Urinary fungi associated with urinary symptom severity among women with interstitial cystitis/bladder pain syndrome (IC/BPS)

The microbiota in patients with interstitial cystitis/bladder pain syndrome: a systematic review

OBJECTIVE

To comprehensively review and critically assess the literature on microbiota differences between patients with interstitial cystitis (IC)/bladder pain syndrome (BPS) and normal controls and to provide clinical practice guidelines.

MATERIALS AND METHODS

In this systematic review, we evaluated previous research on microbiota disparities between IC/BPS and normal controls, as well as distinctions among IC/BPS subgroups. A comprehensive literature search was conducted across PubMed/MEDLINE, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials. Relevant studies were shortlisted based on predetermined inclusion and exclusion criteria, followed by quality assessment. The primary focus was identifying specific taxonomic variations among these cohorts.

RESULTS

A total of 12 studies met the selection criteria. Discrepancies were adjudicated by a third reviewer. The Newcastle-Ottawa Scale was used to assess study quality. Predominantly, the studies focused on disparities in urine microbiota between IC/BPS patients and normal controls, with one study examining gut microbiota differences between the groups, and two studies exploring vaginal microbiota distinctions. Unfortunately, analyses of discrepancies in other microbiota were limited. Our findings revealed evidence of distinct bacterial abundance variations, particularly involving Lactobacillus, alongside variations in specific metabolites among IC/BPS patients compared to controls.

CONCLUSIONS

Currently, there is evidence suggesting significant variations in the diversity and species composition of the urinary microbiota between individuals diagnosed with IC/BPS and control groups. In the foreseeable future, urologists should consider urine microbiota dysbiosis as a potential aetiology for IC, with potential clinical implications for diagnosis and treatment.

Ascomycetes yeasts: The hidden part of human microbiome

The fungal component of the microbiota, the mycobiota, has been neglected for a long time due to its poor richness compared to bacteria. Limitations in fungal detection and taxonomic identification arise from using metagenomic approaches, often borrowed from bacteriome analyses. However, the relatively recent discoveries of the ability of fungi to modulate the host immune response and their involvement in human diseases have made mycobiota a fundamental component of the microbial communities inhabiting the human host, deserving some consideration in host-microbe interaction studies and in metagenomics. Here, we reviewed recent data on the identification of yeasts of the Ascomycota phylum across human body districts, focusing on the most representative genera, that is, Saccharomyces and Candida. Then, we explored the key factors involved in shaping the human mycobiota across the lifespan, ranging from host genetics to environment, diet, and lifestyle habits. Finally, we discussed the strengths and weaknesses of culture-dependent and independent methods for mycobiota characterization. Overall, there is still room for some improvements, especially regarding fungal-specific methodological approaches and bioinformatics challenges, which are still critical steps in mycobiota analysis, and to advance our knowledge on the role of the gut mycobiota in human health and disease. This article is categorized under: Immune System Diseases > Genetics/Genomics/Epigenetics Immune System Diseases > Environmental Factors Infectious Diseases > Environmental Factors.

Urologic Chronic Pelvic Pain Syndrome Flares: A Comprehensive, Systematic Review and Meta-Analysis of the Peer-Reviewed Flare Literature

PURPOSE

We sought to systematically review and summarize the peer-reviewed literature on urologic chronic pelvic pain syndrome flares, including their terminology, manifestation, perceived triggers, management and prevention strategies, impact on quality of life, and insights into pathophysiologic mechanisms, as a foundation for future empirical research.

MATERIALS AND METHODS

We searched 6 medical databases for articles related to any aspect of symptom exacerbations for interstitial cystitis/bladder pain syndrome and chronic prostatitis/chronic pelvic pain syndrome. A total of 1486 abstracts and 398 full-text articles were reviewed, and data were extracted by at least 2 individuals.

RESULTS

Overall, we identified 59 articles, including 36 qualitative, cross-sectional, or case-control; 15 cohort-based; and 8 experimental articles. The majority of studies described North American patients with confirmed diagnoses. "Flare" was a commonly used term, but additional terminology (eg, exacerbation) was also used. Most flares involved significant increases in pain intensity, but less data were available on flare frequency and duration. Painful, frequent, long-lasting, and unpredictable flares were highly impactful, even over and above participants' nonflare symptoms. A large number of perceived triggers (eg, diet, stress) and management/prevention strategies (eg, analgesics, thermal therapy, rest) were proposed by participants, but few had empirical support. In addition, few studies explored underlying biologic mechanisms.

CONCLUSIONS

Overall, we found that flares are painful and impactful, but otherwise poorly understood in terms of manifestation (frequency and duration), triggers, treatment, prevention, and pathophysiology. These summary findings provide a foundation for future flare-related research and highlight gaps that warrant additional empirical studies.

Neonatal Cystitis Makes Adult Female Rat Urinary Bladders More Sensitive to Low Concentration Microbial Antigens

Purpose

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic pain disorder. Patients with IC/BPS often experience "flares" of symptom exacerbation throughout their lifetime, initiated by triggers, such as urinary tract infections. This study sought to determine whether neonatal bladder inflammation (NBI) alters the sensitivity of adult rat bladders to microbial antigens.

Methods

Female NBI rats received intravesical zymosan treatments on postnatal days P14-P16 while anesthetized; Neonatal Control Treatment (NCT) rats were anesthetized. In adults, bladder and spinal cord Toll-like receptor type 2 and 4 (TLR2, TLR4) contents were determined using ELISAs. Other rats were injected intravesically with lipopolysaccharide (LPS; mimics an E. coli infection; 25, 50, 100, or 200 μg/mL) or Zymosan (mimics yeast infection; 0.01, 0.1, 1, and 10 mg/mL) solutions on the following day. Visceromotor responses (VMRs; abdominal contractions) to graded urinary bladder distention (UBD, 10-60 mm Hg, 20s) were quantified as abdominal electromyograms (EMGs).

Results

Bladder TLR2 and TLR4 protein levels increased in NBI rats. These rats displayed statistically significant, dose-dependent, robustly augmented VMRs following all but the lowest doses of LPS and Zymosan tested, when compared with their adult treatment control groups. The NCT groups showed minimal responses to LPS in adults and minimally increased EMG measurements following the highest dose of Zymosan.

Conclusion

The microbial antigens LPS and Zymosan augmented nociceptive VMRs to UBD in rats that experienced NBI but had little effect on NCT rats at the doses tested. The greater content of bladder TLR2 and TLR4 proteins in the NBI group was consistent with increased responsiveness to their agonists, Zymosan and LPS, respectively. Given that patients with IC/BPS have a higher incidence of childhood urinary tract infections, this increased responsiveness to microbial antigens may explain the flares in symptoms following "subclinical" tract infections.

Urinary Tract Infection and Microbiome

Urinary tract infection is one of the most common bacterial infections and can cause major burdens, not only to individuals but also to an entire society. Current knowledge of the microbial communities in the urinary tract has increased exponentially due to next-generation sequencing and expanded quantitative urine culture. We now acknowledge a dynamic urinary tract microbiome that we once thought was sterile. Taxonomic studies have identified the normal core microbiota of the urinary tract, and studies on the changes in microbiome due to sexuality and age have set the foundation for microbiome studies in pathologic states. Urinary tract infection is not only caused by invading uropathogenic bacteria but also by changes to the uromicrobiome milieu, and interactions with other microbial communities can also contribute. Recent studies have provided insights into the pathogenesis of recurrent urinary tract infections and antimicrobial resistance. New therapeutic options for urinary tract infections also show promise; however, further research is needed to fully understand the implications of the urinary microbiome in urinary tract infections.

Uromycobiome in infants and toddlers with and without urinary tract infections

BACKGROUND

The bacterial components of the urobiome have been described in children, both with and without urinary tract infections (UTI). However, less is known about the pediatric uromycobiome: the community of fungi in the urine. The objectives of this study were to describe the uromycobiome in children and determine whether the uromycobiome differs between children with and without UTI.

METHODS

This was a cross-sectional study of febrile children less than 3 years of age who presented to the Emergency Department and had a catheterized urine sample sent as part of clinical care. We obtained residual urine for use in this study and identified components of the uromyobiome through amplification and sequencing of the fungal ITS2 region. We then compared the uromycobiome between those with and without UTI.

RESULTS

We included 374 children in this study (UTI = 50, no UTI = 324). Fungi were isolated from urine samples of 310 (83%) children. Fungi were identified in a higher proportion of children with UTI, compared to those without UTI (96% vs. 81%, p = 0.01). Shannon diversity index was higher in children with UTI, compared to those without (p = 0.04). Although there were differences in the most abundant taxa between children with and without UTI, there was no significant difference in beta diversity between groups.

CONCLUSIONS

Fungi were detected in the majority of catheterized urine samples from children. While a higher proportion of children with UTI had fungi in their urine, compared to children without UTI, there was no difference in the composition of these groups. A higher resolution version of the Graphical abstract is available as Supplementary information.

Possibilities and limitations of using low biomass samples for urologic disease and microbiome research

With the dogma of sterile urine no longer held as truth, numerous studies have implicated distinct changes in microbial diversity and composition to diseased subgroups in both benign and malignant urological diseases, ranging from overactive bladder to bladder and prostate cancer. Further facilitated by novel and effective techniques of urine culture and sequencing, analysis of the genitourinary microbiome holds high potential to identify biomarkers for disease and prognosis. However, the low biomass of samples included in microbiome studies of the urinary tract challenge researchers to draw definitive conclusions, confounded by technical and procedural considerations that must be addressed. Lack of samples and adequate true negative controls can lead to overestimation of microbial influence with clinical relevance. As such, results from currently available studies and assessment of their limitations required a thorough understanding. The purpose of this narrative review was to summarize notable microbiome studies in the field of urology with a focus on significant findings and limitations of study design. Methodological considerations in future research are also discussed.

A Perspective of the Urinary Microbiome in Lower Urinary Tract Infections - A Review

PURPOSE OF REVIEW

Greater availability of sequencing methods has broadened the knowledge of the urinary microbiome in an environment previously believed to be sterile. This review discusses internal and external influences that promote either a balance or a dysbiosis of the urinary tract and the future perspectives in understanding lower urinary tract infections.

RECENT FINDINGS

Efforts have been made to identify a "core" urinary microbiome in which Firmicutes and Bacteroidetes account for most of the bacterial representations. A shift to a Proteobacteria-dominant representation shapes the fingerprint of the infectious urinary microbiome; furthermore, the virome and the mycobiome are important modulators of the urinary microbiome, which have been recently explored to determine their role in the health-disease process of the lower urinary tract. A disturbance of bacterial representation and diversity triggers a transition from health to disease; conversely, a functional cooperative interplay between the host and microbiome allows for basic metabolic and immune functions to take place.

The healthy urinary microbiome in asymptomatic participants in the MAPP Network Study: Relation to gender, age, and menopausal status

INTRODUCTION

To understand the role of the urinary microbiome in disease states and interpret non-culture-based diagnostic urine testing of midstream urine specimens, we must have a better understanding of the urinary microbiome in asymptomatic, healthy individuals. We examined the impact of gender, age, and menopausal status on the healthy human urinary microbiome in asymptomatic control subjects enrolled in the multi-institution National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Multidisciplinary Approach to the Study of Chronic Pelvic Pain Network (MAPP) study.

METHODS

Asymptomatic, healthy controls, recruited to be ageand sex-matched to patients in the Trans-MAPP Epidemiology and Phenotyping Study, provided midstream urine collection for polymerase chain reaction (PCR)-electrospray ionization mass spectrometry identification of urinary microbiota. The microbiomes of male and female participants were described and analyzed for differences in composition and diversity at the species and genus level by sex, age, and, in females, by menopausal status.

RESULTS

Sixty-six total species were detected with a mean of 1.2 species (standard deviation [SD] 1.1) per male (n=97; mean age=43) and 2.3 (SD 1.3) per female (n=110, mean age=38) in asymptomatic, healthy controls. Species and genera diversity analyses showed significantly greater richness and diversity in females. With regard to species, Bifidobacterium subtile, Lactobacillus crispatus, and Lactobacillus johnsonii were more predominant in females. The genera Bifidobacterium, Staphylococcus, Lactobacillus, and Corynebacterium were more predominant in females, while for males the most prevalent organisms included Staphylococcus and Propionibacterium; only Propionibacterium approached a significant difference between genders. No significant difference in the presence and/or diversity of micro-organisms with menopausal status could be observed. Sex-specific age trends, particularly diversity, were larger for females than males.

CONCLUSIONS

These results suggest the urinary microbiome of healthy, asymptomatic subjects differed between genders and age in females, but not menopausal status. Gender differences may be attributable to the detection of urethral/vaginal organisms in females and prostate organisms in males. These findings will better allow us to interpret the results of microbiome reports in the midstream urine specimens of patients with urinary symptoms.

The bacterial microbiota of Hunner lesion interstitial cystitis/bladder pain syndrome

OBJECTIVE

To undertake the first comprehensive evaluation of the urinary microbiota associated with Hunner lesion (HL) interstitial cystitis/bladder pain syndrome (IC/BPS). Despite no previous identification of a distinct IC/BPS microbial urotype, HL IC/BPS, an inflammatory subtype of IC/BPS, was hypothesized most likely to be associated with a specific bacterial species or microbial pattern.

PARTICIPANTS AND METHODS

The bacterial microbiota of midstream urine specimens from HL IC/BPS and age- and gender-matched IC/BPS patients without HL (non-HL IC/BPS) were examined using the pan-bacterial domain clinical-level molecular diagnostic Pacific Biosciences full-length 16S gene sequencing protocol, informatics pipeline and database. We characterized the differential presence, abundances, and diversity of species, as well as gender-specific differences between and among HL and non-HL IC/BPS patients.

RESULTS

A total of 59 patients with IC/BPS were enrolled (29 HL, 30 non-HL; 43 women, 16 men) from a single centre and the microbiota in midstream urine specimens was available for comparison. The species abundance differentiation between the HL and non-HL groups (12 species) was not significantly different after Bonferroni adjustments for multiple comparisons. Similarly, the nine differentiating species noted between female HL and non-HL patients were not significantly different after similar statistical correction. However, four species abundances (out of the 10 species differences identified prior to correction) remained significantly different between male HL and non-HL subjects: Negativicoccus succinivorans, Porphyromonas somerae, Mobiluncus curtisii and Corynebacterium renale. Shannon diversity metrics showed significantly higher diversity among HL male patients than HL female patients (P = 0.045), but no significant diversity differences between HL and non-HL patients overall.

CONCLUSIONS

We were not able to identify a unique pathogenic urinary microbiota that differentiates all HL from all non-HL IC/BPS. It is likely that the male-specific differences resulted from colonization/contamination remote from the bladder. We were not able to show that bacteria play an important role in patients with HL IC/BPS.

Processing human urine and ureteral stents for 16S rRNA amplicon sequencing

Ureteral stents are commonly used medical devices that harbor a unique and patient-specific microbial community. This protocol describes an optimized procedure for high-quality DNA extraction from both urine and ureteral stent samples for the purpose of downstream microbiota characterization by amplicon sequencing. Detailed instruction is provided for 16S rRNA gene V4 region sequencing with the Illumina platform, which enables accurate and reproducible microbiota profiling of low bacterial abundance urine and stent samples.

For complete details on the use and execution of this protocol, please refer to Al et al. (2020).

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The urinary tract harbors low-abundance microbiota capable of influencing health

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Traditional sample preparation yields variable results vulnerable to contamination

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Protocol optimizes urological specimen processing for 16S rRNA amplicon sequencing

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The method ensures high-quality, reproducible urological microbiota data generation

Phenotypes of BPS/IC

Purpose of Review

The aim of this review is to summarise the latest research related to different phenotypes of BPS/IC, addressing the evidence for current well-defined phenotypes as well as identifying novel potential phenotypes and highlighting areas for future study.

Recent Findings

Two distinct phenotypes of BPS/IC are well-recognised: Hunner’s lesion disease and non-Hunner’s lesion BPS/IC. Recent studies have shown these phenotypes exhibit distinct clinical, pathological and cystoscopic features, and targeted treatment to Hunner’s lesions can prove effective. Recent studies have also identified new potential phenotypes based on biochemical, molecular and histological markers, pathophysiological mechanisms of disease, clinical features, cystoscopic findings, radiological features and urodynamic factors. This evidence has improved our understanding of the underlying mechanism of disease and may enable more personalised and targeted therapy in the future.

Summary

Novel phenotypes of BPS/IC relate to the presence of certain biomarkers, alterations in the urinary microbiome, the characteristics of pain and presence of co-existing somatic and psychosocial conditions, altered patterns of brain white matter changes and urodynamic features. Further study is required to evaluate whether these potential phenotypes are clinically useful based on their ability to guide treatment selection and predict outcome from therapy, and therefore optimise therapeutic outcomes.

Urinary microbiome in uncomplicated and interstitial cystitis: is there any similarity?

PURPOSE

Acute/uncomplicated cystitis is the most common bacterial infection causing inflammation in the bladder tissues and predominantly diagnosed in women. Interstitial cystitis may too, cause inflammation in the bladder but its etiology has been elusive. Even though the site and symptoms of both diseases are largely shared, state of the urinary microbiome in these disorders have not been comparatively evaluated before. The purpose of this review is to assess and qualitatively compare structure and composition of the urinary microbiome in acute/uncomplicated cystitis and interstitial cystitis.

METHODS AND RESULTS

The available literature in MEDLINE are extensively searched using keywords and screened. Pertinent evidence is carefully assessed and synthesized. We included the original studies with a cohort of medically stable, non-pregnant women with otherwise functionally normal urinary tract and excluded the original articles if the infection in a patient's cohort is accompanied by urinary syndromes such as incontinence and overactive bladder syndrome. A total of six original papers reporting on the urinary microbiome in acute cystitis and nine papers on the interstitial cystitis met the selection criteria.

CONCLUSION

The evidence we have gleaned from the literature on the urinary microbiome associated with the acute and interstitial cystitis does not point to convergence of microbiome similarities between the two diseases. More studies with direct sampling of the bladder tissues besides sampling bladder surfaces are warranted for accurate comparison of microbiome similarity between the two conditions. The future research on interstitial cystitis microbiome should include stratified cohorts with prospective design.

The Bladder is Not Sterile: an Update on the Urinary Microbiome

Purpose of Review

The article discusses (1) techniques used to study bacterial urinary microbiota; (2) existence of non-bacterial urinary microbiota; (3) associations between changes in urinary microbiota and various benign lower urinary tract disorders.

Recent Findings

Urine harbors a diverse microbial community that resides within it. A multitude of studies have identified differences in these communities associated with urologic conditions, suggesting that microbial communities may maintain normal bladder homeostasis. Technological advances in analytic approaches have improved our understanding of the urinary microbiome. The choice of urine sampling method (voided, catheterized, or aspirated) will significantly influence microbiome findings. Sex and age highly influence urinary microbiota; in addition to rigorous inclusion criteria, microbial studies must be sufficiently powered to overcome the substantial interindividual variability of urinary microbiota. Regardless of these complicating factors, studies have identified microbial patterns correlating with both urologic diagnoses and treatment responses.

Summary

Without a clear understanding of the variability of and exogenous influences on the urinary microbiota in the absence of disease, it has been challenging to reveal the microbial patterns responsible for disease pathophysiology. Host mechanisms in response to the urinary microbiome are also poorly understood. Additional research can address whether the manipulation of urinary microbiota will benefit lower urinary tract health.