Detection of intracellular bacterial communities in human urinary tract infection

Innovative Strategies to Overcome Antimicrobial Resistance and Tolerance

Antimicrobial resistance and tolerance are natural phenomena that arose due to evolutionary adaptation of microorganisms against various xenobiotic agents. These adaptation mechanisms make the current treatment options challenging as it is increasingly difficult to treat a broad range of infections, associated biofilm formation, intracellular and host adapted microbes, as well as persister cells and microbes in protected niches. Therefore, novel strategies are needed to identify the most promising drug targets to overcome the existing hurdles in the treatment of infectious diseases. Furthermore, discovery of novel drug candidates is also much needed, as few novel antimicrobial drugs have been introduced in the last two decades. In this review, we focus on the strategies that may help in the development of innovative small molecules which can interfere with microbial resistance mechanisms. We also highlight the recent advances in optimization of growth media which mimic host conditions and genome scale molecular analyses of microbial response against antimicrobial agents. Furthermore, we discuss the identification of antibiofilm molecules and their mechanisms of action in the light of the distinct physiology and metabolism of biofilm cells. This review thus provides the most recent advances in host mimicking growth media for effective drug discovery and development of antimicrobial and antibiofilm agents.

The Clinical Trial Outcomes of Cranberry, D-Mannose and NSAIDs in the Prevention or Management of Uncomplicated Urinary Tract Infections in Women: A Systematic Review

The use of antibiotics in the treatment of UTIs is contributing to resistance. Hence, the outcome of human clinical trials of nonantibiotic remedies for preventing or treating UTI is of significant interest. This systematic review aimed to identify, summarise and evaluate the evidence for the outcomes of different nonantibiotic options including cranberry, D-mannose and non-steroidal anti-inflammatory drugs (NSAIDs). PubMed, Embase and Scopus were searched for manuscripts relating to nonantibiotic treatment of UTI including cranberry, mannose and NSAIDs. After title and abstract screening, data were extracted from 21 papers that were published in English and related to the treatment or prevention of uncomplicated UTI in adult women. We identified twelve papers examining the effects of cranberry, two papers examining D-mannose, two papers examining combination treatments (cranberry and D-mannose) and five manuscripts investigating the effects of NSAIDs. There is low-level evidence, from a small number of studies, supporting the use of D-mannose or combination treatments for potentially preventing UTIs in adult women without producing burdening side effects. However, larger and more randomised double-blinded trials are needed to confirm this. In comparison, the multiple studies of cranberry and NSAIDs produced conflicting evidence regarding their effectiveness.

Intracellular bacterial communities in patient with recurrent urinary tract infection caused by Staphylococcus spp and Streptococcus agalactiae: a case report and literature review

Background

 Urinary tract infections (UTI) are among the most frequent pathologies worldwide. Uropathogenic Escherichia coli (UPEC) is the leading etiological agent; however, depending on the patient's characteristics, the etiology may include some atypical pathogens. Some pathogenic bacteria can internalize in the urothelial and phagocytic cells complicating treatment and timely diagnosis.

Case presentation

We present a clinical case of a married female patient with urological alteration, constant catheterization, and urethral dilation with recurrent UTI for ten years, with five episodes per year and reports of negative urine culture. The microscopic analysis revealed intracellular bacterial communities (IBC) and pyocytes with active bacteria. A protocol was designed for the release of intracellular bacteria in urine samples; without the proposed treatment, the urine culture was negative. However, upon releasing the internalized bacteria, we obtained a polymicrobial urine culture. We isolated and identified Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus simulans, and Streptococcus agalactiae. All microorganisms were sensitive to nitrofurans and sulfas. The patient is under treatment with nitrofurantoin and continuous follow-up by our workgroup.

Conclusions

 It is essential to look for IBC and pyocytes with active bacteria in patients with recurrent UTIs to avoid false-negative urine culture results and provide timely treatment. Polymicrobial culture must be considered depending on the patient and clinical history.

Qualitative Analysis of a Twitter-Disseminated Survey Reveals New Patient Perspectives on the Impact of Urinary Tract Infection

Few studies have harnessed social media to explore patients' experiences with urinary tract infection (UTI); therefore, we captured UTI experiences and future research suggestions through a Twitter-disseminated survey. The survey posed three qualitative questions inquiring about the impact of UTIs, greatest UTI management hurdle, and research suggestions. We also asked participants to rate how seriously others perceive UTIs and the importance of UTIs in their life (scale: 1-100 (highest)). The study period spanned from January to June 2021. Coding was performed in duplicate, followed by thematic analysis. Of 466 participants from 22 countries, 128 considered their UTIs recurrent (n = 43) or chronic (n = 85). Six major themes emerged: UTIs drastically impact (1) physical and (2) mental health and (3) cause severe limitations in life activities. Patients reported (4) negative clinician interactions and perceived inadequate care, (5) a lack of knowledge and awareness surrounding UTIs, and (6) research gaps in UTI diagnostics and treatment. The participants considered UTIs extremely important (median: 100, IQR: 90-100), but characterized others' perceptions of them as less serious (median: 20, IQR: 10-30). Our survey revealed a patient population struggling with UTIs, particularly chronic UTIs. Our findings highlight perceived shortcomings in current UTI treatment and diagnostics.

Metabolic and Morphotypic Trade-Offs within the Eco-Evolutionary Dynamics of Escherichia coli

Escherichia coli arbitrarily encompasses facultative anaerobic, rod-shaped bacteria with defined respiratory and fermentative types of metabolism. The species diversification has been further advanced by atypical strains whose features deviate from the essential species-specific morphological and metabolic cutoff. The morphological cutoff is exemplified by bacterial filamentation. E. coli filamentation has been studied from two different perspectives: the first considers filamentation as a result of adaptive strategies and response to stress, while the second is based on findings from the cell division of E. coli's conditional mutants. Another cutoff is represented by E. coli's inability to use citrate as a sole carbon and energy source. In this study, we compared two atypical E. coli strains that belong to the same neuroinvasive ecovar but exhibit either of the two phenotypes that deviate from the species' features. While E. coli RS218 exists in the form of filaments incapable of growth on citrate, strain IHE3034 is represented as normal-sized bacteria able to ferment citrate under oxic conditions in the presence of glucose; in this paper, we show that these two phenotypes result from a bona fide trade-off. With the help of comparative proteomics and metabolomics, we discovered the proteome required for the upkeep of these phenotypes. The metabolic profiles of both strains reveal that under aerobic conditions, RS218 undergoes oxidative metabolism, while IHE3034 undergoes anaerobic respiration. Finally, we show that the use of citrate and filament formation are both linked in a trade-off occurring via a c-di-GMP-dependent phase variation event. IMPORTANCE Aerobic use of citrate and filamentous growth are arbitrary cutoffs for the Escherichia coli species. The strains that exhibit them as stable phenotypes are called atypical. In this study, we compare two atypical neuroinvasive E. coli strains, which alternatively display either of these phenotypes. We present the proteome and metabolome required for the maintenance of filamentous growth and show that anaerobic nitrate respiration is the main requirement for the use of citrate. The fact that the two phenotypes are differentially expressed by each strain prompted us to check if they are part of a trade-off. Indeed, these atypical characters are reversible and result from a c-di-GMP phase variation event. Thus, we revealed hidden links between stable morphological and metabolic phenotypes and provided information about alternative evolutionary pathways for the survival of E. coli strains in various host niches.

Morphological instability and roughening of growing 3D bacterial colonies

The morphogenesis of two-dimensional bacterial colonies has been well studied. However, little is known about the colony morphologies of bacteria growing in three dimensions, despite the prevalence of three-dimensional environments (e.g., soil, inside hosts) as natural bacterial habitats. Using experiments on bacteria in granular hydrogel matrices, we find that dense multicellular colonies growing in three dimensions undergo a common morphological instability and roughen, adopting a characteristic broccoli-like morphology when they exceed a critical size. Analysis of a continuum “active fluid” model of the expanding colony reveals that this behavior originates from an interplay of competition for nutrients with growth-driven colony expansion, both of which vary spatially. These results shed light on the fundamental biophysical principles underlying growth in three dimensions.

How do growing bacterial colonies get their shapes? While colony morphogenesis is well studied in two dimensions, many bacteria grow as large colonies in three-dimensional (3D) environments, such as gels and tissues in the body or subsurface soils and sediments. Here, we describe the morphodynamics of large colonies of bacteria growing in three dimensions. Using experiments in transparent 3D granular hydrogel matrices, we show that dense colonies of four different species of bacteria generically become morphologically unstable and roughen as they consume nutrients and grow beyond a critical size—eventually adopting a characteristic branched, broccoli-like morphology independent of variations in the cell type and environmental conditions. This behavior reflects a key difference between two-dimensional (2D) and 3D colonies; while a 2D colony may access the nutrients needed for growth from the third dimension, a 3D colony inevitably becomes nutrient limited in its interior, driving a transition to unstable growth at its surface. We elucidate the onset of the instability using linear stability analysis and numerical simulations of a continuum model that treats the colony as an “active fluid” whose dynamics are driven by nutrient-dependent cellular growth. We find that when all dimensions of the colony substantially exceed the nutrient penetration length, nutrient-limited growth drives a 3D morphological instability that recapitulates essential features of the experimental observations. Our work thus provides a framework to predict and control the organization of growing colonies—as well as other forms of growing active matter, such as tumors and engineered living materials—in 3D environments.

What are the risk factors for recurrent UTI with repeated ESBL-producing Enterobacteriaceae? A retrospective cohort study

INTRODUCTION

A previous study has shown that two-thirds of patients with urinary tract infections (UTIs) caused by extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae experience recurrence with the same bacteria on subsequent UTI episodes. However, little is known about which patients suffer from UTI due to ESBL-producing Enterobacteriaceae repeatedly. This study aimed to investigate the risk factors for recurrent UTI due to repeated ESBL-producing organism infections.

METHODS

This retrospective, single-center, observational cohort study screened all patients with UTI caused by ESBL-producing strains between January 2012 and April 2019. Among the patients who were followed up, patients who experienced UTI recurrence were enrolled and divided into two groups: ESBL recurrence group and non-ESBL recurrence group. Multivariable Cox proportional hazards regression analyses were performed to evaluate the association between patient characteristics and the development of recurrent UTI caused by ESBL-producing Enterobacteriaceae.

RESULTS

A total of 330 patients were followed up after the diagnosis of UTI caused by ESBL-producing organisms. Among the patients, 115 (34.8%) experienced UTI recurrence, and 71 (61.7%) of them experienced subsequent recurrent UTI due to ESBL-producing organisms. Patient's age (hazard ratio [HR], 1.02; 95% confidence interval [CI], 1.00-1.04; P = 0.046) and recurrent UTI history (HR, 1.69; 95% CI, 1.05-2.72; P = 0.031) were significantly associated with an increased risk of recurrence with ESBL-producing Enterobacteriaceae.

CONCLUSION

These findings showed that a history of previous frequent UTI recurrence is the risk factor for recurrence of UTI due to repeated ESBL producing Enterobacteriaceae infections.

The potential role of ischaemia-reperfusion injury in chronic, relapsing diseases such as rheumatoid arthritis, Long COVID, and ME/CFS: evidence, mechanisms, and therapeutic implications

Ischaemia-reperfusion (I-R) injury, initiated via bursts of reactive oxygen species produced during the reoxygenation phase following hypoxia, is well known in a variety of acute circumstances. We argue here that I-R injury also underpins elements of the pathology of a variety of chronic, inflammatory diseases, including rheumatoid arthritis, ME/CFS and, our chief focus and most proximally, Long COVID. Ischaemia may be initiated via fibrin amyloid microclot blockage of capillaries, for instance as exercise is started; reperfusion is a necessary corollary when it finishes. We rehearse the mechanistic evidence for these occurrences here, in terms of their manifestation as oxidative stress, hyperinflammation, mast cell activation, the production of marker metabolites and related activities. Such microclot-based phenomena can explain both the breathlessness/fatigue and the post-exertional malaise that may be observed in these conditions, as well as many other observables. The recognition of these processes implies, mechanistically, that therapeutic benefit is potentially to be had from antioxidants, from anti-inflammatories, from iron chelators, and via suitable, safe fibrinolytics, and/or anti-clotting agents. We review the considerable existing evidence that is consistent with this, and with the biochemical mechanisms involved.

Filamentous morphology of bacterial pathogens: regulatory factors and control strategies

Several studies have demonstrated that when exposed to physical, chemical, and biological stresses in the environment, many bacteria (Gram-positive and Gram-negative) change their morphology from a normal cell to a filamentous shape. The formation of filamentous morphology is one of the survival strategies against environmental stress and protection against phagocytosis or protist predators. Numerous pathogenic bacteria have shown filamentous morphologies when examined in vivo or in vitro. During infection, certain pathogenic bacteria adopt a filamentous shape inside the cell to avoid phagocytosis by immune cells. Filamentous morphology has also been seen in biofilms formed on biotic or abiotic surfaces by certain bacteria. As a result, in addition to protecting against phagocytosis by immune cells or predators, the filamentous shape aids in biofilm adhesion or colonization to biotic or abiotic surfaces. Furthermore, these filamentous morphologies of bacterial pathogens lead to antimicrobial drug resistance. Clinically, filamentous morphology has become one of the most serious challenges in treating bacterial infection. The current review went into great detail about the various factors involved in the change of filamentous morphology and the underlying mechanisms. In addition, the review discussed a control strategy for suppressing filamentous morphology in order to combat bacterial infections. Understanding the mechanism underlying the filamentous morphology induced by various environmental conditions will aid in drug development and lessen the virulence of bacterial pathogens. KEY POINTS: • The bacterial filamentation morphology is one of the survival mechanisms against several environmental stress conditions and protection from phagocytosis by host cells and protist predators. • The filamentous morphologies in bacterial pathogens contribute to enhanced biofilm formation, which develops resistance properties against antimicrobial drugs. • Filamentous morphology has become one of the major hurdles in treating bacterial infection, hence controlling strategies employed for inhibiting the filamentation morphology from combating bacterial infections.

Virulence Mechanisms of Common Uropathogens and Their Intracellular Localisation within Urothelial Cells

A recurrent urinary tract infection (UTI) is a common debilitating condition whereby uropathogens are able to survive within the urinary tract. In this study, we aimed to determine if the common uropathogens Escherichia coli, Enterococcus faecalis, and Group B Streptococcus possessed virulence mechanisms that enable the invasion of urothelial cells. Urothelial cells were isolated from women with detrusor overactivity and recurrent UTIs; the intracellular localisation of the uropathogens was determined by confocal microscopy. Uropathogens were also isolated from women with acute UTIs and their intracellular localisation and virulence mechanisms were examined (yeast agglutination, biofilm formation, and haemolysis). Fluorescent staining and imaging of urothelial cells isolated from women with refractory detrusor overactivity and recurrent UTIs demonstrated that all three uropathogens were capable of intracellular colonisation. Similarly, the bacterial isolates from women with acute UTIs were also seen to intracellularly localise using an in vitro model. All Enterococcus and Streptococcus isolates possessed a haemolytic capacity and displayed a strong biofilm formation whilst yeast cell agglutination was unique to Escherichia coli. The expression of virulence mechanisms by these uropathogenic species was observed to correlate with successful urothelial cell invasion. Invasion into the bladder urothelium was seen to be a common characteristic of uropathogens, suggesting that bacterial reservoirs within the bladder contribute to the incidence of recurrent UTIs.

A Model of Intracellular Persistence of Pseudomonas aeruginosa in Airway Epithelial Cells

Pseudomonas aeruginosa (P.a.) is a major human pathogen capable of causing chronic infections in hosts with weakened barrier functions and host defenses, most notably airway infections commonly observed in individuals with the genetic disorder cystic fibrosis (CF). While mainly described as an extracellular pathogen, previous in vitro studies have described the molecular events leading to P.a. internalization in diverse epithelial cell types. However, the long-term fate of intracellular P.a. remains largely unknown. Here, we developed a model allowing for a better understanding of long-term (up to 120 h) intracellular bacterial survival in the airway epithelial cell line BEAS-2B. Using a tobramycin protection assay, we characterized the internalization, long-term intracellular survival, and cytotoxicity of the lab strain PAO1, as well as clinical CF isolates, and conducted analyses at the single-cell level using confocal microscopy and flow cytometry techniques. We observed that infection at low multiplicity of infection allows for intracellular survival up to 120 h post-infection without causing significant host cytotoxicity. Finally, infection with clinical isolates revealed significant strain-to-strain heterogeneity in intracellular survival, including a high persistence phenotype associated with bacterial replication within host cells. Future studies using this model will further elucidate the host and bacterial mechanisms that promote P. aeruginosa intracellular persistence in airway epithelial cells, a potentially unrecognized bacterial reservoir during chronic infections.

Urinary Tract Infection in Overactive Bladder: An Update on Pathophysiological Mechanisms

Overactive bladder (OAB) is a clinical syndrome defined by urinary urgency, increased daytime urinary frequency and/or nocturia, with or without urinary incontinence, that affects approximately 11% of the western population. OAB is accepted as an idiopathic disorder, and is charactersied clinically in the absence of other organic diseases, including urinary tract infection. Despite this, a growing body of research provides evidence that a significant proportion of OAB patients have active bladder infection. This review discusses the key findings of recent laboratory and clinical studies, providing insight into the relationship between urinary tract infection, bladder inflammation, and the pathophysiology of OAB. We summarise an array of clinical studies that find OAB patients are significantly more likely than control patients to have pathogenic bacteria in their urine and increased bladder inflammation. This review reveals the complex nature of OAB, and highlights key laboratory studies that have begun to unravel how urinary tract infection and bladder inflammation can induce urinary urgency and urinary frequency. The evidence presented in this review supports the concept that urinary tract infection may be an underappreciated contributor to the pathophysiology of some OAB patients.

Commensal Urinary Lactobacilli Inhibit Major Uropathogens In Vitro With Heterogeneity at Species and Strain Level

The human urinary microbiome is thought to affect the development and progression of urinary tract infections (UTI), particularly recurrent UTIs in aging populations of women. To understand the possible interactions of urinary pathogens with commensal bacteria inhabiting the aging bladder, we conducted an initial functional assessment of a representative set of urinary lactobacilli that dominate this niche in postmenopausal women. We created a repository of urinary bladder bacteria isolated via Enhanced Quantitative Urinary Culture (EQUC) from healthy postmenopausal women, as well as those with a culture-proven recurrent UTI (rUTI) diagnosis. This repository contains lactobacilli strains from eight different species. As many other lactobacilli are known to inhibit human pathogens, we hypothesized that some urinary lactobacilli will have similar abilities to inhibit the growth of typical uropathogens and thus, provide a link between the urinary microbiome and the predisposition to the rUTI. Therefore, we screened the urinary lactobacilli in our repository for their ability to inhibit model uropathogens in vitro. We observed that many urinary isolates strongly inhibit model strains of gram-negative Escherichia coli and Klebsiella pneumoniae but demonstrate less inhibition of gram-positive Enterococcus faecalis. The observed inhibition affected model strains of uropathogens as well as clinical and multidrug-resistant isolates of those species. Our preliminary analysis of inhibition modes suggests a combination of pH-dependent and cell-dependent inhibition. Overall, inhibition strongly varies among species and strains of urinary lactobacilli. While the strength of the inhibition is not predictive of health outcomes in this limited repository, there is a high level of species and strain diversity that warrants future detailed investigations.

Reduced urothelial expression of uroplakin-IIIa in cystitis areas in bladders of postmenopausal women with recurrent urinary tract infections: pilot study

PURPOSE

To study human bladder biopsies to investigate urothelial response to UTI, expression of uroplakin, and urothelial response after healing from cystoscopy with electrofulguration (CEF) treatment for antibiotic-recalcitrant RUTI.

METHODS

Following IRB approval, cold cup bladder biopsies from "no cystitis" and "cystitis" regions were obtained from women with antibiotic-recalcitrant rUTI undergoing CEF under anesthesia. "No cystitis" and "cystitis" biopsies from 14 patients (5 had prior CEF, 9 naïve) were analyzed by immunofluorescence (IF) confocal microscopy using antibodies against uroplakin-IIIa. For an additional 6 patients (2 prior CEF, 4 naïve), only "cystitis" area biopsies were taken and analyzed. Cytokeratin 5 (marker for squamous metaplasia) staining was performed on 14 patients.

RESULTS

In healthy tissue, uroplakin-IIIa staining was observed as a contiguous line on the luminal surface of umbrella cells. In "cystitis" areas for 19/20 patients, there was either no uroplakin-IIIa staining observed or spotty (+) staining. The "cystitis" regions of all patients had less intense uroplakin-IIIa staining compared to the matched "no cystitis" area in the same patient. In patients post-CEF but requiring repeat EF for persistent RUTI lesions, healed areas served as control and in 3 of 7 patients no uroplakin-IIIa staining was observed. Squamous metaplasia was observed in 10 patients.

CONCLUSION

In bladders of postmenopausal women with antibiotic-recalcitrant RUTI, areas with visible cystitis expressed less uroplakin-IIIa, supporting the model of urothelial exfoliation in response to UTI.

Rapid Detection of Bacterial Pathogens and Antimicrobial Resistance Genes in Clinical Urine Samples With Urinary Tract Infection by Metagenomic Nanopore Sequencing

Urinary tract infections (UTIs) are among the most common acquired bacterial infections in humans. The current gold standard method for identification of uropathogens in clinical laboratories is cultivation. However, culture-based assays have substantial drawbacks, including long turnaround time and limited culturability of many potential pathogens. Nanopore sequencing technology can overcome these limitations and detect pathogens while also providing reliable predictions of drug susceptibility in clinical samples. Here, we optimized a metagenomic nanopore sequencing (mNPS) test for pathogen detection and identification in urine samples of 76 patients with acute uncomplicated UTIs. We first used twenty of these samples to show that library preparation by the PCR Barcoding Kit (PBK) led to the highest agreement of positive results with gold standard clinical culture tests, and enabled antibiotic resistance detection in downstream analyses. We then compared the detection results of mNPS with those of culture-based diagnostics and found that mNPS sensitivity and specificity of detection were 86.7% [95% confidence interval (CI), 73.5-94.1%] and 96.8% (95% CI, 82.4-99.9%), respectively, indicating that the mNPS method is a valid approach for rapid and specific detection of UTI pathogens. The mNPS results also performed well at predicting antibiotic susceptibility phenotypes. These results demonstrate that our workflow can accurately diagnose UTI-causative pathogens and enable successful prediction of drug-resistant phenotypes within 6 h of sample receipt. Rapid mNPS testing is thus a promising clinical diagnostic tool for infectious diseases, based on clinical urine samples from UTI patients, and shows considerable potential for application in other clinical infections.

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.

Bladder epithelial cell phosphate transporter inhibition protects mice against uropathogenic Escherichia coli infection

Urinary tract infections are predominantly caused by uropathogenic Escherichia coli (UPEC). UPEC infects bladder epithelial cells (BECs) via fusiform vesicles, escapes into the cytosol to evade exocytosis, and establishes intracellular bacterial communities (IBCs) for the next round of infection. The UPEC vesicle escape mechanism remains unclear. Here we show that UPEC senses host immune responses and initiates escape by upregulating a key phospholipase. The UPEC phospholipase PldA disrupts the vesicle membrane, and pldA expression is activated by phosphate reduction in vesicles. The host phosphate transporter PIT1 is located on the fusiform vesicle membrane, transporting phosphate into the cytosol. UPEC infection upregulates PIT1 via nuclear factor κB (NF-κB), resulting in phosphate reduction. Silencing PIT1 blocks UPEC vesicle escape in BECs, inhibits IBC formation in mouse bladders, and protects mice from UPEC infection. Our results shed light on pathogenic bacteria responding to intracellular phosphate shortage and tackling host defense and provide insights for development of new therapeutic agents to treat UPEC infection.

Bacterial filamentation as a mechanism for cell-to-cell spread within an animal host

Intracellular pathogens are challenged with limited space and resources while replicating in a single host cell. Mechanisms for direct invasion of neighboring host cells have been discovered in cell culture, but we lack an understanding of how bacteria directly spread between host cells in vivo. Here, we describe the discovery of intracellular bacteria that use filamentation for spreading between the intestinal epithelial cells of a natural host, the rhabditid nematode Oscheius tipulae. The bacteria, which belong to the new species Bordetella atropi, can infect the nematodes following a fecal-oral route, and reduce host life span and fecundity. Filamentation requires UDP-glucose biosynthesis and sensing, a highly conserved pathway that is used by other bacteria to detect rich conditions and inhibit cell division. Our results indicate that B. atropi uses a pathway that normally regulates bacterial cell size to trigger filamentation inside host cells, thus facilitating cell-to-cell dissemination.

Some intracellular pathogens can directly invade neighboring host cells in cell culture, but it is unclear how this happens in vivo. Here, Tran et al. describe an intracellular bacterium that forms filaments to spread between intestinal epithelial cells in its host nematode, in a process regulated by a conserved nutrient-sensing pathway.

A Novel Propidium Monoazide-Based PCR Assay Can Measure Viable Uropathogenic E. coli In Vitro and In Vivo

Background

Polymerase chain reaction (PCR) is an important means by which to study the urine microbiome and is emerging as possible alternative to urine cultures to identify pathogens that cause urinary tract infection (UTI). However, PCR is limited by its inability to differentiate DNA originating from viable, metabolically active versus non-viable, inactive bacteria. This drawback has led to concerns that urobiome studies and PCR-based diagnosis of UTI are confounded by the presence of relic DNA from non-viable bacteria in urine. Propidium monoazide (PMA) dye can penetrate cells with compromised cell membranes and covalently bind to DNA, rendering it inaccessible to amplification by PCR. Although PMA has been shown to differentiate between non-viable and viable bacteria in various settings, its effectiveness in urine has not been previously studied. We sought to investigate the ability of PMA to differentiate between viable and non-viable bacteria in urine.

Methods

Varying amounts of viable or non-viable uropathogenic E. coli (UTI89) or buffer control were titrated with mouse urine. The samples were centrifuged to collect urine sediment or not centrifuged. Urine samples were incubated with PMA and DNA cross-linked using blue LED light. DNA was isolated and uidA gene-specific PCR was performed. For in vivo studies, mice were inoculated with UTI89, followed by ciprofloxacin treatment or no treatment. After the completion of ciprofloxacin treatment, an aliquot of urine was plated on non-selective LB agar and another aliquot was treated with PMA and subjected to uidA-specific PCR.

Results

PMA’s efficiency in excluding DNA signal from non-viable bacteria was significantly higher in bacterial samples in phosphate-buffered saline (PBS, dC_T=13.69) versus bacterial samples in unspun urine (dC_T=1.58). This discrepancy was diminished by spinning down urine-based bacterial samples to collect sediment and resuspending it in PBS prior to PMA treatment. In 3 of 5 replicate groups of UTI89-infected mice, no bacteria grew in culture; however, there was PCR amplification of E. coli after PMA treatment in 2 of those 3 groups.

Conclusion

We have successfully developed PMA-based PCR methods for amplifying DNA from live bacteria in urine. Our results suggest that non-PMA bound DNA from live bacteria can be present in urine, even after antibiotic treatment. This indicates that viable but non-culturable E. coli can be present following treatment of UTI, and may explain why some patients have persistent symptoms but negative urine cultures following UTI treatment.

Bladder Ultrastructure and Urinary Cytokine Abnormality in Patients with Recurrent Urinary Tract Infection and the Changes after Intravesical Platelet-Rich Plasma Injections

This study investigates the bladder from patients with recurrent urinary tract infection (rUTI) at baseline and after intravesical platelet-rich plasma (PRP) injections. Patients with rUTI who underwent repeated intravesical PRP injections provided bladder and urine specimens at baseline and after treatment. Bladder specimens were investigated with electron microscopy and Western blotting. The urine sample was analyzed with commercially available Milliplex immunoassays. A total of 29 patients were enrolled. At baseline, the rUTI bladders exhibited defects of integrity in umbrella cells, a widened tight junction, and lysed organelles. Intracellular bacterial community incubations in the epithelial cells were also noted. Improvement in bladder defects after PRP injection was noted in 25–42% of patients. Bladder UPK3 expression was significantly lower in the patients with rUTI than in controls. Baseline levels of urinary inflammatory cytokine interleukin (IL)-6, IL-8, and brain-derived neurotrophic factor were higher in the patients with rUTI than in the controls, but there were lower levels of vascular endothelial growth factor and nerve growth factor. In the patients with rUTI who recovered from acute infection, the bladders still had immature urothelium, various ultrastructural defects, and elevated urinary inflammatory cytokines. PRP injection has the potential to promote bladder recovery in some of these patients.

Transcriptional alterations in bladder epithelial cells in response to infection with different morphological states of uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) may undergo a cyclic cascade of morphological alterations that are believed to enhance the potential of UPEC to evade host responses and re-infect host cell. However, knowledge on the pathogenic potential and host activation properties of UPEC during the morphological switch is limited. Microarray analysis was performed on mRNA isolated from human bladder epithelial cells (HBEP) after exposure to three different morphological states of UPEC (normal coliform, filamentous form and reverted form). Cells stimulated with filamentous bacteria showed the lowest number of significant gene alterations, although the number of enriched gene ontology classes was high suggesting diverse effects on many different classes of host genes. The normal coliform was in general superior in stimulating transcriptional activity in HBEP cells compared to the filamentous and reverted form. Top-scored gene entities activated by all three morphological states included IL17C, TNFAIP6, TNF, IL20, CXCL2, CXCL3, IL6 and CXCL8. The number of significantly changed canonical pathways was lower in HBEP cells stimulated with the reverted form (32 pathways), than in cells stimulated with the coliform (83 pathways) or filamentous bacteria (138 pathways). A host cell invasion assay showed that filamentous bacteria were unable to invade bladder cells, and that the number of intracellular bacteria was markedly lower in cells infected with the reverted form compared to the coliform. In conclusion, the morphological state of UPEC has major impact on the host bladder response both when evaluating the number and the identity of altered host genes and pathways.

Bladder Exposure to Gardnerella Activates Host Pathways Necessary for Escherichia coli Recurrent UTI

Recurrent urinary tract infections (rUTI) are a costly clinical problem affecting millions of women worldwide each year. The majority of rUTI cases are caused by uropathogenic Escherichia coli (UPEC). Data from humans and mouse models indicate that some instances of rUTI are caused by UPEC emerging from latent reservoirs in the bladder. Women with vaginal dysbiosis, typically characterized by high levels of Gardnerella and other anaerobes, are at increased risk of UTI. Multiple studies have detected Gardnerella in urine collected by transurethral catheterization (to limit vaginal contamination), suggesting that some women experience routine urinary tract exposures. We recently reported that inoculation of Gardnerella into the bladder triggers rUTI from UPEC bladder reservoirs in a mouse model. Here we performed whole bladder RNA-seq to identify host pathways involved in Gardnerella-induced rUTI. We identified a variety host pathways differentially expressed in whole bladders following Gardnerella exposure, such as pathways involved in inflammation/immunity and epithelial turnover. At the gene level, we identified upregulation of Immediate Early (IE) genes, which are induced in various cell types shortly following stimuli like infection and inflammation. One such upregulated IE gene was the orphan nuclear receptor Nur77 (aka Nr4a1). Pilot experiments in Nur77-/- mice suggest that Nur77 is necessary for Gardnerella exposure to trigger rUTI from UPEC reservoirs. These findings demonstrate that bladder gene expression can be impacted by short-lived exposures to urogenital bacteria and warrant future examination of responses in distinct cell types, such as with single cell transcriptomic technologies. The biological validation studies in Nur77-/- mice lay the groundwork for future studies investigating Nur77 and the Immediate Early response in rUTI.

Recurrent urinary tract infections in adults: a practical guide

Recurrent urinary tract infections are a common problem faced by clinicians across many specialities. For the patient, recurrent urinary tract infections can be burdensome and detrimental to their quality of life. For the clinician, they can be challenging to manage, and the socioeconomic burden on healthcare systems can also be substantial. Investigations serve to rule out any underlying structural or pathological abnormalities. In conjunction with behavioural prevention methods, treatment strategies include antibiotic and non-antibiotic approaches and holistic management approaches. This article provides an overview of the investigation and treatment of urinary tract infections and includes algorithms which can be used in daily clinical practice.

Bacterial Morphotypes as Important Trait for Uropathogenic E. coli Diagnostic; a Virulence-Phenotype-Phylogeny Study

Urinary tract infections (UTIs) belong to the most common pathologies in Mexico and are mainly caused by Uropathogenic Escherichia coli (UPEC). UPEC possesses a wide diversity of virulence factors that allow it to carry out its pathogenesis mechanism in the urinary tract (UT). The development of morphotypes in UT represents an important feature of UPEC because it is associated with complications in diagnosis of UTI. The aim of this study was to determine the presence of bacterial morphotypes, virulence genes, virulence phenotypes, antibiotic resistant, and phylogenetic groups in clinical isolates of UPEC obtained from women in Sonora, Mexico. Forty UPEC isolates were obtained, and urine morphotypes were observed in 65% of the urine samples from where E. coli was isolated. Phylogenetic group B2 was the most prevalent. The most frequent virulence genes were fimH (100%), fliCD (90%), and sfaD/focC (72%). Biofilm formation (100%) and motility (98%) were the most prevalent phenotypes. Clinical isolates showed high resistance to aminoglycosides and β-lactams antibiotics. These data suggest that the search for morphotypes in urine sediment must be incorporated in the urinalysis procedure and also that clinical isolates of UPEC in this study can cause upper, lower, and recurrent UTI.

Phage Therapy Related Microbial Succession Associated with Successful Clinical Outcome for a Recurrent Urinary Tract Infection

We rationally designed a bacteriophage cocktail to treat a 56-year-old male liver transplant patient with complex, recurrent prostate and urinary tract infections caused by an extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) (UCS1). We screened our library for phages that killed UCS1, with four promising candidates chosen for their virulence, mucolytic properties, and ability to reduce bacterial resistance. The patient received 2 weeks of intravenous phage cocktail with concomitant ertapenem for 6 weeks. Weekly serum and urine samples were collected to track the patient’s response. The patient tolerated the phage therapy without any adverse events with symptom resolution. The neutralization of the phage activity occurred with sera collected 1 to 4 weeks after the first phage treatment. This was consistent with immunoassays that detected the upregulation of immune stimulatory analytes. The patient developed asymptomatic recurrent bacteriuria 6 and 11 weeks following the end of phage therapy—a condition that did not require antibiotic treatment. The bacteriuria was caused by a sister strain of E. coli (UCS1.1) that remained susceptible to the original phage cocktail and possessed putative mutations in the proteins involved in adhesion and invasion compared to UCS1. This study highlights the utility of rationally designed phage cocktails with antibiotics at controlling E. coli infection and suggests that microbial succession, without complete eradication, may produce desirable clinical outcomes.

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.

Local Oral Delivery Agents with Anti-Biofilm Properties for the Treatment of Periodontitis and Peri-Implantitis. A Narrative Review

Despite many discoveries over the past 20 years regarding the etiopathogenesis of periodontal and peri-implant diseases, as well as significant advances in our understanding of microbial biofilms, the incidence of these pathologies continues to rise. For this reason, it was clear that other strategies were needed to eliminate biofilms. In this review, the literature database was searched for studies on locally delivered synthetic agents that exhibit anti-biofilm properties and their potential use in the treatment of two important oral diseases: periodontitis and peri-implantitis.

The use of intravesical hyaluronic acid in the management of symptomatic premenopausal women with pseudomembranous trigonitis: Are symptoms related to cystoscopy and pathological findings?

OBJECTIVES

To determine the effectiveness and safety of intravesical hyaluronic acid (HA) in symptomatic women with trigonitis and to correlate the severity of symptoms with the endoscopic and histological findings.

METHODS

Thirty-seven patients (aged 20-46 years) were enrolled. All patients had cystoscopy and biopsy of the bladder trigone followed by intravesical instillations of sodium HA once weekly for 10 weeks and then once monthly for the next 10 months. Clinical response was evaluated by Pain and Urgency/Frequency (PUF) Symptom Scale, visual analog scale (VAS) for pain and urgency and functional bladder capacity. A repeat cystoscopy and biopsy were performed at the end of the treatment. Symptoms and cystoscopy and pathological findings were compared before and after treatment.

RESULTS

The average initial score for pain was reduced from 5.5 to 2.8 (P < 0.001) at 10 weeks and further to 2.4 (P < 0.001) at 12 months and the score for urgency from 6.9 to 3.8 (P < 0.001) and further to 3.3 (P < 0.001). The average PUF score initially decreased from 20.5 to 12.1 (P < 0.001) and then further to 10.1 (P = 0.21). The mean functional bladder capacity increased from 125 to 204 mL (P < 0.001). No association was found between baseline PUF score and cystoscopy findings (P = 0.87). The PUF score was not changed significantly between patients with improved cystoscopy and those with stable findings (P = 0.74). No significant changes were reported between initial and final biopsies.

CONCLUSIONS

Intravesical HA appeared to be effective and well tolerated, although a clear relationship between symptoms and trigonitis was not confirmed.

Applications of bacteriophages against intracellular bacteria

Infectious diseases pose a significant threat to both human and animal populations. Intracellular bacteria are a group of pathogens that invade and survive within the interior of eukaryotic cells, which in turn protect them from antibacterial drugs and the host immune system. Limited penetration of antibacterials into host cells results in insufficient bacterial clearance and treatment failure. Bacteriophages have, over the decades, been proved to play an important role in combating bacterial infections (phage therapy), making them an important alternative to classical antibiotic strategies today. Phages have been found to be effective at killing various species of extracellular bacteria, but little is still known about how phages control intracellular infections. With advances in phage genomics and mechanisms of delivery and cell uptake, the development of phage-based antibacterial strategies to address the treatment of intracellular bacteria has general potential. In this review, we present the current state of knowledge regarding the application of bacteriophages against intracellular bacteria. We cover phage deployment against the most common intracellular pathogens with special attention to therapeutic and preventive strategies.

N-Acetylcysteine Protects Bladder Epithelial Cells from Bacterial Invasion and Displays Antibiofilm Activity against Urinary Tract Bacterial Pathogens

Introduction: Urinary tract infections (UTIs) affect more than 150 million individuals annually. A strong correlation exists between bladder epithelia invasion by uropathogenic bacteria and patients with recurrent UTIs. Intracellular bacteria often recolonise epithelial cells post-antibiotic treatment. We investigated whether N-acetylcysteine (NAC) could prevent uropathogenic E. coli and E. faecalis bladder cell invasion, in addition to its effect on uropathogens when used alone or in combination with ciprofloxacin. Methods: An invasion assay was performed in which bacteria were added to bladder epithelial cells (BECs) in presence of NAC and invasion was allowed to occur. Cells were washed with gentamicin, lysed, and plated for enumeration of the intracellular bacterial load. Cytotoxicity was evaluated by exposing BECs to various concentrations of NAC and quantifying the metabolic activity using resazurin at different exposure times. The effect of NAC on the preformed biofilms was also investigated by treating 48 h biofilms for 24 h and enumerating colony counts. Bacteria were stained with propidium iodide (PI) to measure membrane damage. Results: NAC completely inhibited BEC invasion by multiple E. coli and E. faecalis clinical strains in a dose-dependent manner (p < 0.01). This was also evident when bacterial invasion was visualised using GFP-tagged E. coli. NAC displayed no cytotoxicity against BECs despite its intrinsic acidity (pH ~2.6), with >90% cellular viability 48 h post-exposure. NAC also prevented biofilm formation by E. coli and E. faecalis and significantly reduced bacterial loads in 48 h biofilms when combined with ciprofloxacin. NAC visibly damaged E. coli and E. faecalis bacterial membranes, with a threefold increase in propidium iodide-stained cells following treatment (p < 0.05). Conclusions: NAC is a non-toxic, antibiofilm agent in vitro and can prevent cell invasion and IBC formation by uropathogens, thus providing a potentially novel and efficacious treatment for UTIs. When combined with an antibiotic, it may disrupt bacterial biofilms and eliminate residual bacteria.

One, No One and One Hundred Thousand: Patterns of chronic prostatic inflammation and infection

Chronic prostatic inflammation may be classified into three types that share similar symptoms and are distinguished on the basis of microbiological findings. In the present study, consecutive cases of chronic prostatic inflammation and infection were retrospectively reviewed in order to explore the clinical course and long-term outcomes. The cohort consisted of patients with symptoms of prostatitis who visited the Urology Clinic of the Tzaneion Hospital (Piraeus, Greece) between March 2009 and March 2019. The patients were subjected to the Meares and Stamey ‘4-glass’ test and patients with febrile prostatitis were evaluated with a single mid-stream ‘clean’ urine sample culture. Bacterial identification was performed using the Vitek 2 Compact system and the sensitivity test with the disc and the Vitek 2 system. A total of 656 patients with prostatitis-like symptoms with 1,783 visits for investigation and follow-up were reviewed and patients were divided into two major groups. Group 1 consisted of 549 cases with a single set of chronic prostatitis (CP)-like symptoms assessed in up to three visits. National Institutes of Health (NIH) category II CP (NIH-II) was most frequently diagnosed in those patients (37,6%). At the follow-up, 125 patients were identified as having a type of CP different from that determined initially. Group 2 (107 cases) had recurring episodes of prostatitis-like symptoms assessed or confirmed over the course of 4-18 visits. Most patients (54.2%) were initially diagnosed with NIH-II followed by disease-free periods and recurrence/reinfection or by shifts to NHI-IIIB. In conclusion, CP remains a poorly understood n medical condition characterized by a variety of clinical manifestations and by transitions between different CP classes during its course.

Dynamic persistence of UPEC intracellular bacterial communities in a human bladder-chip model of urinary tract infection

Uropathogenic Escherichia coli (UPEC) proliferate within superficial bladder umbrella cells to form intracellular bacterial communities (IBCs) during early stages of urinary tract infections. However, the dynamic responses of IBCs to host stresses and antibiotic therapy are difficult to assess in situ. We develop a human bladder-chip model wherein umbrella cells and bladder microvascular endothelial cells are co-cultured under flow in urine and nutritive media respectively, and bladder filling and voiding mimicked mechanically by application and release of linear strain. Using time-lapse microscopy, we show that rapid recruitment of neutrophils from the vascular channel to sites of infection leads to swarm and neutrophil extracellular trap formation but does not prevent IBC formation. Subsequently, we tracked bacterial growth dynamics in individual IBCs through two cycles of antibiotic administration interspersed with recovery periods which revealed that the elimination of bacteria within IBCs by the antibiotic was delayed, and in some instances, did not occur at all. During the recovery period, rapid proliferation in a significant fraction of IBCs reseeded new foci of infection through bacterial shedding and host cell exfoliation. These insights reinforce a dynamic role for IBCs as harbors of bacterial persistence, with significant consequences for non-compliance with antibiotic regimens.

Urinary tract infections are one of the most common reasons people need antibiotics. These bacterial infections are typically caused by uropathogenic Escherichia coli (also known as UPEC), which either float freely in the urine and wash away when the bladder empties, or form communities inside cells that the bladder struggles to clear. It is possible that the bacteria living within cells are also more protected from the immune system and antibiotics. But this is hard to study in animal models.

To overcome this, Sharma et al. built a ‘bladder-chip’ which mimics the interface between the blood vessels and the tissue layers of the human bladder. Similar chip devices have also been made for other organs. However, until now, no such model had been developed for the bladder.

On the chip created by Sharma et al. is a layer of bladder cells which sit at the bottom of a channel filled with diluted human urine. These cells were infected with UPEC, and then imaged over time to see how the bacteria moved, interacted with the bladder cells, and aggregated together. Immune cells from human blood were then added to a vascular channel underneath the bladder tissue, which is coated with endothelial cells that normally line blood vessels. The immune cells rapidly crossed the endothelial barrier and entered the bladder tissue, and swarmed around sites of infection. In some instances, they released the contents of their cells to form net-like traps to catch the bacteria. But these traps failed to remove the bacteria living inside bladder cells.

Antibiotics were then added to the urine flowing over the bladder cells as well as the vascular channel, similar to how drugs would be delivered in live human tissue. Sharma et al. discovered that the antibiotics killed bacteria residing in bladder cells slower than bacteria floating freely in the urine. Furthermore, they found that bacteria living in tightly packed communities within bladder cells were more likely to survive treatment and go on to re-infect other parts of the tissue.

Antibiotic resistance is a pressing global challenge, and recurrent urinary tract infections are a significant contributor. The bladder-chip presented here could further our understanding of how these bacterial infections develop in vivo and how good antibiotics are at removing them. This could help researchers identify the best dosing and treatment strategies, as well as provide a platform for rapidly testing new antibiotic drugs and other therapies.

Identification of essential genes for Escherichia coli aryl polyene biosynthesis and function in biofilm formation

Aryl polyenes (APEs) are specialized polyunsaturated carboxylic acids that were identified in silico as the product of the most widespread family of bacterial biosynthetic gene clusters (BGCs). They are present in several Gram-negative host-associated bacteria, including multidrug-resistant human pathogens. Here, we characterize a biological function of APEs, focusing on the BGC from a uropathogenic Escherichia coli (UPEC) strain. We first perform a genetic deletion analysis to identify the essential genes required for APE biosynthesis. Next, we show that APEs function as fitness factors that increase protection from oxidative stress and contribute to biofilm formation. Together, our study highlights key steps in the APE biosynthesis pathway that can be explored as potential drug targets for complementary strategies to reduce fitness and prevent biofilm formation of multi-drug resistant pathogens.

The microbiome and host mucosal interactions in urinary tract diseases

The urinary tract consists of the bladder, ureters, and kidneys, and is an essential organ system for filtration and excretion of waste products and maintaining systemic homeostasis. In this capacity, the urinary tract is impacted by its interactions with other mucosal sites, including the genitourinary and gastrointestinal systems. Each of these sites harbors diverse ecosystems of microbes termed the microbiota, that regulates complex interactions with the local and systemic immune system. It remains unclear whether changes in the microbiota and associated metabolites may be a consequence or a driver of urinary tract diseases. Here, we review the current literature, investigating the impact of the microbiota on the urinary tract in homeostasis and disease including urinary stones, acute kidney injury, chronic kidney disease, and urinary tract infection. We propose new avenues for exploration of the urinary microbiome using emerging technology and discuss the potential of microbiome-based medicine for urinary tract conditions.

A Novel Device-Integrated Drug Delivery System for Local Inhibition of Urinary Tract Infection

Background: Catheter-associated urinary tract infection (CAUTI) is a frequent community-acquired infection and the most common nosocomial infection. Here, we developed a novel antimicrobial catheter concept that utilizes a silicone-based interpenetrating polymer network (IPN) as balloon material to facilitate a topical slow-release prophylaxis of antibacterial agents across the balloon to the urinary bladder.

Methods: The balloon material was achieved by modifying low shore hardness silicone tubes with a hydrogel interpenetrating polymer in supercritical CO₂ using the sequential method. Release properties and antibacterial efficacy of the IPN balloon treatment concept was investigated in vitro and in a porcine CAUTI model developed for the study. In the latter, Bactiguard Infection Protection (BIP) Foley catheters were also assessed to enable benchmark with the traditional antimicrobial coating principle.

Results: Uropathogenic Escherichia coli was undetectable in urinary bladders and on retrieved catheters in the IPN treatment group as compared to control that revealed significant bacteriuria (>10⁵ colony forming units/ml) as well as catheter-associated biofilm. The BIP catheters failed to prevent E. coli colonization of the bladder but significantly reduced catheter biofilm formation compared to the control.

Conclusion: The IPN-catheter concept provides a novel, promising delivery route for local treatment in the urinary tract.

Urethral Catheter Biofilms Reveal Plasticity in Bacterial Composition and Metabolism and Withstand Host Immune Defenses in Hypoxic Environment

Biofilms composed of multiple microorganisms colonize the surfaces of indwelling urethral catheters that are used serially by neurogenic bladder patients and cause chronic infections. Well-adapted pathogens in this niche are Escherichia coli, Proteus, and Enterococcus spp., species that cycle through adhesion and multilayered cell growth, trigger host immune responses, are starved off nutrients, and then disperse. Viable microbial foci retained in the urinary tract recolonize catheter surfaces. The molecular adaptations of bacteria in catheter biofilms (CBs) are not well-understood, promising new insights into this pathology based on host and microbial meta-omics analyses from clinical specimens. We examined catheters from nine neurogenic bladder patients longitudinally over up to 6 months. Taxonomic analyses from 16S rRNA gene sequencing and liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based proteomics revealed that 95% of all catheter and corresponding urinary pellet (UP) samples contained bacteria. CB biomasses were dominated by Enterobacteriaceae spp. and often accompanied by lactic acid and anaerobic bacteria. Systemic antibiotic drug treatments of patients resulted in either transient or lasting microbial community perturbations. Neutrophil effector proteins were abundant not only in UP but also CB samples, indicating their penetration of biofilm surfaces. In the context of one patient who advanced to a kidney infection, Proteus mirabilis proteomic data suggested a combination of factors associated with this disease complication: CB biomasses were high; the bacteria produced urease alkalinizing the pH and triggering urinary salt deposition on luminal catheter surfaces; P. mirabilis utilized energy-producing respiratory systems more than in CBs from other patients. The NADH:quinone oxidoreductase II (Nqr), a Na+ translocating enzyme not operating as a proton pump, and the nitrate reductase A (Nar) equipped the pathogen with electron transport chains promoting growth under hypoxic conditions. Both P. mirabilis and E. coli featured repertoires of transition metal ion acquisition systems in response to human host-mediated iron and zinc sequestration. We discovered a new drug target, the Nqr respiratory system, whose deactivation may compromise P. mirabilis growth in a basic pH milieu. Animal models would not allow such molecular-level insights into polymicrobial biofilm metabolism and interactions because the complexity cannot be replicated.

Evolution of the Antimicrobial resistance of Bacteria causing Urinary Tract Infections

BACKGROUND

The bacteria, Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae), are the main reasons for urinary tract infections (UTIs). This research aimed to investigate the isolation of etiologic agents from patients with UTI; it also investigates the antibiotic resistance activities and incidence of ESBL genes between different clinical separates of uropathogenic E. coli, determining their association with ESBL genes.

METHODS

The study enrolled 1000 positive growth isolates. The predominant pathogen associated with urinary tract infection, Gram-negative, were the main isolates from UTI patients, including E. coli, K. pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus aureus and Enterococcus faecalis.

RESULTS

Among suspicious cases of urinary tract infection, we showed that 15.2% of the patients had UTI, and female patients in the childbearing age group were more affected. 644 E. coli (64.4%) and 322 (32.2%) K. pneumoniae were more isolated. Among 936 (93.6%) ESBL producing bacteria, 614 (61.4 %) E. coli showedhigh resistance to the antibiotics, Cefotaxime (85.7 %), Cefepime (85.7 %), Ciprofloxacin (83.1 %) and Kanamycin (77.9 %). Most ESBL-producing K. pneumoniae were multidrug-resistant (MDR). Nitrofurantoin, gentamycin, and imipenem were the most effective antibiotics for ESBL-producing E. coli isolates.

CONCLUSION

This study shows that the high rates of MDR Escherichia coli infection in our hospital were frequentative reasons for UTI. Nitrofurantoin and aminoglycosides were the most beneficial first-line drugs to be applied in the cases of UTI. It is recommended to conduct regular investigations on the drug resistance of all isolates and formulate helpful antibiotic treatment policies in China. It is important to determine the prevalence of ESBL in urine E. coli and K. pneumoniae isolates because it has a great influence on the selection of suitable antibacterial agents. In short, more than half of ESBL producers have multiple drug resistance (MDR).

Bacterial colonization of bladder urothelial cells in women with refractory Detrusor Overactivity: the effects of antibiotic therapy

Bacterial infection may have a pathophysiological role in refractory Detrusor Overactivity (DO). The aim of this study was to observe any impact of antibiotic therapy upon bacterial colonization of urothelial cells, and to determine whether a relationship existed between colonization and symptom severity. Mid-stream urine samples were collected as part of a clinical trial of antibiotics in women with refractory DO. Wright stained urothelial cells were categorized according to the degree of bacterial colonization as; 'clear' (free of bacteria), or as associated with bacteria that were 'adjacent' to the cell or 'intracellular' at low or high density. The average percentages were compared with routine microbiology cultures, over the 26 week trial, and with patient clinical outcome measures of DO severity. In patients receiving placebo, 'high-density intracellular bacteria' significantly increased during urinary tract infection (P = 0.0008). In antibiotic patients, 'clear' cells were more prevalent. Amoxicillin & Clavulanic Acid significantly decreased bacterial colonization within urothelial cells, suggesting that these antibiotics possess the greatest intracellular efficacy. 'High-density intracellular bacteria' positively correlated with symptom severity, measured by leakage on pad test (P = 0.014), leaks per day (P = 0.004), and voids per day (P = 0.005). Thus, by decreasing high density intracellular bacteria, antibiotic treatment may improve the refractory DO condition.

Staphylococcus saprophyticus From Clinical and Environmental Origins Have Distinct Biofilm Composition

Biofilm formation has been shown to be critical to the success of uropathogens. Although Staphylococcus saprophyticus is a common cause of urinary tract infections, its biofilm production capacity, composition, genetic basis, and origin are poorly understood. We investigated biofilm formation in a large and diverse collection of S. saprophyticus (n = 422). Biofilm matrix composition was assessed in representative strains (n = 63) belonging to two main S. saprophyticus lineages (G and S) recovered from human infection, colonization, and food-related environment using biofilm detachment approach. To identify factors that could be associated with biofilm formation and structure variation, we used a pangenome-wide association study approach. Almost all the isolates (91%; n = 384/422) produced biofilm. Among the 63 representative strains, we identified eight biofilm matrix phenotypes, but the most common were composed of protein or protein-extracellular DNA (eDNA)-polysaccharides (38%, 24/63 each). Biofilms containing protein-eDNA-polysaccharides were linked to lineage G and environmental isolates, whereas protein-based biofilms were produced by lineage S and infection isolates (p < 0.05). Putative biofilm-associated genes, namely, aas, atl, ebpS, uafA, sasF, sasD, sdrH, splE, sdrE, sdrC, sraP, and ica genes, were found with different frequencies (3-100%), but there was no correlation between their presence and biofilm production or matrix types. Notably, icaC_1 was ubiquitous in the collection, while icaR was lineage G-associated, and only four strains carried a complete ica gene cluster (icaADBCR) except one that was without icaR. We provided evidence, using a comparative genomic approach, that the complete icaADBCR cluster was acquired multiple times by S. saprophyticus and originated from other coagulase-negative staphylococci. Overall, the composition of S. saprophyticus biofilms was distinct in environmental and clinical isolates, suggesting that modulation of biofilm structure could be a key step in the pathogenicity of these bacteria. Moreover, biofilm production in S. saprophyticus is ica-independent, and the complete icaADBCR was acquired from other staphylococci.

Infección de vías urinarias no complicada en mujeres

La infección de vías urinarias (IVU) es una patología común, que afecta a gran parte de la población y que generalmente se resuelve con manejo antibiótico. Se compone de una amplia variedad de entidades clínicas que pueden variar desde una cistitis no complicada hasta un shock séptico de origen urinario. Los patógenos etiológicos de la IVU no complicada están ampliamente establecidos y se han mantenido de forma consistente a lo largo del tiempo, siendo la Escherichia coli el microorganismo más predominante. En la actualidad, la resistencia bacteriana a los antibióticos es de gran preocupación y por esa razón, se busca optimizar la terapia antimicrobiana con el fin de disminuir la estancia hospitalaria, la severidad clínica de la infección y los costos a los sistemas de salud. La presente revisión, tiene como objetivo servir como guía para la correcta definición, clasificación, diagnóstico, tratamiento y prevención de la IVU no complicada.

Recurrent Urinary Tract Infection: A Mystery in Search of Better Model Systems

Urinary tract infections (UTIs) are among the most common infectious diseases worldwide but are significantly understudied. Uropathogenic E. coli (UPEC) accounts for a significant proportion of UTI, but a large number of other species can infect the urinary tract, each of which will have unique host-pathogen interactions with the bladder environment. Given the substantial economic burden of UTI and its increasing antibiotic resistance, there is an urgent need to better understand UTI pathophysiology - especially its tendency to relapse and recur. Most models developed to date use murine infection; few human-relevant models exist. Of these, the majority of in vitro UTI models have utilized cells in static culture, but UTI needs to be studied in the context of the unique aspects of the bladder's biophysical environment (e.g., tissue architecture, urine, fluid flow, and stretch). In this review, we summarize the complexities of recurrent UTI, critically assess current infection models and discuss potential improvements. More advanced human cell-based in vitro models have the potential to enable a better understanding of the etiology of UTI disease and to provide a complementary platform alongside animals for drug screening and the search for better treatments.

What Is the Cause of Recurrent Urinary Tract Infection? Contemporary Microscopic Concepts of Pathophysiology

Urinary tract infections (UTIs) are the most common infectious disease and are mainly caused by Escherichia coli. In this review, we introduce the current concept of recurrent UTI (rUTI) based on recent research dealing with pathophysiology of the disease. Although urine is considered sterile, recent studies dealing with microbiome have proposed different ideas. UTIs have typically been considered as extracellular infections, but recently, uropathogenic Escherichia coli (UPEC) has been shown to bind and replicate in the urothelium to make intracellular bacterial communities. Binding UPECs might proceed in many ways including extracellular expulsion for clearance or survival and quiescent intracellular reservoirs that can cause rUTI. Moreover, it is also suggested that other important factors, such as lipopolysaccharide and multimicrobial infection, can be the cause of rUTI. This review article reveals a key mechanism of recurrence and discusses what makes a pathway of resolution or recurrence in a host after initial infection.

The glycobiology of uropathogenic E. coli infection: the sweet and bitter role of sugars in urinary tract immunity

Urinary tract infections (UTI) are among the most prevalent infectious diseases and the most common cause of nosocomial infections, worldwide. Uropathogenic E. coli (UPEC) are responsible for approximately 80% of all UTI, which most commonly affect the bladder. UPEC colonize the urinary tract by ascension of the urethra, followed by cell invasion, and proliferation inside and outside urothelial cells, thereby causing symptomatic infections and quiescent intracellular reservoirs that may lead to recurrence. Sugars, or glycans, are key molecules for host–pathogen interactions, and UTI are no exception. Surface glycans regulate many of the events associated with UPEC adhesion and infection, as well as induction of the host immune response. While the bacterial protein FimH binds mannose‐containing host glycoproteins to initiate infection and UPEC‐secreted polysaccharides block immune mechanisms to favour intracellular replication, host glycans on the urothelial surface and on secreted glycoproteins prevent or limit infection by inhibiting UPEC adhesion. Given the importance of glycans during UTI, here we review the glycobiology of UPEC infection to highlight fundamental sugar‐mediated processes of immunological interest for their potential clinical applications. Interdisciplinary approaches incorporating glycomics and infection biology may help to develop novel non‐antibiotic‐based therapeutic strategies for bacterial infections as the spread of antimicrobial‐resistant uropathogens is currently threatening modern healthcare systems.

Regulation of Expression of the TIR-Containing Protein C Gene of the Uropathogenic Escherichia coli Strain CFT073

The uropathogenic Escherichia coli strain CFT073 causes kidney abscesses in mice Toll/interleukin-1 receptor domain-containing protein C (TcpC) dependently and the corresponding gene is present in around 40% of E. coli isolates of pyelonephritis patients. It impairs the Toll-like receptor (TLR) signaling chain and the NACHT leucin-rich repeat PYD protein 3 inflammasome (NLRP3) by binding to TLR4 and myeloid differentiation factor 88 as well as to NLRP3 and caspase-1, respectively. Overexpression of the tcpC gene stopped replication of CFT073. Overexpression of several tcpC-truncation constructs revealed a transmembrane region, while its TIR domain induced filamentous bacteria. Based on these observations, we hypothesized that tcpC expression is presumably tightly controlled. We tested two putative promoters designated P1 and P2 located at 5′ of the gene c2397 and 5′ of the tcpC gene (c2398), respectively, which may form an operon. High pH and increasing glucose concentrations stimulated a P2 reporter construct that was considerably stronger than a P1 reporter construct, while increasing FeSO₄ concentrations suppressed their activity. Human urine activated P2, demonstrating that tcpC might be induced in the urinary tract of infected patients. We conclude that P2, consisting of a 240 bp region 5′ of the tcpC gene, represents the major regulator of tcpC expression.

Rapid Antimicrobial Susceptibility Testing on Clinical Urine Samples by Video-Based Object Scattering Intensity Detection

To combat the ongoing public health threat of antibiotic-resistant infections, a technology that can quickly identify infecting bacterial pathogens and concurrently perform antimicrobial susceptibility testing (AST) in point-of-care settings is needed. Here, we develop a technology for point-of-care AST with a low-magnification solution scattering imaging system and a real-time video-based object scattering intensity detection method. The low magnification (1-2×) optics provides sufficient volume for direct imaging of bacteria in urine samples, avoiding the time-consuming process of culture-based bacterial isolation and enrichment. Scattering intensity from moving bacteria and particles in the sample is obtained by subtracting both spatial and temporal background from a short video. The time profile of scattering intensity is correlated with the bacterial growth rate and bacterial response to antibiotic exposure. Compared to the image-based bacterial tracking and counting method we previously developed, this simple image processing algorithm accommodates a wider range of bacterial concentrations, simplifies sample preparation, and greatly reduces the computational cost of signal processing. Furthermore, development of this simplified processing algorithm eases implementation of multiplexed detection and allows real-time signal readout, which are essential for point-of-care AST applications. To establish the method, 130 clinical urine samples were tested, and the results demonstrated an accuracy of ∼92% within 60-90 min for UTI diagnosis. Rapid AST of 55 positive clinical samples revealed 98% categorical agreement with both the clinical culture results and the on-site parallel AST validation results. This technology provides opportunities for prompt infection diagnosis and accurate antibiotic prescriptions in point-of-care settings.

Dual transcriptional analysis reveals adaptation of host and pathogen to intracellular survival of Pseudomonas aeruginosa associated with urinary tract infection

Long-term survival of bacterial pathogens during persistent bacterial infections can be associated with antibiotic treatment failure and poses a serious public health problem. Infections caused by the Gram-negative pathogen Pseudomonas aeruginosa, which can cause both acute and chronic infections, are particularly challenging due to its high intrinsic resistance to antibiotics. The ineffectiveness of antibiotics is exacerbated when bacteria reside intracellularly within host cells where they can adopt a drug tolerant state. While the early steps of adherence and entry of P. aeruginosa into mammalian cells have been described, the subsequent fate of internalized bacteria, as well as host and bacterial molecular pathways facilitating bacterial long-term survival, are not well defined. In particular, long-term survival within bladder epithelial cells has not been demonstrated and this may have important implications for the understanding and treatment of UTIs caused by P. aeruginosa. Here, we demonstrate and characterize the intracellular survival of wild type (WT) P. aeruginosa inside bladder epithelial cells and a mutant with a disruption in the bacterial two-component regulator AlgR that is unable to survive intracellularly. Using simultaneous dual RNA-seq transcriptional profiling, we define the transcriptional response of intracellular bacteria and their corresponding invaded host cells. The bacterial transcriptional response demonstrates that WT bacteria rapidly adapt to the stress encountered in the intracellular environment in contrast to ΔalgR bacteria. Analysis of the host transcriptional response to invasion suggests that the NF-κB signaling pathway, previously shown to be required for extracellular bacterial clearance, is paradoxically also required for intracellular bacterial survival. Lastly, we demonstrate that intracellular survival is important for pathogenesis of P. aeruginosa in vivo using a model of murine urinary tract infection. We propose that the unappreciated ability of P. aeruginosa to survive intracellularly may play an important role in contributing to the chronicity and recurrence of P. aeruginosa in urinary tract infections.

Chronic persistent bacterial infections are a serious and growing public health problem worsened by the rise in antibiotic resistance, yet new approaches for treating these infections are lacking. These long-term infections can occur when bacteria invade and survive inside host cells where they can hide from the immune system and become less susceptible to killing by antibiotics. Pseudomonas aeruginosa, a bacterium conventionally considered an extracellular pathogen, can cause chronic infections of many organ systems, including the urinary tract. Here, we show that P. aeruginosa can in fact survive inside bladder epithelial cells and becomes tolerant to antibiotic treatment. Using gene expression analysis, we show that bacteria quickly adapt to the intracellular environment while the corresponding host cells upregulate the NF-κB signaling pathway. We demonstrate that this response, which had previously been shown to be required for clearance of extracellular bacteria, is paradoxically also required for survival of intracellular bacteria. We propose that the ability of P. aeruginosa to survive intracellularly plays an important role in contributing to the chronicity and recurrence of P. aeruginosa infections and that targeting host pathways, such as NF-κB signaling, could transform our ability to manage chronic and/or recurrent infections.