Current and emerging strategies to curb antibiotic-resistant urinary tract infections

Rising rates of antibiotic resistance in uropathogenic bacteria compromise patient outcomes and prolong hospital stays. Consequently, new strategies are needed to prevent and control the spread of antibiotic resistance in uropathogenic bacteria. Over the past two decades, sizeable clinical efforts and research advances have changed urinary tract infection (UTI) treatment and prevention strategies to conserve antibiotic use. The emergence of antimicrobial stewardship, policies from national societies, and the development of new antimicrobials have shaped modern UTI practices. Future UTI management practices could be driven by the evolution of antimicrobial stewardship, improved and readily available diagnostics, and an improved understanding of how the microbiome affects UTI. Forthcoming UTI treatment and prevention strategies could employ novel bactericidal compounds, combinations of new and classic antimicrobials that enhance bacterial killing, medications that prevent bacterial attachment to uroepithelial cells, repurposing drugs, and vaccines to curtail the rising rates of antibiotic resistance in uropathogenic bacteria and improve outcomes in people with UTI.

Therapeutic strategies for uncomplicated cystitis in women

Uncomplicated cystitis is affecting many women of all ages and has a great impact on the quality of life, especially in women suffering from recurrent, uncomplicated cystitis. By far the most frequent uropathogen, E. coli, may have acquired increasing resistance against a variety of oral antibiotics, which may differ between countries and regions. Therefore, local resistance data are important to be considered. On the other hand, non-antibiotic therapy has also become an option which should be discussed and offered to the patient. In patients suffering from recurrent uncomplicated cystitis, individual risk factors and possible behavioral changes should first be taken into account. Non-antimicrobial prophylactic strategies shown to be successful in well-designed clinical studies are the next options. Long term antibiotic prophylaxis, however, should only be considered as a last option. For some of those patients self-diagnosis and self-treatment may be suitable, e.g. by using a recognized questionnaire.

17β-estradiol Attenuates the Middle Ear Inflammatory Response to Nontypeable Haemophilus influenzae

OBJECTIVES

17β-estradiol (E2) is a steroidal hormone with immunomodulatory functions that play a role in infectious and inflammatory diseases. E2 was recently identified as the leading upstream regulator of differentially expressed genes in a comparative RNA sequencing study of pediatric patients with otitis media (OM) versus OM-free counterparts and may therefore play a role in the inflammatory response to bacterial otopathogens during pediatric OM. This study examined the effect of E2 on bacterial-induced inflammatory cytokine expression in an in vitro pediatric OM model.

METHODS

An immortalized middle ear (ME) epithelial cell line, ROM-SV40, was developed from a pediatric recurrent OM patient. The culture was exposed to E2 at physiological levels for 1-48 h prior to 6 h-stimulation with nontypeable Haemophilus influenzae (NTHi) whole cell lysate. TNFA, IL1B, IL6, and IL8 were assayed by qPCR and ELISA.

RESULTS

E2 pretreatment (24 h) abrogated NTHi induction of IL6; a longer pretreatment (1-10 nM, 48 h) abrogated IL1B induction (p < 0.05). E2 pretreatment (5 nM, 48 h) abrogated NTHi-induced IL8 secretion (p = 0.017).

CONCLUSION

E2 pretreatment partially rescued NTHi-induced cytokine production by ME epithelia. These data support a role for E2 in moderating the excessive inflammatory response to middle ear infection that contributes to OM pathophysiology.

LEVELS OF EVIDENCE

NA Laryngoscope, 2024.

Ovarian sex steroid and epithelial control of immune responses in the uterus and oviduct: human and animal models†

The female reproductive tract (FRT), including the uterus and oviduct (Fallopian tube), is responsible for maintaining an optimal microenvironment for reproductive processes, such as gamete activation and transportation, sperm capacitation, fertilization, and early embryonic and fetal development. The mucosal surface of the FRT may be exposed to pathogens and sexually transmitted microorganisms due to the opening of the cervix during mating. Pathogens and endotoxins may also reach the oviduct through the peritoneal fluid. To maintain an optimum reproductive environment while recognizing and killing pathogenic bacterial and viral agents, the oviduct and uterus should be equipped with an efficient and rigorously controlled immune system. Ovarian sex steroids can affect epithelial cells and underlying stromal cells, which have been shown to mediate innate and adaptive immune responses. This, in turn, protects against potential infections while maintaining an optimal milieu for reproductive events, highlighting the homeostatic involvement of ovarian sex steroids and reproductive epithelial cells. This article will discuss how ovarian sex steroids affect the immune reactions elicited by the epithelial cells of the non-pregnant uterus and oviduct in the bovine, murine, and human species. Finally, we propose that there are regional and species-specific differences in the immune responses in FRT.

Uropathogen and host responses in pyelonephritis

Urinary tract infections (UTIs) are among the most common bacterial infections seen in clinical practice. The ascent of UTI-causing pathogens to the kidneys results in pyelonephritis, which can trigger kidney injury, scarring and ultimately impair kidney function. Despite sizable efforts to understand how infections develop or are cleared in the bladder, our appreciation of the mechanisms by which infections develop, progress or are eradicated in the kidney is limited. The identification of virulence factors that are produced by uropathogenic Escherichia coli to promote pyelonephritis have begun to fill this knowledge gap, as have insights into the mechanisms by which kidney tubular epithelial cells oppose uropathogenic E. coli infection to prevent or eradicate UTIs. Emerging data also illustrate how specific cellular immune responses eradicate infection whereas other immune cell populations promote kidney injury. Insights into the mechanisms by which uropathogenic E. coli circumvent host immune defences or antibiotic therapy to cause pyelonephritis is paramount to the development of new prevention and treatment strategies to mitigate pyelonephritis and its associated complications.

The Role of NLRP3 in Regulation of Antimicrobial Peptides and Estrogen Signaling in UPEC-Infected Bladder Epithelial Cells

The NLRP3 inflammasome, estrogen and antimicrobial peptides have all been found to have a vital role in the protection of the bladder urothelium. However, the interdependence between these protective factors during a bladder infection is currently unknown. Our aim was to investigate the role of NLRP3 in the regulation of antimicrobial peptides and estrogen signaling in bladder epithelial cells during a UPEC infection. Human bladder epithelial cells and CRISPR/Cas9-generated NLRP3-deficient cells were stimulated with the UPEC strain CFT073 and estradiol. The gene and protein expression were evaluated with microarray, qRT-PCR, western blot and ELISA. Microarray results showed that the expression of most antimicrobial peptides was reduced in CFT073-infected NLRP3-deficient cells compared to Cas9 control cells. Conditioned medium from NLRP3-deficient cells also lost the ability to suppress CFT073 growth. Moreover, NLRP3-deficient cells had lower basal release of Beta-defensin-1, Beta-defensin-2 and RNase7. The ability of estradiol to induce an increased expression of antimicrobial peptides was also abrogated in NLRP3-deficient cells. The decreased antimicrobial peptide expression might be linked to the observed reduced expression and activity of estradiol receptor beta in NLRP3-deficient cells. This study suggests that NLRP3 may regulate the release and expression of antimicrobial peptides and affect estrogen signaling in bladder epithelial cells.

Therapeutic Effects of Vitamin D on Vaginal, Sexual, and Urological Functions in Postmenopausal Women

Recent years have witnessed the emergence of growing evidence concerning vitamin D's potential role in women's health, specifically in postmenopausal women. This evidence also includes its connection to various genitourinary disorders and symptoms. Numerous clinical studies have observed improvements in vulvovaginal symptoms linked to the genitourinary syndrome of menopause (GSM) with vitamin D supplementation. These studies have reported positive effects on various aspects, such as vaginal pH, dryness, sexual functioning, reduced libido, and decreased urinary tract infections. Many mechanisms underlying these pharmacological effects have since been proposed. Vitamin D receptors (VDRs) have been identified as a major contributor to its effects. It is now well known that VDRs are expressed in the superficial layers of the urogenital organs. Additionally, vitamin D plays a crucial role in supporting immune function and modulating the body's defense mechanisms. However, the characterization of these effects requires more investigation. Reviewing existing evidence regarding vitamin D's impact on postmenopausal women's vaginal, sexual, and urological health is the purpose of this article. As research in this area continues, there is a potential for vitamin D to support women's urogenital and sexual health during the menopausal transition and postmenopausal periods.

Urologic view in the management of genitourinary syndrome of menopause

Genitourinary syndrome of menopause (GSM) has a variety of effects on the urinary system and is an important consideration in the care provided to perimenopausal and postmenopausal patients when addressing urinary pathology. Here we discuss the common pathologies of the urinary system related to GSM including lower urinary tract symptoms and recurrent urinary tract infections. Female sexual dysfunction is not to be excluded as a critical part of a urologist's management of GSM but will be discussed elsewhere in this issue.

Supraphysiologic Vaginal Estrogen Therapy in Aged Mice Mitigates Age-Associated Bladder Inflammatory Response to Urinary Tract Infections

IMPORTANCE

Bladder diseases characterized by chronic inflammation are highly prevalent in older women, as are recurrent urinary tract infections (rUTIs). Recurrent urinary tract infections lead to chronic inflammation of the bladder mucosa and cause lower urinary tract symptoms that persist even after the infection is cleared. Vaginal estrogen therapy (VET) has long been used for the treatment of rUTIs; however, its mechanism of action remains unclear.

OBJECTIVES

The objective of this study was to examine the mechanism(s) by which VET affects bladder inflammation and response to rUTIs.

STUDY DESIGN

Here, we induced surgical menopause in aged (18 months old) mice followed by VET. Mice were then infected with uropathogenic Escherichia coli , and course of infection was investigated. Inflammatory cytokine response was assessed before and during infection using enzyme-linked immunosorbent assay. RNA sequencing analysis was used to compare the inflammatory status of the young versus aged bladder and principal changes confirmed via quantitative reverse transcriptase-polymerase chain reaction to determine the effects of VET on bladder inflammation. Impact on age-associated bladder tertiary lymphoid tissue formation was evaluated histologically.

RESULTS

In the ovariectomized aged model, VET not only mitigated uterine atrophy but was also associated with reduced rUTIs, number of bacterial reservoirs, dampened immune response, and promotion of terminal differentiation of urothelial cells. Bladder tertiary lymphoid tissue lesions were also reduced with VET, with an associated decrease in signals important for bladder tertiary lymphoid tissue formation. Finally, we determined that VET reverses age-associated upregulation of inflammatory genes and pathways.

CONCLUSIONS

Our data suggest that VET is effective by reducing age-associated hyperinflammatory conditions in bladder mucosa and in enhancing the host response to infection.

Effects of aging on urinary tract epithelial homeostasis and immunity

A global increase in older individuals creates an increasing demand to understand numerous healthcare challenges related to aging. This population is subject to changes in tissue physiology and the immune response network. Older individuals are particularly susceptible to infectious diseases, with one of the most common being urinary tract infections (UTIs). Postmenopausal and older women have the highest risk of recurrent UTIs (rUTIs); however, why rUTIs become more frequent after menopause and during old age is incompletely understood. This increased susceptibility and severity among older individuals may involve functional changes to the immune system with age. Aging also has substantial effects on the epithelium and the immune system that led to impaired protection against pathogens, yet heightened and prolonged inflammation. How the immune system and its responses to infection changes within the bladder mucosa during aging has largely remained poorly understood. In this review, we highlight our understanding of bladder innate and adaptive immunity and the impact of aging and hormones and hormone therapy on bladder epithelial homeostasis and immunity. In particular, we elaborate on how the cellular and molecular immune landscape within the bladder can be altered during aging as aged mice develop bladder tertiary lymphoid tissues (bTLT), which are absent in young mice leading to profound age-associated change to the immune landscape in bladders that might drive the significant increase in UTI susceptibility. Knowledge of host factors that prevent or promote infection can lead to targeted treatment and prevention regimens. This review also identifies unique host factors to consider in the older, female host for improving rUTI treatment and prevention by dissecting the age-associated alteration of the bladder mucosal immune system.

17β-estradiol ameliorates delirium-like phenotypes in a murine model of urinary tract infection

Urinary tract infections (UTIs) are common and frequently precipitate delirium-like states. Advanced age coincident with the postmenopausal period is a risk factor for delirium following UTIs. We previously demonstrated a pathological role for interleukin-6 (IL-6) in mediating delirium-like phenotypes in a murine model of UTI. Estrogen has been implicated in reducing peripheral IL-6 expression, but it is unknown whether the increased susceptibility of postmenopausal females to developing delirium concomitant with UTIs reflects diminished effects of circulating estrogen. Here, we tested this hypothesis in a mouse model of UTI. Female C57BL/6J mice were oophorectomized, UTIs induced by transurethral inoculation of E. coli, and treated with 17β-estradiol. Delirium-like behaviors were evaluated prior to and following UTI and 17β-estradiol treatment. Compared to controls, mice treated with 17β-estradiol had less neuronal injury, improved delirium-like behaviors, and less plasma and frontal cortex IL-6. In vitro studies further showed that 17β-estradiol may also directly mediate neuronal protection, suggesting pleiotropic mechanisms of 17β-estradiol-mediated neuroprotection. In summary, we demonstrate a beneficial role for 17β-estradiol in ameliorating acute UTI-induced structural and functional delirium-like phenotypes. These findings provide pre-clinical justification for 17β-estradiol as a therapeutic target to ameliorate delirium following UTI.

Diabetes downregulates the antimicrobial peptide psoriasin and increases E. coli burden in the urinary bladder

Diabetes is known to increase susceptibility to infections, partly due to impaired granulocyte function and changes in the innate immunity. Here, we investigate the effect of diabetes, and high glucose on the expression of the antimicrobial peptide, psoriasin and the putative consequences for E. coli urinary tract infection. Blood, urine, and urine exfoliated cells from patients are studied. The influence of glucose and insulin is examined during hyperglycemic clamps in individuals with prediabetes and in euglycemic hyperinsulinemic clamped patients with type 1 diabetes. Important findings are confirmed in vivo in type 2 diabetic mice and verified in human uroepithelial cell lines. High glucose concentrations induce lower psoriasin levels and impair epithelial barrier function together with altering cell membrane proteins and cytoskeletal elements, resulting in increasing bacterial burden. Estradiol treatment restores the cellular function with increasing psoriasin and bacterial killing in uroepithelial cells, confirming its importance during urinary tract infection in hyperglycemia. In conclusion, our findings present the effects and underlying mechanisms of high glucose compromising innate immunity.

A stable cyclized antimicrobial peptide derived from LL-37 with host immunomodulatory effects and activity against uropathogens

The increasing antibiotic resistance among uropathogenic bacteria warrants alternative therapeutic strategies. We demonstrate the potential of the synthetic peptide CD4-PP, designed by dimerization and backbone cyclization of the shortest antimicrobial region of human cathelicidin, LL-37. CD4-PP is active against clinical and type strains of common uropathogens Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa at concentrations substantially below cellular cytotoxic levels and induced membrane deformation and leakage in E. coli and P. aeruginosa. Furthermore, CD4-PP treatment prevented the formation of new biofilm and dissolved mature biofilm created by E. coli and P. aeruginosa and targeted curli amyloid in E. coli biofilms. In addition, CD4-PP also induced production of LL-37 by uroepithelial cells and increased the expression of tight junction proteins claudin-14 and occludin. During uroepithelial cell infection, CD4-PP significantly reduced uropathogen survival when treatment was given at the start of infection. Low micromolar of CD4-PP treatment initiated after 2 h was successful with all tested species, except P. aeruginosa where CD4-PP was unable to reduce survival, which could be attributed by early biofilm formation. Finally, we demonstrated that urinary catheter pieces coated with saline fluid supplemented with CD4-PP reduced the attachment of E. coli, giving it a potential clinical application.

Vaginal Inoculation of Uropathogenic Escherichia coli during Estrus Leads to Genital and Renal Colonization

Urinary tract infection (UTI) is one of the most prevalent bacterial infections, particularly in women, children, and the elderly. Uropathogenic Escherichia coli (UPEC) is the predominant etiological agent of UTI. Uropathogens are directly instilled in the urinary bladder, bypassing the lower urogenital tract, in the widely used murine model of UTI. We assessed whether vaginal inoculation of UPEC led to UTI and how stages of the estrous cycle would impact bacterial colonization in mice. Mice in proestrus, estrus, metestrus, and diestrus were identified by vaginal cytology and inoculated with UPEC in the vaginal tract. Mice were euthanized 1 day after infection, and bacterial loads in the urogenital tract, liver, and spleen were enumerated. Mice in estrus exhibited the highest and most consistent UPEC burdens in all organs, except the bladder. Vaginal inoculation resulted in bladder colonization in a UPEC strain-specific manner. In contrast, transurethral inoculation of UPEC led to bladder colonization. Importantly, inoculation by both routes led to vaginal and uterine colonization and concomitant systemic dissemination to the spleen and liver. The kinetics of bacterial colonization over 2 weeks following vaginal inoculation was comparable in the urogenital tract. Tissue sections revealed the induction of vaginitis and cystitis upon the vaginal instillation of UPEC. In summary, vaginal inoculation of UPEC in mice during estrus represents a novel approach to investigate infection of the kidneys and genital tract and systemic dissemination from the urogenital tract. Our findings suggest that estrogen primes the urogenital tract to create a conducive milieu for UPEC colonization.

Urine Flow Cytometry Parameter Cannot Safely Predict Contamination of Urine—A Cohort Study of a Swiss Emergency Department Using Machine Learning Techniques

Background: Urine flow cytometry (UFC) analyses urine samples and determines parameter counts. We aimed to predict different types of urine culture growth, including mixed growth indicating urine culture contamination. Methods: A retrospective cohort study (07/2017–09/2020) was performed on pairs of urine samples and urine cultures obtained from adult emergency department patients. The dataset was split into a training (75%) and validation set (25%). Statistical analysis was performed using a machine learning approach with extreme gradient boosting to predict urine culture growth types (i.e., negative, positive, and mixed) using UFC parameters obtained by UF-4000, sex, and age. Results: In total, 3835 urine samples were included. Detection of squamous epithelial cells, bacteria, and leukocytes by UFC were associated with the different types of culture growth. We achieved a prediction accuracy of 80% in the three-class approach. Of the n = 126 mixed cultures in the validation set, 11.1% were correctly predicted; positive and negative cultures were correctly predicted in 74.0% and 96.3%. Conclusions: Significant bacterial growth can be safely ruled out using UFC parameters. However, positive urine culture growth (rule in) or even mixed culture growth (suggesting contamination) cannot be adequately predicted using UFC parameters alone. Squamous epithelial cells are associated with mixed culture growth.

Psychosocial burden of recurrent uncomplicated urinary tract infections

Introduction: Urinary tract infections (UTI) are a leading cause of bacterial infections in women. Despite acute treatment, 30-50% of women who have a UTI will experience a recurrence within 6-12 months. In this review, the focus will be on the personal psychosocial impacts of recurrent UTI. Methods: A PubMed/MEDLINE literature search was carried out from 2000 to 2020 in order to identify any recent high-quality meta-analyses or systematic reviews on these topics. Results: One systematic review was found appropriate for this manuscript. Concerning impact on quality of life (QoL) and daily activities, a reduced quality of both intimate and social relationships, self-esteem, and capacity for work was found due to recurrent UTI. Social function was substantially more reduced than physical function. In one study, the greatest reduction overall was in mental role functioning, whereas in another study, mental health reductions were not substantially greater than those of physical health. About one third of women suffered from UTI very often or often after sexual intercourse, and more than half of the patients stated that sexual relations were negatively influenced by UTI. Data from the GESPRIT study suggest that prophylaxis for recurrent UTI is underutilized, because less than 40% of the study population were offered prophylaxis after experiencing three UTI per year, despite all surveyed participants being willing to undertake at least one of the prophylactic measures listed in the survey. Conclusions: Little data on the psychosocial impact of recurrent UTI are available. Therefore, future studies must also incorporate QoL assessments as key outcome measures.

Uncovering a Hub Signaling Pathway of Antimicrobial-Antifungal-Anticancer Peptides’ Axis on Short Cationic Peptides via Network Pharmacology Study

Short cationic peptides (SCPs) with therapeutic efficacy of antimicrobial peptides (AMPs), antifungal peptides (AFPs), and anticancer peptides (ACPs) are known as an enhancement of the host defense system. Here, we investigated the uppermost peptide(s), hub signaling pathway(s), and their associated target(s) through network pharmacology. Firstly, we selected SCPs with positive amino acid residues on N- and C- terminals under 500 Dalton via RStudio. Secondly, the overlapping targets between the bacteria-responsive targets (TTD and OMIM) and AMPs’ targets were visualized by VENNY 2.1. Thirdly, the overlapping targets between AFPs’ targets and fungal-responsive targets were exhibited by VENNY 2.1. Fourthly, the overlapping targets between cancer-related targets (TTD and OMIM) and fungal-responsive targets were displayed by VENNY 2.1. Finally, a molecular docking study (MDS) was carried out to discover the most potent peptides on a hub signaling pathway. A total of 1833 SCPs were identified, and AMPs’, AFPs’, and ACPs’ filtration suggested that 197 peptides (30 targets), 81 peptides (6 targets), and 59 peptides (4 targets) were connected, respectively. The AMPs―AFPs―ACPs’ axis indicated that 27 peptides (2 targets) were associated. Each hub signaling pathway for the enhancement of the host defense system was “Inactivation of Rap1 signaling pathway on AMPs”, “Activation of Notch signaling pathway on AMPs―AFPs’ axis”, and “Inactivation of HIF-1 signaling pathway on AMPs―AFPs―ACPs’ axis”. The most potent peptides were assessed via MDS; finally, HPIK on STAT3 and HVTK on NOS2 and on HIF-1 signaling pathway were the most stable complexes. Furthermore, the two peptides had better affinity scores than standard inhibitors (Stattic, 1400 W). Overall, the most potent SCPs for the human defense system were HPIK on STAT3 and HVTK on NOS2, which might inactivate the HIF-1 signaling pathway.

The impact of biological sex on diseases of the urinary tract

Biological sex, being female or male, broadly influences diverse immune phenotypes, including immune responses to diseases at mucosal surfaces. Sex hormones, sex chromosomes, sexual dimorphism, and gender differences all contribute to how an organism will respond to diseases of the urinary tract, such as bladder infection or cancer. Although the incidence of urinary tract infection is strongly sex biased, rates of infection change over a lifetime in women and men, suggesting that accompanying changes in the levels of sex hormones may play a role in the response to infection. Bladder cancer is also sex biased in that 75% of newly diagnosed patients are men. Bladder cancer development is shaped by contributions from both sex hormones and sex chromosomes, demonstrating that the influence of sex on disease can be complex. With a better understanding of how sex influences disease and immunity, we can envision sex-specific therapies to better treat diseases of the urinary tract and potentially diseases of other mucosal tissues.

Analysis of recurrent urinary tract infection management in women seen in outpatient settings reveals opportunities for antibiotic stewardship interventions

Objectives:

We characterized antibiotic prescribing patterns and management practices among recurrent urinary tract infection (rUTI) patients, and we identified factors associated with lack of guideline adherence to antibiotic choice, duration of treatment, and urine cultures obtained. We hypothesized that prior resistance to nitrofurantoin or trimethoprim–sulfamethoxazole (TMP-SMX), shorter intervals between rUTIs, and more frequent rUTIs would be associated with fluoroquinolone or β-lactam prescribing, or longer duration of therapy.

Methods:

This study was a retrospective database study of adult women with International Classification of Diseases, Tenth Revision (ICD-10) cystitis codes meeting American Urological Association rUTI criteria at outpatient clinics within our academic medical center between 2016 and 2018. We excluded patients with ICD-10 codes indicative of complicated UTI or pyelonephritis. Generalized estimating equations were used for risk-factor analysis.

Results:

Among 214 patients with 566 visits, 61.5% of prescriptions comprised first-line agents of nitrofurantoin (39.7%) and TMP-SMX (21.5%), followed by second-line choices of fluoroquinolones (27.2%) and β-lactams (11%). Most fluoroquinolone prescriptions (86.7%), TMP-SMX prescriptions (72.2%), and nitrofurantoin prescriptions (60.2%) exceeded the guideline-recommended duration. Approximately half of visits lacked a urine culture. Receiving care through urology via telephone was associated with receiving a β-lactam (adjusted odds ratio [aOR], 6.34; 95% confidence interval [CI], 2.58–15.56) or fluoroquinolone (OR, 2.28; 95% CI, 1.07–4.86). Having >2 rUTIs during the study period and seeking care from a urology practice (RR, 1.28, 95% CI, 1.15–1.44) were associated with longer antibiotic duration.

Conclusions:

We found low guideline concordance for antibiotic choice, duration of therapy and cultures obtained among rUTI patients. These factors represent new targets for outpatient antibiotic stewardship interventions.

Recurrent Urinary Tract Infections and Asymptomatic Bacteriuria in Adults

Purpose of review

Our goal was to summarize recent evidence regarding recurrent urinary tract infections and asymptomatic bacteriuria in different adult populations.

Recent findings

Several research groups are focused on the description of resident bacterial flora in the bladder and urinary dysbiosis in the microbiome era. Even the definitions might change in light of these discoveries. However, the role of urinary microbiome and bacterial interference has still to be determined.

Summary

Systematic treatment of asymptomatic bacteriuria is not recommended and even classic indications such as asymptomatic bacteriuria in pregnant women are controversial. In fact, its treatment is associated with a higher probability of symptomatic UTI and a higher prevalence of antibiotic-resistant bacteria. Improving the diagnosis of asymptomatic bacteriuria and optimizing the management of recurrent urinary tract infections, especially through non-antibiotics measures, are needed in order to minimise antimicrobial resistance.

HIF-1 mediated activation of antimicrobial peptide LL-37 in type 2 diabetic patients

Abstract

Infections are common in patients with diabetes, but increasing antibiotic resistance hampers successful bacterial clearance and calls for alternative treatment strategies. Hypoxia-inducible factor 1 (HIF-1) is known to influence the innate immune defense and could therefore serve as a possible target. However, the impact of high glucose on HIF-1 has received little attention and merits closer investigation. Here, we show that higher levels of proinflammatory cytokines and CAMP, encoding for the antimicrobial peptide cathelicidin, LL-37, correlate with HIF-1 in type 2 diabetic patients. Chemical activation of HIF-1 further enhanced LL-37, IL-1β, and IL-8 in human uroepithelial cells exposed to high glucose. Moreover, HIF-1 activation of transurethrally infected diabetic mice resulted in lower bacterial load. Drugs activating HIF-1 could therefore in the future potentially have a therapeutic role in clearing bacteria in diabetic patients with infections where antibiotic treatment failed.

Key messages

• Mohanty et al. “HIF-1 mediated activation of antimicrobial peptide LL-37 in type 2 diabetic patients.”

• Our study highlights induction of the antimicrobial peptide, LL-37, and strengthening of the innate immunity through hypoxia-inducible factor 1 (HIF-1) in diabetes.

• Our key observations are:

1. HIF-1 activation increased LL-37 expression in human urothelial cells treated with high glucose. In line with that, we demonstrated that patients with type 2 diabetes living at high altitude had increased levels of the LL-37.

2. HIF-1 activation increased IL-1β and IL-8 in human uroepithelial cells treated with high glucose concentration.

3. Pharmacological activation of HIF-1 decreased bacterial load in the urinary bladder of mice with hereditary diabetes.

• We conclude that enhancing HIF-1 may along with antibiotics in the future contribute to the treatment in selected patient groups where traditional therapy is not possible.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00109-021-02134-7.

The Microbiome’s Function in Disorders of the Urinary Bladder

The introduction of next generation sequencing techniques has enabled the characterization of the urinary tract microbiome, which resulted in the rejection of the long-held notion of urinary bladder sterility. Since the discovery and confirmation of the human bladder microbiome, an increasing number of studies have defined this microbial community and understand better its relationship to urinary pathologies. The composition of microbial communities in the urinary tract is linked to a variety of urinary diseases. The purpose of this review is to provide an overview of current information about the urinary microbiome and diseases as well as the development of novel treatment methods.

Metformin strengthens uroepithelial immunity against E. coli infection

Urinary tract infection frequently caused by E. coli is one of the most common bacterial infections. Increasing antibiotic resistance jeopardizes successful treatment and alternative treatment strategies are therefore mandatory. Metformin, an oral antidiabetic drug, has been shown to activate macrophages in the protection against certain infecting microorganisms. Since epithelial cells often form the first line of defense, we here investigated the effect on uroepithelial cells during E. coli infection. Metformin upregulated the human antimicrobial peptides cathelicidin LL-37 and RNase7 via modulation of the TRPA1 channel and AMPK pathway. Interestingly, metformin stimulation enriched both LL-37 and TRPA1 in lysosomes. In addition, metformin specifically increased nitric oxide and mitochondrial, but not cytosolic ROS. Moreover, metformin also triggered mRNA expression of the proinflammatory cytokines IL1B, CXCL8 and growth factor GDF15 in human uroepithelial cells. The GDF15 peptide stimulated macrophages increased LL-37 expression, with increased bacterial killing. In conclusion, metformin stimulation strengthened the innate immunity of uroepithelial cells inducing enhanced extracellular and intracellular bacterial killing suggesting a favorable role of metformin in the host defense.

Recurrent Urinary Tract Infections: Unraveling the Complicated Environment of Uncomplicated rUTIs

Urinary tract infections (UTIs) are frequent in humans, affecting the upper and lower urinary tract. Present diagnosis relies on the positive culture of uropathogenic bacteria from urine and clinical markers of inflammation of the urinary tract. The bladder is constantly challenged by adverse environmental stimuli which influence urinary tract physiology, contributing to a dysbiotic environment. Simultaneously, pathogens are primed by environmental stressors such as antibiotics, favoring recurrent UTIs (rUTIs), resulting in chronic illness. Due to different confounders for UTI onset, a greater understanding of the fundamental environmental mechanisms and microbial ecology of the human urinary tract is required. Such advancements could promote the tandem translation of bench and computational studies for precision treatments and clinical management of UTIs. Therefore, there is an urgent need to understand the ecological interactions of the human urogenital microbial communities which precede rUTIs. This review aims to outline the mechanistic aspects of rUTI ecology underlying dysbiosis between both the human microbiome and host physiology which predisposes humans to rUTIs. By assessing the applications of next generation and systems level methods, we also recommend novel approaches to elucidate the systemic consequences of rUTIs which requires an integrated approach for successful treatment. To this end, we will provide an outlook towards the so-called 'uncomplicated environment of UTIs', a holistic and systems view that applies ecological principles to define patient-specific UTIs. This perspective illustrates the need to withdraw from traditional reductionist perspectives in infection biology and instead, a move towards a systems-view revolving around patient-specific pathophysiology during UTIs.

Estradiol Alters the Virulence Traits of Uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) is the most common bacteria to cause urinary tract infection (UTI). Postmenopausal women have an increased risk of recurrent UTI. This is partly explained by estrogenic effects on host defenses against UTI. Current research is mostly focused on how UPEC affects host factors, but not so much is known about how host factors like hormones affect UPEC virulence. The aim of the present study was to investigate the impact of estradiol exposure on the virulence of UPEC. We found that a postmenopausal concentration of estradiol increased CFT073 growth and biofilm formation, but not the premenopausal concentrations. Real-time qPCR showed that estradiol altered the expression of genes associated with the iron acquisition system and metabolic pathways in CFT073. We also found that estradiol in a dose-dependent manner increased the expression of fimH and papC adhesins and increased colonization and invasion of bladder epithelial cells. The premenopausal concentration of estradiol also suppressed cytokine release from bladder epithelial cells. Additionally, we also showed using a Caenorhabditis elegans killing assay that estradiol increased the survival of CFT073-infected C. elegans worms. Taken together, our findings show that estradiol has the ability to alter the virulence traits of UPEC.

Recurrent uncomplicated urinary tract infections: definitions and risk factors

Introduction: Recurrent uncomplicated urinary tract infections (UTI) have a high impact on patients’ quality of life and high direct and indirect costs for public health. Therefore, optimal management should be of high priority.

Methods: Current international guidelines were reviewed, and a systematic literature search was performed in Medline, Cochrane, and Embase.

Results: Several risks factors have been identified and used in everyday clinical practice to plan the correct strategy for recurrence prevention. Among all factors, the most important are: sexual intercourse, spermicide use, having a new sex partner, having a mother with a history of UTI, having had UTI during childhood, and asymptomatic bacteriuria treatment. Moreover, other risk factors such as reduced fluid intake, habitual and post-coital delayed urination, wiping from back to front after defecation, douching and wearing occlusive underwear, as well as irregular bowel function should be taken into account.

Conclusions: Recurrent UTI show a high impact on clinical practice. Risk factors are generally related to both virulence of pathogens and patient’s behavior or condition. A recently developed nomogram can assist in identifying women at high risk of symptomatic recurrence that can be suitable candidates for a prophylactic strategy.

Protective effect of oral contraceptive against Helicobacter pylori infection in US adult females: NHANES 1999-2000

Recently, the antibacterial properties of oestrogen and progestogen were discovered. The aim of this study was to find the cross-sectional association between oral contraceptive use and Helicobacter pylori seroprevalence. Data were obtained from the US National Health and Nutrition Examination Survey (NHANES). The H. pylori immunoglobulin G (IgG) enzyme-linked immunosorbent assays were used to categorise participants as seropositive or seronegative. The study population included 799 female participants who had information on H. pylori seroprevalence and all other covariates and had not been taking any medications (except oral contraceptives). The bivariate Rao–Scott chi-square test indicated a significant association between H. pylori seroprevalence and contraceptive use (P < 0.01). The variables of race, education, poverty income ratio, smoking, and blood lead and cadmium levels were also significantly associated with H. pylori seroprevalence (P < 0.01). Multiple logistic regression analysis of the age-adjusted model revealed that contraceptive users are 65% less likely of being H. pylori seropositive as compared to non-contraceptive users (odds ratio (OR): 0.35, 95% confidence interval (CI): 0.18–0.68). This association is stronger with the final multivariate model (OR: 0.46, 95% CI: 0.23–0.89). Conclusions: This finding reveals the potential protective effect of oral contraceptives against H. pylori infection and serves as a foundation study for further investigations.

Sex effects in pyelonephritis

Urinary tract infections (UTIs) are generally considered a disease of women. However, UTIs affect females throughout the lifespan, and certain male populations (including infants and elderly men) are also susceptible. Epidemiologically, pyelonephritis is more common in women but carries increased morbidity when it does occur in men. Among children, high-grade vesicoureteral reflux is a primary risk factor for upper-tract UTI in both sexes. However, among young infants with UTI, girls are outnumbered by boys; risk factors include posterior urethral valves and lack of circumcision. Recent advances in mouse models of UTI reveal sex differences in innate responses to UTI, which vary somewhat depending on the system used. Moreover, male mice and androgenized female mice suffer worse outcomes in experimental pyelonephritis; evidence suggests that androgen exposure may suppress innate control of infection in the urinary tract, but additional androgen effects, as well as non-hormonal sex effects, may yet be specified. Among other intriguing directions, recent experiments raise the hypothesis that the postnatal testosterone surge that occurs in male infants may represent an additional factor driving the higher incidence of UTI in males under 6 months of age. Ongoing work in contemporary models will further illuminate sex- and sex-hormone-specific effects on UTI pathogenesis and immune responses.

Estrogen receptors in human bladder cells regulate innate cytokine responses to differentially modulate uropathogenic E. coli colonization

The bladder epithelial cells elicit robust innate immune responses against urinary tract infections (UTIs) for preventing the bacterial colonization. Physiological fluctuations in circulating estrogen levels in women increase the susceptibility to UTI pathogenesis, often resulting in adverse health outcomes. Dr adhesin bearing Escherichia coli (Dr E. coli) cause recurrent UTIs in menopausal women and acute pyelonephritis in pregnant women. Dr E. coli bind to epithelial cells via host innate immune receptor CD55, under hormonal influence. The role of estrogens or estrogen receptors (ERs) in regulating the innate immune responses in the bladder are poorly understood. In the current study, we investigated the role of ERα, ERβ and GPR30 in modulating the innate immune responses against Dr E. coli induced UTI using human bladder epithelial carcinoma 5637 cells (HBEC). Both ERα and ERβ agonist treatment in bladder cells induced a protection against Dr E. coli invasion via upregulation of TNFα and downregulation of CD55 and IL10, and these effects were reversed by action of ERα and ERβ antagoinsts. In contrast, the agonist-mediated activation of GPR30 led to an increased bacterial colonization due to suppression of innate immune factors in the bladder cells, and these effects were reversed by the antagonist-mediated suppression of GPR30. Further, siRNA-mediated ERα knockdown in the bladder cells reversed the protection against bacterial invasion observed in the ERα positive bladder cells, by modulating the gene expression of TNFα, CD55 and IL10, thus confirming the protective role of ERα. We demonstrate for the first time a protective role of nuclear ERs, ERα and ERβ but not of membrane ER, GPR30 against Dr E. coli invasion in HBEC 5637 cells. These findings have many clinical implications and suggest that ERs may serve as potential drug targets towards developing novel therapeutics for regulating local innate immunity and treating UTIs.

Vaginal estrogen therapy is associated with increased Lactobacillus in the urine of postmenopausal women with overactive bladder symptoms

BACKGROUND

Previous work has shown that the vaginal microbiome decreases in Lactobacillus predominance and becomes more diverse after menopause. It has also been shown that estrogen therapy restores Lactobacillus dominance in the vagina and that topical estrogen is associated with overactive bladder symptom improvement. We now know that the bladder contains a unique microbiome and that increased bladder microbiome diversity is associated with overactive bladder. However, there is no understanding of how quickly each pelvic floor microbiome responds to estrogen or if those changes are associated with symptom improvement.

OBJECTIVE

This study aimed to determine if estrogen treatment of postmenopausal women with overactive bladder decreases urobiome diversity.

STUDY DESIGN

We analyzed data from postmenopausal participants in 2 trials (NCT02524769 and NCT02835846) who chose vaginal estrogen as the primary overactive bladder treatment and used 0.5 g of conjugated estrogen (Premarin cream; Pfizer, New York City, NY) twice weekly for 12 weeks. Baseline and 12-week follow-up data included the Overactive Bladder questionnaire, and participants provided urine samples via catheter, vaginal swabs, perineal swabs, and voided urine samples. Microbes were detected by an enhanced culture protocol. Linear mixed models were used to estimate microbiome changes over time. Urinary antimicrobial peptide activity was assessed by a bacterial growth inhibition assay and correlated with relative abundance of members of the urobiome.

RESULTS

In this study, 12 weeks of estrogen treatment resulted in decreased microbial diversity within the vagina (Shannon, P=.047; Richness, P=.043) but not in the other niches. A significant increase in Lactobacillus was detected in the bladder (P=.037) but not in the vagina (P=.33), perineum (P=.56), or voided urine (P=.28). The change in Lactobacillus levels in the bladder was associated with modest changes in urgency incontinence symptoms (P=.02). The relative abundance of the genus Corynebacterium correlated positively with urinary antimicrobial peptide activity after estrogen treatment.

CONCLUSION

Estrogen therapy may change the microbiome of different pelvic floor niches. The vagina begins to decrease in diversity, and the bladder experiences a significant increase in Lactobacillus levels; the latter is correlated with a modest improvement in the symptom severity subscale of the Overactive Bladder questionnaire.

The immune response to infection in the bladder

The bladder is continuously protected by passive defences such as a mucus layer, antimicrobial peptides and secretory immunoglobulins; however, these defences are occasionally overcome by invading bacteria that can induce a strong host inflammatory response in the bladder. The urothelium and resident immune cells produce additional defence molecules, cytokines and chemokines, which recruit inflammatory cells to the infected tissue. Resident and recruited immune cells act together to eradicate bacteria from the bladder and to develop lasting immune memory against infection. However, urinary tract infection (UTI) is commonly recurrent, suggesting that the induction of a memory response in the bladder is inadequate to prevent reinfection. Additionally, infection seems to induce long-lasting changes in the urothelium, which can render the tissue more susceptible to future infection. The innate immune response is well-studied in the field of UTI, but considerably less is known about how adaptive immunity develops and how repair mechanisms restore bladder homeostasis following infection. Furthermore, data demonstrate that sex-based differences in immunity affect resolution and infection can lead to tissue remodelling in the bladder following resolution of UTI. To combat the rise in antimicrobial resistance, innovative therapeutic approaches to bladder infection are currently in development. Improving our understanding of how the bladder responds to infection will support the development of improved treatments for UTI, particularly for those at risk of recurrent infection.

Vaginal Estrogen-What a Urologist Should Know

The implications of estrogen depletion on the lower urinary tract and vagina are relevant to the urologist treating women with genitourinary symptoms. The main symptoms of vaginal estrogen depletion that affect women are dyspareunia and vaginal dryness, recurrent urinary tract infection, and lower urinary tract symptoms. Vaginal estrogen can be used to effectively treat these conditions. Vaginal estrogen is available in a variety of formulations. Each formulation has different considerations regarding its use and patients should be actively involved in choosing the right product for them. Contrary to concerns over the risks of oral estrogen, vaginal estrogen has a low-risk profile. In terms of contra-indications for use, there are relatively few absolute contraindications for vaginal estrogen. A thorough understanding of vaginal estrogen's safety, efficacy and correct use is essential to the urologist treating the post-menopausal female.

Topical Estrogen Treatment Augments the Vaginal Response to Escherichia coli Flagellin

The female climacteric or menopausal process characterised by reduced estrogen, associates with an increased risk of recurrent urinary tract infections (rUTIs) linked to uropathogenic Escherichia coli (UPEC). Clinically, topical vaginal estrogen treatment has a prophylactic effect against such infections. The aim of this study was to investigate, in vitro, the effects of a topical estrogen treatment on vaginal epithelial responses following challenge with E.coli flagellin mimicking an UPEC challenge. Immortalised vaginal epithelial cells (VK2 E6/E7), modelling the vaginal epithelium were treated with either 4 nM 17β-estradiol (E) for seven days, 50 ng/ml E.coli flagellin (F) for 12 h, or 4 nM 17β-estradiol plus 50 ng/ml flagellin (E + F(12 h)). RNA was analysed by microarray gene profiling using the Illumina HumanHT-12 v 4 Expression Beadchip. Following E + F treatments expression of genes encoding host defence molecules including DEFβ4A, DEFB103A, LCN2 as well as those associated with keratinisation eg CNFN and SPRR family genes were significantly enhanced (P < 0.05) compared to either E or F treatments alone. Mutation of estrogen responsive elements (EREs) identified in the DEFβ4 gene promoter abolished the augmented gene expression suggesting estrogen functioned directly through a regulatory mechanism involving ESR1/2. Ingenuity pathway analyses also suggested the pro-inflammatory cytokine IL-17A to regulate the vaginal host defences during infection. Pre-treating VK2 E6/E7 cells with estrogen (4 nM) and challenging with 1L-17A & F (12 h) significantly enhanced DEFβ4, DEF103A and S100A7 expression (P < 0.05). Origins of vaginal IL-17 in vivo remain unclear, but patient biopsies support γδ T cells located within the vaginal epithelium. These data suggest that the vaginal antimicrobial response induced by flagellin activation of Toll-like Receptor 5 cell signalling is augmented following topical estrogen application.

Do variations in labial anatomy have an effect on recurrent urinary tract infection?

INTRODUCTION AND HYPOTHESIS

Variations in labial anatomy may constitute a risk factor for vaginal pH increase and recurrent UTIs. Our objective in this study was to show the effects of variations in labial anatomy on vaginal pH and recurrent UTI.

METHODS

A total of 331 non-menopausal and sexually active patients between the ages of 18 and 50, meeting recurrent urinary infection criteria and not meeting exclusion criteria were included in the study in group 1, the infection group, and 440 patients without recurrent UTI were included in group 2, the control group. Vaginal pH values of the participants were measured. Labia minora were classified as labial anatomy based on the Banwell classification. Predisposing factors and demographic data were also questioned, measured, recorded, and compared.

RESULTS

A significant difference was detected in labial anatomy between groups 1 and 2 based on the Banwell classification. Banwell type 3 in group 1 (76%) and Banwell type 2 in group 2 (55%) were observed to be significantly higher. There was a significant difference in right and left vertical and horizontal dimensions of the labia minora between the two groups. It was also observed that the vaginal pH was significantly more alkaline in group 1 compared with group 2 (6.11 vs 4.48).

CONCLUSION

Although there are many causes of recurrent urinary tract infections, this study showed that vaginal pH imbalance and labia minora anatomy in the lower third prominence based on the Banwell classification (type 3) were among the most important causes. Thus, we think that the vaginal anatomy should be evaluated in recurrent UTI patients.

The mysteries of menopause and urogynecologic health: clinical and scientific gaps

OBJECTIVES

A significant body of knowledge implicates menopausal estrogen levels in the pathogenesis of the common pelvic floor disorders (PFDs). These health conditions substantially decrease quality of life, increase depression, social isolation, caregiver burden, and economic costs to the individuals and society.

METHODS

This review summarizes the epidemiology of the individual PFDs with particular attention to the understanding of the relationship between each PFD and menopausal estrogen levels, and the gaps in science and clinical care that affect menopausal women. In addition, we review the epidemiology of recurrent urinary tract infection (rUTI)-a condition experienced frequently and disproportionately by menopausal women and hypothesized to be potentiated by menopausal estrogen levels.

RESULTS

The abundance of estrogen receptors in the urogenital tract explains why the natural reduction of endogenous estrogen, the hallmark of menopause, can cause or potentiate PFDs and rUTIs. A substantial body of epidemiological literature suggests an association between menopause, and PFDs and rUTIs; however, the ability to separate this association from age and other comorbid conditions makes it difficult to draw definitive conclusions on the role of menopause alone in the development and/or progression of PFDs. Similarly, the causative link between the decline in endogenous estrogen levels and the pathogenesis of PFDs and rUTIs has not been well-established.

CONCLUSIONS

Innovative human studies, focused on the independent effects of menopausal estrogen levels, uncoupled from tissue and cellular senescence, are needed.

Behavioral and dietary risk factors of recurrent urinary tract infection in Chinese postmenopausal women: a case-control study

OBJECTIVE

The present study aimed to examine the behavioral and dietary risk factors of recurrent urinary tract infection (RUTI) in postmenopausal patients in China.

METHODS

We performed a population-based case-control study with 193 postmenopausal women with RUTI and 193 age-matched healthy female controls with no history of RUTI. The study was conducted between January 2016 and June 2018 in Changzhou, China. Data were collected using an interviewer-based questionnaire, including information on demographics, lifestyle behavior, and habitual diet. Conditional logistic regression analysis was conducted to examine the risk factors associated with RUTI.

RESULTS

Wiping from back to front after toilet use, sedentary behavior >6 hours/day, delayed voiding, and chronic constipation were associated with an increased risk of RUTI. Drinking more than three cups of green tea per month showed an inverse association with RUTI. However, there was no evidence of dose dependency for overall consumption. Additionally, the three-cup association involved a small proportion of cases and may reflect statistical artifact.

CONCLUSIONS

Wiping from back to front after toilet use, sedentary behavior, delayed voiding, and chronic constipation are associated with an increased risk of RUTI in postmenopausal women.

Reaching the End of the Line: Urinary Tract Infections

Urinary tract infections (UTIs) cause a substantial health care burden. UTIs (i) are most often caused by uropathogenic Escherichia coli (UPEC), (ii) primarily affect otherwise healthy females (50% of women will have a UTI), (iii) are associated with significant morbidity and economic impact, (iv) can become chronic, and (v) are highly recurrent. A history of UTI is a significant risk factor for a recurrent UTI (rUTI). In otherwise healthy women, an acute UTI leads to a 25 to 50% chance of rUTI within months of the initial infection. Interestingly, rUTIs are commonly caused by the same strain of E. coli that led to the initial infection, arguing that there exist host-associated reservoirs, like the gastrointestinal tract and underlying bladder tissue, that can seed rUTIs. Additionally, catheter-associated UTIs (CAUTI), caused by Enterococcus and Staphylococcus as well as UPEC, represent a major health care concern. The host's response of depositing fibrinogen at the site of infection has been found to be critical to establishing CAUTI. The Drug Resistance Index, an evaluation of antibiotic resistance, indicates that UTIs have become increasingly difficult to treat since the mid-2000s. Thus, UTIs are a "canary in the coal mine," warning of the possibility of a return to the preantibiotic era, where some common infections are untreatable with available antibiotics. Numerous alternative strategies for both the prevention and treatment of UTIs are being pursued, with a focus on the development of vaccines and small-molecule inhibitors targeting virulence factors, in the hopes of reducing the burden of urogenital tract infections in an antibiotic-sparing manner.

Vitamin D strengthens the bladder epithelial barrier by inducing tight junction proteins during E. coli urinary tract infection

Tight junction proteins are pivotal to prevent bacterial invasion of the epithelial barrier. We here report that supplementation with vitamin D can strengthen the urinary bladder lining. Vitamin D deficient and sufficient mice were infected with Escherichia coli (E. coli) transurethrally to cause urinary tract infection. In addition, bladder biopsies were obtained from postmenopausal women before and after a 3-month period of supplementation with 25-hydroxyvitamin D₃ (25D₃) and ex vivo infected with E. coli. In biopsies, obtained before E. coli infection, vitamin D had no impact on tight junction proteins. However, during E. coli infection, vitamin D induced occludin and claudin-14 in mature superficial umbrella cells of the urinary bladder, as demonstrated by immunohistochemistry. Increased cell-cell adhesion consolidating the epithelial integrity is thereby promoted. We here describe a novel role of vitamin D in the urinary tract supporting vitamin D supplementation to restore the bladder epithelial integrity.

Nonantibiotic prevention and management of recurrent urinary tract infection

Urinary tract infections (UTIs) are highly prevalent, lead to considerable patient morbidity, incur large financial costs to health-care systems and are one of the most common reasons for antibiotic use worldwide. The growing problem of antimicrobial resistance means that the search for nonantibiotic alternatives for the treatment and prevention of UTI is of critical importance. Potential nonantibiotic measures and treatments for UTIs include behavioural changes, dietary supplementation (such as Chinese herbal medicines and cranberry products), NSAIDs, probiotics, D-mannose, methenamine hippurate, estrogens, intravesical glycosaminoglycans, immunostimulants, vaccines and inoculation with less-pathogenic bacteria. Some of the results of trials of these approaches are promising; however, high-level evidence is required before firm recommendations for their use can be made. A combination of these agents might provide the optimal treatment to reduce recurrent UTI, and trials in specific population groups are required.

Prevention and treatment of uncomplicated lower urinary tract infections in the era of increasing antimicrobial resistance-non-antibiotic approaches: a systemic review

Purpose

Urinary tract infections (UTIs) are one of the more common infections encountered in everyday clinical practice. They account for 10–20% of all infections treated in primary care units and 30–40% of those treated in hospitals. The risk of UTI in the female population is considered to be 14 times higher than in the male population. The prevalence of bacterial etiology results in a large consumption of broad-spectrum antibiotics, which in turn leads to increased rates of resistant uropathogens. Therefore, non-antibiotic prevention and treatment options are now of great importance.

Methods

A systematic literature search was performed for the last 20 years (1999–2019) and the efficiencies of these eight different non-antibiotic interventions were analysed and discussed.

Results

This article provides an overview on non-antibiotic options for management of UTI, including the application of cranberry products, the phytodrug Canephron N, probiotics, nonsteroidal anti-inflammatory drugs (NSAID), d-mannose, estrogens, vitamins, and immunotherapy.

Conclusions

The last 20 years of research on non-antibiotic approaches in UTI have not brought conclusive evidence that antibiotic usage can be replaced completely by non-antibiotic options. Hence, antibiotics still remain a gold standard for UTI treatment and prevention. However, changing the therapeutic strategy by including non-antibiotic measures in the management of UTI could be successful in avoiding antimicrobial resistance at least to some extent.

Sex differences in IL-17 contribute to chronicity in male versus female urinary tract infection

Sex-based differences influence incidence and outcome of infectious disease. Women have a significantly greater incidence of urinary tract infection (UTI) than men, yet, conversely, male UTI is more persistent with greater associated morbidity. Mechanisms underlying these sex-based differences are unknown, in part due to a lack of experimental models. We optimized a model to transurethrally infect male mice and directly compared UTI in both sexes. Although both sexes were initially equally colonized by uropathogenic E. coli, only male and testosterone-treated female mice remained chronically infected for up to 4 weeks. Female mice had more robust innate responses, including higher IL-17 expression, and increased γδ T cells and group 3 innate lymphoid cells in the bladder following infection. Accordingly, neutralizing IL-17 abolished resolution in female mice, identifying a cytokine pathway necessary for bacterial clearance. Our findings support the concept that sex-based responses to UTI contribute to impaired innate immunity in males and provide a rationale for non-antibiotic-based immune targeting to improve the response to UTI.

Direct Detection of Tissue-Resident Bacteria and Chronic Inflammation in the Bladder Wall of Postmenopausal Women with Recurrent Urinary Tract Infection

Urinary tract infections (UTIs) are the most commonly reported infections in adult women and have high rates of recurrence, especially in postmenopausal women. Recurrent UTI (RUTI) greatly reduces quality of life, places a significant burden on the healthcare system, and contributes to antimicrobial resistance. Because treatment of RUTI by long-term antibiotic therapy is often ineffective or poorly tolerated in elderly women, new therapies must be developed. The molecular basis of RUTI, especially in postmenopausal women, has remained unclear because modeling RUTI in mice is difficult, and human data are limited. Invasion of the urothelium and induction of host inflammation are hypothesized to be key mechanisms by which bacterial pathogens cause RUTI. To further our understanding of RUTI in humans, we performed a systematic analysis of urine and bladder biopsy samples from postmenopausal women undergoing cystoscopy with fulguration of trigonitis in the advanced management of antibiotic-refractory RUTI. We provide direct evidence that bacteria reside in the bladder wall of postmenopausal RUTI patients and that diverse bacterial species can be isolated from the bladder tissue. Histopathological scoring revealed significant edema and alterations of urothelial architecture in RUTI patient biopsies. Lymphocytes, including plasma B-cells, were detected within the mesenchyme, urothelium, and follicular aggregates in the majority of patients, indicating that the local adaptive immune response is active during human RUTI. These data provide conclusive evidence that bacteria invade the human urothelium and suggest that diverse bacterial species and the adaptive immune response play important roles in RUTI in humans.

Urinary tract infection: Pathogenicity, antibiotic resistance and development of effective vaccines against Uropathogenic Escherichia coli

Urinary tract infections (UTIs) are recognized as one of the most common infectious diseases in the world that can be divided to different types. Uropathogenic Escherichia coli (UPEC) strains are the most prevalent causative agent of UTIs that applied different virulence factors such as fimbriae, capsule, iron scavenger receptors, flagella, toxins, and lipopolysaccharide for their pathogenicity in the urinary tract. Despite the high pathogenicity of UPEC strains, host utilizes different immune systems such as innate and adaptive immunity for eradication of them from the urinary tract. The routine therapy of UTIs is based on the use of antibiotics such as β-lactams, trimethoprim, nitrofurantoin and quinolones in many countries. Unfortunately, the widespread and misuse of these antibiotics resulted in the increasing rate of resistance to them in the societies. Increasing antibiotic resistance and their side effects on human body show the need to develop alternative strategies such as vaccine against UTIs. Developing a vaccine against UTI pathogens will have an important role in reduction the mortality rate as well as reducing economic costs. Different vaccines based on the whole cells (killed or live-attenuated vaccines) and antigens (subunits, toxins and conjugatedvaccines) have been evaluated against UTIs pathogens. Furthermore, other therapeutic strategies such as the use of probiotics and antimicrobial peptides are considered against UTIs. Despite the extensive efforts, limited success has been achieved and more studies are needed to reach an alternative of antibiotics for treatment of UTIs.

Lupinus mutabilis Edible Beans Protect against Bacterial Infection in Uroepithelial Cells

Lupinus mutabilis is a South American herb with edible beans, known to reduce serum glucose levels in diabetic patients. Furthermore, L. mutabilis contains phytochemicals known to decrease bacterial load. Based on the increased urinary tract infections experienced among patients with diabetes, we investigated the effect of L. mutabilis on bladder epithelial cells in the protection of E. coli infection during normal and high glucose concentrations. We did not observe any direct antibacterial effect by L. mutabilis extract. Instead we observed an influence on the host cells, with indirect impact on bacteria and their possibility of causing infection. L. mutabilis extract decreased adhesion to bladder epithelial cells of uropathogenic bacteria, including drug-resistant strains. Moreover, uroplakin1a, involved in adhesion, was downregulated while the antimicrobial peptide RNase 7 was upregulated in L. mutabilis treated cells irrespectively of glucose concentration. This supports an early effect fighting bacteria. Additionally, L. mutabilis prevented bacterial biofilm formation, which is used by bacteria to evade the immune system and antibiotics. In summary, L. mutabilis protects against bacterial infection in uroepithelial cells by preventing adhesion through alteration of the cell surface, increasing antimicrobial peptide expression, and reducing biofilm formation. Together, this promotes bacterial clearance, suggesting that L. mutabilis as extract or as a dietary item can contribute to the prevention of urinary tract infections, which is of importance in an era of increasing antibiotic resistance.

Why are diabetics prone to kidney infections?

People with diabetes mellitus are at higher risk of developing serious ascending infections of the urinary tract. The traditional explanation has focused on the role of glycosuria in promoting bacterial growth. Using mouse models, Murtha et al. demonstrate that when the intracellular insulin signaling pathway is compromised, antimicrobial defenses are compromised too, and the mice are unable to effectively handle uropathogenic E. coli introduced experimentally into the urinary tract. These observations strongly support the hypothesis that the antimicrobial defenses of the kidney are dependent on insulin, and the urinary tract infections associated with diabetes occur due to reduced expression of these key effectors of innate immunity.

Sex differences in lower urinary tract biology and physiology

Females and males differ significantly in gross anatomy and physiology of the lower urinary tract, and these differences are commonly discussed in the medical and scientific literature. However, less attention is dedicated to investigating the varied development, function, and biology between females and males on a cellular level. Recognizing that cell biology is not uniform, especially in the lower urinary tract of females and males, is crucial for providing context and relevance for diverse fields of biomedical investigation. This review serves to characterize the current understanding of biological sex differences between female and male lower urinary tracts, while identifying areas for future research. First, the differences in overall cell populations are discussed in the detrusor smooth muscle, urothelium, and trigone. Second, the urethra is discussed, including anatomic discussions of the female and male urethra followed by discussions of cellular differences in the urothelial and muscular layers. The pelvic floor is then reviewed, followed by an examination of the sex differences in hormonal regulation, the urinary tract microbiome, and the reticuloendothelial system. Understanding the complex and dynamic development, anatomy, and physiology of the lower urinary tract should be contextualized by the sex differences described in this review.

Immunomodulatory Effects of 17β-Estradiol on Epithelial Cells during Bacterial Infections

The innate immune system can function under hormonal control. 17β-Estradiol (E2) is an important sexual hormone for the reproductive cycle of mammals, and it has immunomodulatory effects on epithelial cells, which are the first line of defense against incoming bacteria. E2 regulates various pathophysiological processes, including the response to infection in epithelial cells, and its effects involve the regulation of innate immune signaling pathways, which are mediated through estrogen receptors (ERs). E2 modulates the expression of inflammatory and antimicrobial elements such as cytokines and antimicrobial peptides. The E2 effects on epithelial cells during bacterial infections are characterized by an increase in the production of antimicrobial peptides and by the diminution of the inflammatory response to abrogate proinflammatory cytokine induction by bacteria. Here, we review several novel molecular mechanisms through which E2 regulates the innate immune response of epithelial cells against bacterial infections.

Androgen exposure potentiates formation of intratubular communities and renal abscesses by Escherichia coli

Females across their lifespan and certain male populations are susceptible to urinary tract infections (UTI). The influence of female vs. male sex on UTI is incompletely understood, in part because preclinical modeling has been performed almost exclusively in female mice. Here, we employed established and new mouse models of UTI with uropathogenic Escherichia coli (UPEC) to investigate androgen influence on UTI pathogenesis. Susceptibility to UPEC UTI in both male and female hosts was potentiated with 5α-dihydrotestosterone, while males with androgen receptor deficiency and androgenized females treated with the androgen receptor antagonist enzalutamide were protected from severe pyelonephritis. In androgenized females and in males, UPEC formed dense intratubular, biofilm-like communities, some of which were sheltered from infiltrating leukocytes by the tubular epithelium and by peritubular fibrosis. Abscesses were nucleated by small intratubular collections of UPEC first visualized at five days postinfection and briskly expanded over the subsequent 24 hours. Male mice deficient in Toll-like receptor 4, which fail to contain UPEC within abscesses, were susceptible to lethal dissemination. Thus, androgen receptor activation imparts susceptibility to severe upper-tract UTI in both female and male murine hosts. Visualization of intratubular UPEC communities illuminates early renal abscess pathogenesis and the role of abscess formation in preventing dissemination of infection. Additionally, our study suggests that androgen modulation may represent a novel therapeutic route to combat recalcitrant or recurrent UTI in a range of patient populations.

Amaranthus caudatus extract inhibits the invasion of E. coli into uroepithelial cells

ETHNOPHARMACOLOGICAL RELEVANCE

Amaranthus caudatus is traditionally used to treat infections. Based on its traditional usage, we investigated the effect of A. caudatus on the bladder epithelial cells in the protection of E. coli infection.

MATERIALS AND METHODS

The direct antimicrobial effects of A. caudatus on uropathogenic bacteria were investigated using minimum inhibitory concentration (MIC) assay. Bladder epithelial cell lines T24 and 5637 and uropathogenic E. coli strain #12 were used to investigate the effect of A. caudatus. Bacterial adhesion and invasion into bladder cells treated with A. caudatus was analyzed. Expression of uroplakin-1a (UPK1A), β1 integrin (ITGB1), caveolin-1 (CAV1) and the antimicrobial peptides human β defensin-2 (DEFB4A) and LL-37 (CAMP) was evaluated using RT-PCR.

RESULTS

No direct antibacterial effect on E. coli or any of the tested uropathogenic strains was observed by A. caudatus. However, we demonstrated reduced mRNA expression of uroplakin-1a and caveolin-1, but not β1 integrin after treatment of uroepithelial cells, mirrored by the decreased adhesion and invasion of E. coli. A. caudatus treatment did not induce increased gene expression of the antimicrobial peptides, LL-37 and human β-defensin-2.

CONCLUSIONS

Our results showed that A. caudatus has a protective role on bladder epithelial cells against uropathogenic E. coli infection by decreasing the bacterial adhesion and invasion, thereby preventing infection.

High molecular weight hyaluronic acid: a two-pronged protectant against infection of the urogenital tract?

OBJECTIVES

Recurrent urinary tract infections are associated with uropathogenic Escherichia coli (UPEC) ascending and infecting the urinary tract. Antibiotics provide only symptomatic relief, not prevent recurrence. Clinical evidence suggests that intravesical glycosaminoglycan therapy, such as hyaluronic acid (HA), helps reduce UTI recurrence. This has been investigated here using in vitro systems modelling the urogenital tract tissues.

METHODS

RT4 bladder cells were preconditioned with high molecular weight HA (> 1500 kDa) at 2 mg mL-1 and challenged with UPEC to analyse barrier protection and bacterial adherence. Untreated and HA-preconditioned VK2 E6/E7 vaginal cells were challenged with E. coli flagellin (50 ng mL-1) to mimic bacterial challenge, and media analysed for lipocalin-2, human β-defensin 2 and interleukin-8 by ELISA. Experiments were repeated after siRNA knockdown of Toll-like receptors 2, 4 and 5, and CD44 to investigate signalling.

RESULTS

Microscopic analyses showed reduced bacterial adherence and urothelial disruption with HA, suggesting that HA functions as a barrier protecting the epithelium from bacterial infection. Cells treated with HA and flagellin simultaneously produced more of the host antimicrobial peptide LCN2 and pro-inflammatory IL-8 (P < 0.05) compared to the no HA/flagellin challenges. Increased gene expression of DEFB4 (P < 0.05), but not the hBD2 peptide, was observed in the HA/flagellin-challenged cells.

CONCLUSION

These data suggest that exogenous HA has potential to protect the urogenital epithelia from UPEC infection via a two-pronged approach that involves the physical enhancement of the epithelial barrier and augmentation of its innate immune response.