The Vaginal Microbiota and Urinary Tract Infection

Abstract

The vagina is a key anatomical site in the pathogenesis of urinary tract infection (UTI) in women, serving as a potential reservoir for infecting bacteria and a site at which interventions may decrease the risk of UTI. The vaginal microbiota is a dynamic and often critical factor in this pathogenic interplay, because changes in the characteristics of the vaginal microbiota resulting in the loss of normally protective Lactobacillus spp. increase the risk of UTI. These alterations may result from the influence of estrogen deficiency, antimicrobial therapy, contraceptives, or other causes. Interventions to reduce adverse effects on the vaginal microbiota and/or to restore protective lactobacilli may reduce the risks of UTI. INTRODUCTION Urinary tract infections (UTIs) are a common clinical problem across the lifespan of women. Although UTIs are not systematically tracked, making estimates of U.S. incidence somewhat challenging, the most recent combined National Hospital Ambulatory Medical Care Survey and National Ambulatory Medical Care Survey data from 2009-2010 suggest that approximately 10 million outpatient visits for a diagnosis of UTI occur annually in the United States among both women and men (1). Women are disproportionately affected, with an estimated lifetime risk of UTI of 60% (2). In otherwise healthy, sexually active premenopausal women, these infections occur approximately every other year (3). As women age, UTIs become more common (2). A population-based study of community-onset UTI among nearly 31,000 residents of Calgary showed that the incidence of UTI among women demonstrates an initial peak in the twenties (30 per 1,000), decreases slightly during the later reproductive years, then steadily increases with every decade of life starting in late middle age, reaching a maximum of 125/1,000 at and above age 80 (4). Although the cost of treating UTI has not been recently estimated, the last published estimate in 2010 indicated that the annual U.S. domestic cost exceeded two billion dollars (5-7). Despite decades of studies defining the epidemiology, risk factors, and pathogenic mechanisms in UTIs, current evidence-based prevention strategies still rely upon the use of low-dose prophylactic antimicrobials as the cornerstone of prevention of recurrent UTIs in women of any age (8). For postmenopausal women, vaginal estrogen therapy may be considered, but this is often as an adjunctive to antimicrobial-based prophylaxis (8). Given

Applying concepts of life course theory and life course epidemiology to the study of bladder health and lower urinary tract symptoms among girls and women

“…Birth, infancy, early childhood, adolescence, sexual debut, pregnancy, menopause, and older age are periods during which girls and women may be more sensitive to the effects of antimicrobial exposure, due to age‐related physiological states of organ systems, as well as endogenous hormonal effects on the genitourinary tract 82 . For example, following menopause women experience a rise in vaginal pH and a decrease in protective Lactobacilli that normally inhabit the vagina, which, in turn, allows more pathologic organisms to colonize the vagina, potentially leading to urogenital infection 84 . Chains of risk are particularly relevant to antimicrobial exposure, as initial exposure to antimicrobial agents may alter host defenses, which, in turn, may lead to greater susceptibility to infection, additional antimicrobial exposure, and even further altered host defenses 82 .…”

“…Estrogen deficiency has been linked with LUTS, 89 potentially through a decline in lactobacillus or other alterations of the microbiome 84 . Exogenous hormone use may favorably influence pelvic floor function through improvement of pelvic muscle tissue quality (eg, ability to detect bladder sensations and apply urethral pressure) 90 .…”

Females with Impaired Ovarian Function Could Be Vulnerable to Environmental Pollutants: Identification via Next-Generation Sequencing of the Vaginal Microbiome

“…To our knowledge, this is the rst evaluation of this association using next-generation sequencing. Previous studies investigated the association of the vaginal microbiome with menopause (31), perinatal outcome (32), preterm birth (33), sexually transmitted diseases (34), vaginitis (30), HPV (35), and urinary tract infections (36). No study has evaluated the relationship of the vaginal microbiome with environmental pollutants in young females with impaired ovarian function.…”

The vaginal microbiome in uterine transplantation

“…Given that UTx is a fertility‐restoring procedure, and each case can only be deemed successful once it has yielded a livebirth, the VM deserves particular consideration in the context of UTx. Moreover, given the links between VM dysbiosis and infection, cervical intra‐epithelial neoplasia (CIN), and gynaecological cancer, which are all associated risks of UTx through the use of immunosuppression, the potential significance of the role of the VM in UTx intensifies further. Here we summarise the potential implications of the VM in the context of UTx and provide a framework for potential areas of future research.…”