterile medium and that its invasion by pathogenic microbes leads to urinary tract infection (UTI). Faced with this paradigm, the concept of microbial dysbioses claims that lower urinary tract dysfunctions (LUTD) is frequently due to a disturbance of the normal urinary bacterial flora (1). Similarly there is a controversy about the relationship between pelvic organ prolapse (POP) and UTI.
The aims of our study are to assess if there are any relationship between female microbial urinary profile and LUTD and between female microbial urinary profile and POP
Study design, materials and methods
Cross sectional study
Materials and methods
We carried out a cross sectional study in a series of women who underwent a urodynamic study between April 2017 and March 2018. The inclusion criteria were age greater than 18 years and willingness to participate in this study. Exclusion criteria were pregnancy, previous pelvic surgery, active urinary tract infection, neurogenic lower urinary tract dysfunction, urinary catheterization and genitourinary neoplasms.
We enrolled 94 women, aged 36 ± 37.7 years (mean ± standard deviation). A midstream urine was collected, after the urethral area was washed with sterile water. All samples were routinely inoculated for 24 hours and in a prolonged way for 48 hours. After the sample collection, patients were fully investigated for the presence of lower urinary tract symptoms (LUTS) and submitted to a gynaecological exploration to check the presence and staging of POP. Finally in the same session, patients underwent a urodynamic study according to the specifications of ICS and guidelines of Good Urodynamic practices.
Sample size was calculated based on the data provided by Brubaker et al. (2), and Moore et al. (3). Assuming a prevalence of bladder bacterial DNA without UTI of 38.7 % and a difference on UTI prevalence of 10% between patients with and without detrusor overactivity, with an alpha level of 5%, and a statistical power of 80%, the minimum sample size was calculated at 40 patients per group.
For statistical analysis we used the Fisher exact text and the chi-square test for qualitative variables and the t-test to compare the means of parametric data. Quantitative data were tested for normal distribution using the Kolmogorov-Smirnov test. Statistical significance was set at P < 0.05.
Interpretation of results
The results of this study suggest a relationship between some LUTS and bacterial flora of the lower urinary tract. This relationship is different from the association between UTI and urgency or detrusor overactivity found in other reports, because in this study we excluded patients with active UTI and because we carried out an enhanced 48-hour urine culture that detects slow growing, anaerobic and fastidious bacteria. In this study we found that urgency was associated not only with the presence of fast-growing classical aerobic uropathogens such as Escherichia coli, but also with the presence of vaginal and cutaneous-mucosal flora like Lactobacillus or Corynebacterium gender. The absence of association between 48-hour urine culture and urodynamic findings also suggests that bacteria would only act on sensory receptors, rather than triggering detrusor overactivity. On the other hand the association of uropathogens with pelvic prolapses and vaginal and cutaneous-mucosal flora with absence or low POP stage raises the question that differences in resident bacteria in the adult bladder affect not only to lower urinary tract dysfunctions but also to anatomical abnormalities. Finally, it is worth noting the presence of emerging uropathogen like Alloscardovia omnicollens or Aerococcus urinae related to functional and anatomical disorders of the lower urinary tract and pelvic organ.