Preventing urinary tract infection: progress toward an effective Escherichia coli vaccine

Genomic and proteomic characterization of four novel Schitoviridae family phages targeting uropathogenic Escherichia coli strain

BACKGROUND

Escherichia coli-associated urinary tract infections (UTIs) are among the most prevalent bacterial infections in humans. Typically, antibiotic medication is used to treat UTIs, but over the time, growth of multidrug resistance among these bacteria has created a global public health issue that necessitates other treatment modalities, such as phage therapy.

METHODS

The UPEC strain PSU-5266 (UE-17) was isolated from human urine samples, while phages were obtained from wastewater. These phages were characterized through host range analysis, stability studies, adsorption assays, and electron microscopy. Additionally, genomic, phylogenetic, and proteomic analyses were conducted to provide further insights.

RESULTS

The current study describes the isolation and characterization of four Escherichia coli phages designated as UE-S5a, UE-S5b, UE-M3 and UE-M6. Bactericidal assays depicted that all bacteriophages exhibited a strong lytic ability against uropathogenic E. coli (UPEC) strain PSU-5266 (UE-17). The phages displayed a broad host range (31-41%) among 104 tested isolates and adsorption rate of 15-20 min. They were stable within pH range of 5-11 and temperature range of 4 to 55 °C. Electron microscopy showed that all phages have icosahedral heads (70-74 nm) and short non-contractile tails, thus exhibiting a podovirus morphology. Sequencing results showed that they have linear double stranded DNA, genome of 73 to 76 kb in length, with GC content of 42% and short direct terminal repeats. Their genomes contain 84-88 predicted genes with putative functions predicted to 42-48% of gene products. The phylogenetic and comparative genomic analysis results depicted that these phages, sharing > 98% sequence similarity, are new members of genus Gamaleyavirus of subfamily Enquatrovirinae, in the Schitoviridae family. Mass spectrometric analysis of purified phage particles identified 44-56 phage particle-associated proteins (PPAPs) belonging to various functional groups such as lysis proteins, structural proteins, DNA packaging related proteins, and proteins involved in replication, metabolism and regulation. In addition, no genes encoding virulence factors, antibiotic resistance or lysogeny factors were identified.

CONCLUSION

The overall findings suggest that these bacteriophages are potential candidates for phage therapy in treating UTIs caused by UPEC strains.

Structure-based design of an immunogenic, conformationally stabilized FimH antigen for a urinary tract infection vaccine

Adhesion of E. coli to the urinary tract epithelium is a critical step in establishing urinary tract infections. FimH is an adhesin positioned on the fimbrial tip which binds to mannosylated proteins on the urinary tract epithelium via its lectin domain (FimHLD). FimH is of interest as a target of vaccines to prevent urinary tract infections (UTI). Previously, difficulties in obtaining purified recombinant FimH from E. coli along with the poor inherent immunogenicity of FimH have hindered the development of effective FimH vaccine candidates. To overcome these challenges, we have devised a novel production method using mammalian cells to produce high yields of homogeneous FimH protein with comparable biochemical and immunogenic properties to FimH produced in E. coli. Next, to optimize conformational stability and immunogenicity of FimH, we used a computational approach to design improved FimH mutants and evaluated their biophysical and biochemical properties, and murine immunogenicity using a bacterial adhesion inhibition assay. This approach identified an immunogenic FimH variant (FimH-donor-strand complemented with FimG peptide 'triple mutant', FimH-DSG TM) capable of blocking bacterial adhesion that is produced at high yields in mammalian cells. By x-ray crystallography, we confirmed that the stabilized structure of the FimHLD in FimH-DSG TM is similar to native FimH on the fimbrial tip. Characterization of monoclonal antibodies elicited by FimH-DSG TM that can block bacterial binding to mannosylated surfaces identified 4 non-overlapping binding sites whose epitopes were mapped via a combinatorial cryogenic electron microscopy approach. Novel inhibitory epitopes in the lectin binding FimH were identified, revealing diverse functional mechanisms of FimH-directed antibodies with relevance to FimH-targeted UTI vaccines.

Urinary tract infections: pathogenesis, host susceptibility and emerging therapeutics

Urinary tract infections (UTIs), which include any infection of the urethra, bladder or kidneys, account for an estimated 400 million infections and billions of dollars in health-care spending per year. The most common bacterium implicated in UTI is uropathogenic Escherichia coli, but diverse pathogens including Klebsiella, Enterococcus, Pseudomonas, Staphylococcus and even yeast such as Candida species can also cause UTIs. UTIs occur in both women and men and in both healthy and immunocompromised patients. However, certain patient factors predispose to disease: for example, female sex, history of prior UTI, or the presence of a urinary catheter or other urinary tract abnormality. The current clinical paradigm for the treatment of UTIs involves the use of antibiotics. Unfortunately, the efficacy of this approach is dwindling as the prevalence of antimicrobial resistance rises among UTI isolates, and the immense quantity of antibiotics prescribed annually for these infections contributes to the emergence of resistant pathogens. Therefore, there is an urgent need for new antibiotics and non-antibiotic treatment and prevention strategies. In this Review, we discuss how recent studies of bacterial pathogenesis, recurrence, persistence, host-pathogen interactions and host susceptibility factors have elucidated new and promising targets for the treatment and prevention of UTIs.

Incidence and Recurrence of Urinary Tract Infections Caused by Uropathogenic Escherichia coli: A Retrospective Cohort Study

Purpose

Urinary tract infections (UTIs) are among the most common bacterial infections, with uropathogenic Escherichia coli (UPEC) as the main etiologic agent of uncomplicated UTIs (uUTIs). The prevalence of uUTis caused by organisms with antimicrobial resistance (AMR) is increasing worldwide, complexifying the disease management and increasing the risk of complications. In efforts to develop new strategies for uUTI prevention, it is imperative to understand factors associated with the occurrence of new episodes.

Patients and Methods

This retrospective cohort study aimed to assess the incidence of uUTIs caused by UPEC (UPEC-uUTIs) or unknown etiology (untested uUTIs) in adults aged ≥18 years receiving care in a San Francisco healthcare system.

Results

During 2014-2019, 1087 UPEC-uUTI and 4106 untested uUTI cases were documented, of which 324 (29.8%; 95% confidence interval: 27.1%-32.6%) and 1030 (25.1%; 95% confidence interval: 23.8%-26.4%) were followed by ≥1 new episode of uUTI within 12 months. In the UPEC-uUTI cohort, male gender, diagnosis of diabetes mellitus, and prior uUTI were risk factors for new episodes of uUTI. At the time of first UPEC-uUTI diagnosis, antimicrobial prescriptions were retrieved for 41.1% of cases. When tested, AMR was most frequently reported for trimethoprim/sulfamethoxazole or trimethoprim/sulfamethoxazole prescribed with other antimicrobials.

Conclusion

Our study provides important information on the incidence and risk of repeated episodes of uUTIs, as well as on AMR related to them.

Variability in Profiles and Prevalences of Gram-Negative Bacteria in Urinary Tract Infections: A Population-Based Analysis

Objective: An increase in antimicrobial resistance (AMR) is observed worldwide, partly due to the overuse and misuse of antibiotics, which are ineffective in certain population subgroups. This negatively impacts both the healthcare system and patients. Our study aimed to investigate the current AMR profiles for the most commonly used antibiotics in treating urinary tract infections (UTIs) caused by gram-negative bacteria (GNB) across different age and gender subpopulations. By doing so, we provide valuable information for doctors managing prophylactic and empiric therapeutic treatments. Materials and Methods: We retrospectively analysed over 650,000 urine cultures collected in the Microbiology Department of a referral university hospital in Southern England from January 2014 to December 2022. A population-based analysis for subgroups was performed to rule out differences in AMR patterns. Our report was recorded at UHS as an internal audit (UHS7670). Results: 146,867 cultures were found positive for GNB growth. Nitrofurantoin showed the best sensitivity patterns for all age subgroups (0.93% for patients aged ≤ 18; 1.22% for patients aged 19-40; 2.17% for patients aged 40-60; and 3.48% for patients aged > 60), regardless of gender (male: 6.37%, female: 2.59%). Ampicillin/amoxicillin and trimethoprim showed a poor AMR profile for all age groups (>55% and >28%, respectively) and genders (>60% and >28%, respectively). All the other tested antibiotics (cefalexin, cefotaxime, ceftazidime, ciprofloxacin, co-amoxiclav, gentamicin) showed an overall good profile for GNB resistance across all subgroups. For all antibiotics except trimethoprim, the risk of developing AMR was significantly higher in the male population. We also found that people aged over 60 had a higher risk of AMR compared to the other age groups for all antibiotics, with the exception of cefotaxime and co-amoxiclav. Conclusions: With an overall rise in resistance patterns for GNB-related UTIs, certain antibiotics-particularly ampicillin/amoxicillin and trimethoprim-now exhibit very poor sensitivity profiles. However, antibiotics such as nitrofurantoin and gentamicin remain excellent options for empirically treating UTIs. It is important to note that AMR can vary across different populations, with higher resistance often found in elderly and male patients. Clinicians must stay informed about current guidelines and research to provide the best treatment options while minimizing the risk of further AMR development.

Molecular characterization of ESBL-producing uropathogenic Escherichia coli isolates among kidney transplant patients: Emergence and spread of B2-ST131 clone type

This study was conducted to identify the distribution of virulence determinants in uropathogenic Escherichia coli (UPEC) isolates obtained from kidney transplant (KTP) and non-transplant patients (non-KTP) with urinary tract infections (UTI). Additionally, the (GTG)5 fingerprinting technique was used to investigate the genetic diversity of Extended-Spectrum B-Lactamase (ESBL)-positive isolates. In this case-control study, 111 urine isolates were obtained from non-KTPs and KTPs, respectively. The presence of genetic markers encoding adhesion proteins, toxins and major E. coli phylogroups was assessed through PCR amplification. Molecular typing of ESBL-positive UPEC strains was performed using (GTG)5 fingerprinting and Multilocus sequence typing (MLST) techniques. Overall, 65 and 46 UPEC isolates were obtained from non-KTPs and KTPs, respectively. Among the studied isolates, traT (85.6%) gene was the most frequently observed virulence gene, followed by kpsMT (49.5%). Using the 80% cut-off point, all the 35 UPEC isolates were classified into four major clusters, namely A, B, C, and D. The majority of the Sequence Type (ST) 131 isolates belonged to cluster A. Additionally, three ST1193 isolates belonged to cluster A and phylogroup B2. Moreover, ST38, ST131 and ST10 were in different cluster. In general, we observed significant differences in the papA, ompT, sat, and vat genes between KTPs and non-KTPs. Furthermore, since all the isolates carried one or more virulence factors (VFs), these findings are concerning in the context of managing UTIs caused by the UPEC strain. Additionally, the distribution of ST and Clonal Complex (CC) among isolates in the main clusters revealed significant differences between MLST and (GTG)5 fingerprinting analysis.

Raising the alarm: fosfomycin resistance associated with non-susceptible inner colonies imparts no fitness cost to the primary bacterial uropathogen

IMPORTANCE

While fosfomycin resistance is rare, the observation of non-susceptible subpopulations among clinical Escherichia coli isolates is a common phenomenon during antimicrobial susceptibility testing (AST) in American and European clinical labs. Previous evidence suggests that mutations eliciting this phenotype are of high biological cost to the pathogen during infection, leading to current recommendations of neglecting non-susceptible colonies during AST. Here, we report that the most common route to fosfomycin resistance, as well as novel routes described in this work, does not impair virulence in uropathogenic E. coli, the major cause of urinary tract infections, suggesting a re-evaluation of current susceptibility guidelines is warranted.

Vaccines against extraintestinal pathogenic Escherichia coli (ExPEC): progress and challenges

The emergence of antimicrobial resistance (AMR) is a principal global health crisis projected to cause 10 million deaths annually worldwide by 2050. While the Gram-negative bacteria Escherichia coli is commonly found as a commensal microbe in the human gut, some strains are dangerously pathogenic, contributing to the highest AMR-associated mortality. Strains of E. coli that can translocate from the gastrointestinal tract to distal sites, called extraintestinal E. coli (ExPEC), are particularly problematic and predominantly afflict women, the elderly, and immunocompromised populations. Despite nearly 40 years of clinical trials, there is still no vaccine against ExPEC. One reason for this is the remarkable diversity in the ExPEC pangenome across pathotypes, clades, and strains, with hundreds of genes associated with pathogenesis including toxins, adhesins, and nutrient acquisition systems. Further, ExPEC is intimately associated with human mucosal surfaces and has evolved creative strategies to avoid the immune system. This review summarizes previous and ongoing preclinical and clinical ExPEC vaccine research efforts to help identify key gaps in knowledge and remaining challenges.

From mucosal infection to successful cancer immunotherapy

The clinical management of advanced malignancies of the upper and lower urinary tract has been revolutionized with the advent of immune checkpoint blockers (ICBs). ICBs reinstate or bolster pre-existing immune responses while creating new T cell specificities. Immunogenic cancers, which tend to benefit more from immunotherapy than cold tumours, harbour tumour-specific neoantigens, often associated with a high tumour mutational burden, as well as CD8+ T cell infiltrates and ectopic lymphoid structures. The identification of beneficial non-self tumour antigens and natural adjuvants is the focus of current investigation. Moreover, growing evidence suggests that urinary or intestinal commensals, BCG and uropathogenic Escherichia coli influence long-term responses in patients with kidney or bladder cancer treated with ICBs. Bacteria infecting urothelium could be a prominent target for T follicular helper cells and B cells, linking innate and cognate CD8+ memory responses. In the urinary tract, commensal flora differ between healthy and tumoural mucosae. Although antibiotics can affect the prognosis of urinary tract malignancies, bacteria can have a major influence on cancer immunosurveillance. Beyond their role as biomarkers, immune responses against uropathogenic commensals could be harnessed for the design of future immunoadjuvants that can be advantageously combined with ICBs.

Immunoinformatics aided designing of a next generation poly-epitope vaccine against uropathogenic Escherichia coli to combat urinary tract infections

Urinary tract infections (UTIs) are the second most prevalent bacterial infections and uropathogenic Escherichia coli (UPEC) stands among the primary causative agents of UTIs. The usage of antibiotics is the routine therapy being used in various countries to treat UTIs but becoming ineffective because of increasing antibiotic resistance among UPEC strains. Thus, there must be the development of some alternative treatment strategies such as vaccine development against UPEC. In the following study, pan-genomics along with reverse vaccinology approaches is used under the framework of bioinformatics for the identification of core putative vaccine candidates, employing 307 UPEC genomes (complete and draft), available publicly. A total of nine T-cell epitopes (derived from B-cells) of both MHC classes (I and II), were prioritized among three potential protein candidates. These epitopes were then docked together by using linkers (GPGPG and AAY) and an adjuvant (Cholera Toxin B) to form a poly-valent vaccine construct. The chimeric vaccine construct was undergone by molecular modelling, further refinement and energy minimization. We predicted positive results of the vaccine construct in immune simulations with significantly high levels of immune cells. The protein-protein docking analysis of vaccine construct with toll-like receptors predicted efficient binding, which was further validated by molecular dynamics simulation of vaccine construct with TLR-2 and TLR-4 at 120 ns, resulting in stable complexes' conformation throughout the simulation run. Overall, the vaccine construct demonstrated positive antigenic response. In future, this chimeric vaccine construct or the identified epitopes could be experimentally validated for the development of UPEC vaccines against UTIs.Communicated by Ramaswamy H. Sarma.

Structural characterization, antioxidant and anti-uropathogenic potential of biogenic silver nanoparticles using brown seaweed Turbinaria ornata

Alternative treatment strategies for urinary tract infections (UTIs) are becoming more necessary due to increasing drug resistance patterns in uropathogens. Nanoparticle-based therapeutics is emerging as a way to treat UTIs. In the present study, using Turbinaria ornata extract, silver nanoparticles (AgNPs) were synthesized, characterized, and their anti-uropathogenic activity was evaluated. The stability and formation of synthesized To-AgNPs were confirmed by UV-visible spectroscopy, FTIR, XRD, SEM, and DLS. An FTIR spectrum confirmed the presence of seaweed functional groups in To-AgNPs, a XRD analysis confirmed their crystalline nature, and SEM imaging confirmed their spherical nature with an average size of 73.98 nm with diameters ranging from 64.67 to 81.28 nm. This was confirmed by TEM results. DLS determined that the cumulant hydrodynamic diameter of To-AgNPs was 128.3 nm with a PdI of 0.313 and the zeta potential value were found to be -63.3 mV which indicates the To-AgNPs are negatively charged and more stable. DPPH assays were used to assess the antioxidant activity of biosynthesized To-AgNPs, while an agar well diffusion method was used to test the antibacterial activity against uropathogens, including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, and Klebsiella pneumoniae. The To-AgNPs showed the highest susceptibility to S. aureus (15.75 ± 0.35 mm) and E. coli (15 ± 0.7 mm) with MIC values of 0.0625 and 0.125 mg/ml, respectively in macro broth dilution method and observed considerable membrane damage under CLSM and SEM. To-AgNPs displayed stronger antioxidant and antimicrobial activity, suggesting they may be developed as a new class of antimicrobial agents for treating UTIs.

Epidemiology and Antimicrobial Resistance Patterns of Urinary Tract Infections: A Cross-Sectional Study from Southwestern Saudi Arabia

Background: Urinary tract infections (UTIs) are a prevalent form of urinary tract diseases affecting individuals of all ages and genders. In the Kingdom of Saudi Arabia (KSA), UTIs are a significant burden on the healthcare system, comprising 10% of all infections and ranking as the second leading cause of emergency department admissions. Despite this, limited research has been conducted in Saudi Arabia, particularly in Jazan Province, located in the southwestern region. Methods: This retrospective, cross-sectional study encompassed individuals with positive urine cultures who sought care at a tertiary hospital in Jazan between January 2022 and March 2023. A standardized data collection form was utilized to retrieve relevant information from microbiology lab test results and patients' electronic medical records. Variables such as sex, urine sample collection date, bacterial isolates, antibiotic sensitivity, and resistance were collected using the data collection form. Data were analyzed using SPSS software, version 23.0 (IBM Corp., Armonk, NY, USA). Results: A total of 1082 urinary bacterial samples were isolated and identified. Females accounted for more bacterial infections (62.66%) than males (37.34%). Gram-negative bacteria represented 94% of all isolated strains. The most prevalent pathogens associated with UTIs were Escherichia coli (47.97%), Klebsiella pneumoniae (24.58%), and Pseudomonas aeruginosa (11.55%). Antimicrobial resistance patterns indicated the presence of extended-spectrum beta-lactamase (ESBL) (30.13%), carbapenemase-resistant Enterobacter (CRE) (1.94%), methicillin-resistant Staphylococcus aureus (MRSA) (0.74%), and vancomycin-resistant Enterococci (VRE) (0.18%). UTI incidence demonstrated a higher prevalence in September (13%) compared to other months in 2022. Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa were the predominant Gram-negative multidrug-resistant organisms (MDRO), accounting for 34.42%, 13.95%, and 1.63% of the population. Conclusions: The prevalence of UTIs caused by antibiotic-resistant microbes is notable in Jazan. Consistent with findings from other regions, Escherichia coli remains the most common causative pathogen of UTIs, displaying a seasonal pattern that warrants attention. Approximately 35% of reported cases involve MDRO, with ESBLs accounting for 30%. These results should raise concerns among healthcare officials, highlighting the necessity for further investigations into factors contributing to the circulation of MDRO in Jazan.

Specific Proteomic Identification of Collagen-Binding Proteins in Escherichia coli O157:H7: Characterisation of OmpA as a Potent Vaccine Antigen

Escherichia coli is a versatile commensal species of the animal gut that can also be a pathogen able to cause intestinal and extraintestinal infections. The plasticity of its genome has led to the evolution of pathogenic strains, which represent a threat to global health. Additionally, E. coli strains are major drivers of antibiotic resistance, highlighting the urgent need for new treatment and prevention measures. The antigenic and structural heterogeneity of enterohaemorrhagic E. coli colonisation factors has limited their use for the development of effective and cross-protective vaccines. However, the emergence of new strains that express virulence factors deriving from different E. coli diarrhoeagenic pathotypes suggests that a vaccine targeting conserved proteins could be a more effective approach. In this study, we conducted proteomics analysis and functional protein characterisation to identify a group of proteins potentially involved in the adhesion of E. coli O157:H7 to the extracellular matrix and intestinal epithelial cells. Among them, OmpA has been identified as a highly conserved and immunogenic antigen, playing a significant role in the adhesion phenotype of E. coli O157:H7 and in bacterial aggregation. Furthermore, antibodies raised against recombinant OmpA effectively reduced the adhesion of E. coli O157:H7 to intestinal epithelial cells. The present work highlights the role of OmpA as a potent antigen for the development of a vaccine against intestinal pathogenic E. coli.

In silico design and in vivo evaluation of two multi-epitope vaccines containing build-in adjuvant with chitosan nanoparticles against uropathogenic Escherichia coli

BACKGROUND

Urinary pathogenic Escherichia coli (UPEC) is one of the most important bacterial causes of urinary tract infections (UTIs). Rising antimicrobial resistance and serious clinical challenges such as persistent and recurrent UTIs make it a serious public health concern. Therefore, preventative approaches such as vaccinations are required.

METHODS

In this study, we selected three conserve and protective antigens (FdeC, Hma and UpaB) and also subunit B of cholera toxin (as build-in adjuvant) to design two multi-epitope vaccines (construct B containing B cell epitopes and construct T containing T epitopes) using different bioinformatics methods. The expression of the recombinant protein was performed using the BL21(DE3)/pET28 expression system and purified through a Ni-NTA column. Vaccine proteins were encapsulated in chitosan nanoparticles (CNP) based on ionic gelation via a microfluidic system. Mice were immunized intranasally with different vaccine formulations. Antibody responses and also cytokine expression (IFN-γ and IL-4) were measured by ELISA and real-time PCR respectively. The effectiveness of immune responses was assessed by bladder challenge.

RESULTS

Based on the in silico study, construct B and construct T have high confidence value and stable structure in vivo. High yield expression of both constructs was confirmed by SDS-PAGE and western blot assay. Immunization of mice with construct B induced strong Th2 (IgG1 and IL4) responses and construct T shift immune responses to Th1 (IFNγ and IgG2a). Vaccine protein-encapsulated CNP elicited higher levels of antibodies and cell-mediated responses than the vaccine proteins alone.

CONCLUSIONS

The results of this study suggest that intranasal administration of the construct B has the potential to enhance humoral immunity and construct T has the potential to stimulate cellular immunity. In addition, the combination of CTB as a build-in adjuvant and CNP can be proposed as a potent adjuvant for the development of a novel vaccine against UTI.

Glycoconjugate vaccines against antimicrobial resistant pathogens

INTRODUCTION

Antimicrobial resistance (AMR) is responsible for the death of millions worldwide and stands as a major threat to our healthcare systems, which are heavily reliant on antibiotics to fight bacterial infections. The development of vaccines against the main pathogens involved is urgently required as prevention remains essential against the rise of AMR.

AREAS COVERED

A systematic research review was conducted on MEDLINE database focusing on the six AMR pathogens defined as ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli), which are considered critical or high priority pathogens by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC). The analysis was intersecated with the terms carbohydrate, glycoconjugate, bioconjugate, glyconanoparticle, and multiple presenting antigen system vaccines.

EXPERT OPINION

Glycoconjugate vaccines have been successful in preventing meningitis and pneumoniae, and there are high expectations that they will play a key role in fighting AMR. We herein discuss the recent technological, preclinical, and clinical advances, as well as the challenges associated with the development of carbohydrate-based vaccines against leading AMR bacteria, with focus on the ESKAPE pathogens. The need of innovative clinical and regulatory approaches to tackle these targets is also highlighted.

Comparative analysis of outer membrane vesicles from uropathogenic Escherichia coli reveal the role of aromatic amino acids synthesis proteins in motility

Uropathogenic Escherichia coli (UPEC) are causative agent that causes urinary tract infections (UTIs) and the recent emergence of multidrug resistance (MDR) of UPEC increases the burden on the community. Recent studies of bacterial outer membrane vesicles (OMV) identified various factors including proteins, nucleic acids, and small molecules which provided inter-cellular communication within the bacterial population. However, the components of UPEC-specific OMVs and their functional role remain unclear. Here, we systematically determined the proteomes of UPEC-OMVs and identified the specific components that provide functions to the recipient bacteria. Based on the functional network of OMVs' proteomes, a group of signaling peptides was found in all OMVs which provide communication among bacteria. Moreover, we demonstrated that treatment with UPEC-OMVs affected the motility and biofilm formation of the recipient bacteria, and further identified aromatic amino acid (AAA) biosynthesis proteins as the key factors to provide their movement.

Design of a chimeric protein composed of FimH, FyuA and CNF-1 virulence factors from uropathogenic Escherichia coli and evaluation its biological activity and immunogenicity in vitro and in vivo

Urinary tract infections (UTIs) caused by Uropathogenic Escherichia coli (UPEC) are among the most prevalent bacterial infections in humans. Antibiotic resistance among UPEC isolates is increasing, and designing an effective vaccine can prevent or reduce these infections. FimH adhesin, iron scavenger receptor FyuA, and cytotoxic necrotizing factor -1 (CNF-1) are among the most important virulence factors of UPEC strains. Thus, a novel multi-epitope protein composed of FimH, FyuA, and CNF-1 was designed to evaluate its biological activity and immunogenicity in vitro and in vivo, respectively. The final vaccine design had seven domains, including the N-terminal domain of FimH, four domains of FyuA, and two domains of CNF-1, as determined by immunoinformatics analysis. The results of tertiary structure prediction showed that the chimeric protein had a C-score of -0.25 and Z-score of -1.94. Molecular docking indicated that thirty six ligand residues of the chimeric protein interacted with 53 receptor residues of TLR-4 by hydrogen bonds and hydrophobic interactions. Analysis of protein expression by SDS-PAGE showed an approximately 44 kDa band with different concentrations of IPTG which were confirmed by Western blot. According to ELISA results, the level of IL-8 produced by stimulated Ht29 cells with the chimeric protein was significantly higher than the stimulated Ht29 cells with CNF-1 alone and un-stimulated Ht29 cells. Rabbits subcutaneously immunized with the chimeric protein admixed with Freund adjuvant induced higher level of serum IgG on day 14 after the first vaccination than control rabbits. Furthermore, the booster dose of the chimeric protein significantly enhanced the IgG levels as compared to day 14 and also controls. As, the chimeric protein has suitable B-cell epitopes and MHC-I and MHC-II binding epitopes to stimulate humoral and cellular immunity, it could be a promising vaccine candidate against UTIs caused by UPEC. Evaluating the multi-epitope protein in inducing humoral and cellular immune responses, as well as protection, is ongoing in the mice models.

Clonal groups of extended-spectrum β-lactamase and biofilm producing uropathogenic Escherichia coli in Iran

Pathogenicity of a bacterium is affected by the social characteristics of the population and environmental factors. The ability of biofilm formation among β-lactamase-producing uropathogenic Escherichia coli (UPEC) could facilitate the exchange of antibiotic-resistance genes, which resulted in widespread dissemination of antibacterial drug resistance. We investigated the prevalence of biofilm and β-lactamase producing UPECs among patients with urinary tract infection (UTI) in two cities with different demographics and climates in Iran. A total of 265 E. coli was isolated from patients with UTIs from two referral hospitals (n = 191) and two outpatient clinics (n = 74) in Isfahan and Zahedan, Iran. Production of curli and cellulose, and, biofilm formation was investigated using Congo red agar and microtiter plate methods, respectively. Biofilm producing (BFP) isolates (n = 107) were further characterized using rep-PCR, antimicrobial susceptibility testing and extended-spectrum β-lactamase (ESBL)/AmpC phenotypic production. Isolates were also screened for the presence of carbapenemase, ESBL and AmpC genes using multiplex PCR.   High diversity was found among BFP strains in both cities, with 58% strains producing ESBL and 21% producing AmpC. ESBL (98%), AmpC (50%) and carbapenemase genes (40%) were identified in BFP strains with ESBL-positive phenotype, respectively. The prevalence of BFP strains, antibiotic resistance and β-lactamase genes in Zahedan, a low socioeconomic city with a warm climate, was significantly higher than that of Isfahan. High prevalence of biofilm and β-lactamase producing UPEC strains among strains from Zahedan suggests that socioeconomic status and environmental factors might have a role in pathogenicity of the strains.

Prevalence of Risk Factors of Urinary Tract Infections in Infants and Children in Arak, Iran: A Cross-sectional Study

Background: Urinary tract infection (UTI) is one of the most common childhood infections. Urinary tract infections are divided into simple and complex types. If the bladder infection is not treated, it can cause secondary kidney infections, such as acute pyelonephritis, which can lead to kidney scar or permanent kidney damage. A significant percentage of patients of any age are re-infected after antimicrobial treatments during the first six months after the first period of UTI. Objectives: This research aimed to investigate the risk factors affecting UTI in infants and children hospitalized in Arak Amir Kabir Hospital in 2017-2018 to prevent UTI and its secondary complications. Methods: In this cross-sectional study, the data collection tool was a validated questionnaire to gather the child's demographic characteristics, including age, sex, type of nutrition, circumcision, age of circumcision, as well as information about fetal birth weight, chronic maternal diseases such as diabetes and stress, and residence place. The content validation method was used to determine the validity of the checklist, and the test-retest was used for reliability. Data were analyzed by SPSS version 22 software. Results: Sixty four percent of children had the normal ultrasound, while 22% had hydronephrosis and nephrolithiasis on ultrasound. The average thickness and size of the right kidney were 71.75 and 9.11, and those of the left kidney were 9.11 and 9.50, respectively. The most common microorganism was Escherichia coli. Conclusions: Given the importance of prevention and timely diagnosis and treatment of UTI to prevent kidney injuries, it is necessary to find UTI risk factors as the first step to preventing children from secondary kidney injuries.

A sublingual nanofiber vaccine to prevent urinary tract infections

Urinary tract infections (UTIs) are a major public health problem affecting millions of individuals each year. Recurrent UTIs are managed by long-term antibiotic use, making the alarming rise of antibiotic resistance a substantial threat to future UTI treatment. Extended antibiotic regimens may also have adverse effects on the microbiome. Here, we report the use of a supramolecular vaccine to provide long-term protection against uropathogenic Escherichia coli, which cause 80% of uncomplicated UTIs. We designed mucus-penetrating peptide-polymer nanofibers to enable sublingual (under the tongue) vaccine delivery and elicit antibody responses systemically and in the urogenital tract. In a mouse model of UTI, we demonstrate equivalent efficacy to high-dose oral antibiotics but with significantly less perturbation of the gut microbiome. We also formulate our vaccine as a rapid-dissolving sublingual tablet that raises response in mice and rabbits. Our approach represents a promising alternative to antibiotics for the treatment and prevention of UTIs.

Genomics and pathotypes of the many faces of Escherichia coli

Escherichia coli is the most researched microbial organism in the world. Its varied impact on human health, consisting of commensalism, gastrointestinal disease, or extraintestinal pathologies, has generated a separation of the species into at least eleven pathotypes (also known as pathovars). These are broadly split into two groups, intestinal pathogenic E. coli (InPEC) and extraintestinal pathogenic E. coli (ExPEC). However, components of E. coli's infinite open accessory genome are horizontally transferred with substantial frequency, creating pathogenic hybrid strains that defy a clear pathotype designation. Here, we take a birds-eye view of the E. coli species, characterizing it from historical, clinical, and genetic perspectives. We examine the wide spectrum of human disease caused by E. coli, the genome content of the bacterium, and its propensity to acquire, exchange, and maintain antibiotic resistance genes and virulence traits. Our portrayal of the species also discusses elements that have shaped its overall population structure and summarizes the current state of vaccine development targeted at the most frequent E. coli pathovars. In our conclusions, we advocate streamlining efforts for clinical reporting of ExPEC, and emphasize the pathogenic potential that exists throughout the entire species.

Are Bacterial Persisters Dormant Cells Only?

Bacterial persisters are a sub-population of phenotypic variants that tolerate high concentrations of antibiotics within the genetically homogeneous cells. They resume division upon the removal of drugs. Bacterial persistence is one of major causes of antibiotic treatment failure and recurrent infection. Cell dormancy, triggered by toxin/antitoxin pair, (p)ppGpp, SOS response and ATP levels, is known to be the mechanistic basis for persistence. However, recent studies have demonstrated that bacteria with active metabolism can maintain persistence by lowering intracellular antibiotic concentration via an efflux pump. Additionally, others and our work have showed that cell wall deficient bacteria (CWDB), including both L-form and spheroplasts that produced by β-lactam antibiotics, are associated with antibiotic persistence. They are not dormant cells as their cell walls have been completely damaged. In this review, we discuss the various types of persisters and highlight the contribution of non-walled bacteria on bacterial persistence.

Whole-Person, Urobiome-Centric Therapy for Uncomplicated Urinary Tract Infection

A healthy urinary tract contains a variety of microbes resulting in a diverse urobiome. Urobiome dysbiosis, defined as an imbalance in the microbial composition in the microenvironments along the urinary tract, is found in women with uncomplicated urinary tract infection (UTI). Historically, antibiotics have been used to address UTI. An alternative approach to uncomplicated UTI is warranted as the current paradigm fails to take urobiome dysbiosis into account and contributes to the communal problem of resistance. A whole-person, multi-modal approach that addresses vaginal and urinary tract dysbiosis may be more effective in reducing recurrent UTI. In this review, we discuss strategies that include reducing pathogenic bacteria while supporting commensal urogenital bacteria, encouraging diuresis, maintaining optimal pH levels, and reducing inflammation. Strategies for future research are suggested.

Vaccination of mice with hybrid protein containing Exotoxin S and PcrV with adjuvants alum and MPL protects Pseudomonas aeruginosa infections

Pseudomonas aeruginosa as a common pathogen causing urinary tract infections (UTIs) has been resistant to different antibiotics and developing an effective vaccine can be an alternative strategy. In the present study, the immunogenicity and protection efficacy of formulations composed of a hybrid protein composed of P. aeruginosa V-antigen (PcrV) and exoenzyme S (ExoS) with alum and MPL were evaluated. The hybrid protein could increase the specific systemic and mucosal immune responses, as well as cellular responses as compared with control groups. Combining of alum or MPL adjuvant with the hybrid protein significantly improved the levels of IgG1, serum IgA, mucosal IgG, and IL-17 as compared to the ExoS.PcrV alone. After bladder challenge with a P. aeruginosa strain, the bacterial loads of bladder and kidneys were significantly decreased in mice received ExoS.PcrV admixed with alum and ExoS.PcrV admixed with MPL than controls. The present study indicated that immunization of mice with a hybrid protein composed of ExoS and PcrV could induce multifactorial immune responses and opsonize the bacteria and decrease the viable bacterial cells. Because P. aeruginosa have caused therapeutic challenges worldwide, our study proposed ExoS.PcrV + alum and ExoS.PcrV + MPL as promising candidates for the prevention of infections caused by P. aeruginosa.

Loss of an Intimin-Like Protein Encoded on a Uropathogenic E. coli Pathogenicity Island Reduces Inflammation and Affects Interactions with the Urothelium

Uropathogenic Escherichia coli (UPEC) causes the majority of uncomplicated urinary tract infections (UTI), which affect nearly half of women worldwide. Many UPEC strains encode an annotated intimin-like adhesin (ila) locus in their genome related to a well-characterized virulence factor in diarrheagenic E. coli pathotypes. Its role in UPEC uropathogenesis, however, remains unknown. In prototype UPEC strain CFT073, there is an ila locus that encodes three predicted intimin-like genes sinH, sinI, and ratA. We used in silico approaches to determine the phylogeny and genomic distribution of this locus among uropathogens. We found that the currently annotated intimin-encoding proteins in CFT073 are more closely related to invasin proteins found in Salmonella. Deletion of the individual sinH, sinI, and ratA genes did not result in measurable effects on growth, biofilm formation, or motility in vitro. On average, sinH was more highly expressed in clinical strains during active human UTI than in human urine ex vivo. Unexpectedly, we found that strains lacking this ila locus had increased adherence to bladder cells in vitro, coupled with a decrease in bladder cell invasion and death. The sinH mutant displayed a significant fitness defect in the murine model of ascending UTI including reduced inflammation in the bladder. These data confirmed an inhibitory role in bladder cell adherence to facilitate invasion and inflammation; therefore, the ila locus should be termed invasin-like, rather than intimin-like. Collectively, our data suggest that loss of this locus mediates measurable interactions with bladder cells in vitro and contributes to fitness during UTI.

The urobiome, urinary tract infections, and the need for alternative therapeutics

Improvements in bacterial culturing and DNA sequencing techniques have revealed a diverse, and hitherto unknown, urinary tract microbiome (urobiome). The potential role of this microbial community in contributing to health and disease, particularly in the context of urinary tract infections (UTIs) is of significant clinical importance. However, while several studies have confirmed the existence of a core urobiome, the role of its constituent microbes is not yet fully understood, particularly in the context of health and disease. Herein, we review the current state of the art, concluding that the urobiome represents an important component of the body's innate immune defences, and a potentially rich resource for the development of alternative treatment and control strategies for UTIs.

Differences of virulence factors, and antimicrobial susceptibility according to phylogenetic group in uropathogenic Escherichia coli strains isolated from Korean patients

Background

Escherichia coli is among the most common uropathogens. Increased antibiotic resistance in Gram negative bacilli is global concern. Alternative therapeutic options including vaccines against uropathogenic E. coli (UPEC) have been developed. In this study, we compared the genotypic characteristics and antimicrobial susceptibility of UPEC according to phylogenetic groups.

Methods

We retrospectively reviewed the medical records of pyelonephritis patients with UPEC between February 2015 and June 2018. The study was conducted at a medical center in Korea. We compared the clinical and genotypic characteristics of UPEC according to phylogenetic groups. The phylogenetic groups and 29 virulence factors were identified using multiplex polymerase chain reaction.

Results

Phylogenetic group analysis revealed that most uropathogenic E. coli belonged to groups B2 and D: B2 (276, 77.7%), D (62, 17.5%), B1 (12, 3.4%), and A (5, 1.4%). Among the virulence factors, fyuA, fimH, traT, iutA, papG allele II, and papC were the most frequently observed. Phylogenetic group B2 was more closely related to virulence factors, including fimH, sfa/focED, focG, hlyA, cnf1, fyuA, and PAI, than group D. Groups B2 and D showed similar clinical presentations and complications. Group B2 had mostly healthcare-associated infections and antimicrobial resistance. Group D mostly had community-acquired infections. The K1 serotype was prevalent in group B2, and K5 was the most prevalent in group D.

Conclusions

Phylogenetic group B2 had more proportions and types of virulence factors than group D. Group B2 showed a high presentation of virulence factors related to adhesions and toxins. An increased presentation of antimicrobial resistance and healthcare-associated infections was also noted. Considering the genetic characteristics of UPEC, alternative therapeutic options targeting frequent virulence factors might be considered in addition to antibiotics.

Characterization of PACs profile and bioactivity of a novel nutraceutical combining cranberry extracts with different PAC-A oligomers, D-mannose and ascorbic acid: An in vivo/ex vivo evaluation of dual mechanism of action on intestinal barrier and urinary epithelium

In this paper, an A-type procyanidin (PAC)-rich cranberry extract (CB-B) was obtained mixing different extracts and was formulated with D-mannose and ascorbic acid to obtain a novel nutraceutical (URO-F) aimed at preventing non-complicated bacterial urinary tract infections (UTIs). To assess the bioactivity of CB-B and URO-F, urine samples collected from six healthy volunteers undergoing a 2-days oral consumption of 0.41 g/day of CB-B or 10 g/day of URO-F (corresponding to 72 mg/day of PACs) were tested against uropathogenic E. coli (UPEC) incubated on urinary bladder epithelial cells (T24). Urinary markers of CB-B and URO-F consumption were assessed in the same urine output by UPLC-QTOF-based untargeted metabolomics approach. CB-B and URO-F were evaluated for their ability to promote the intestinal barrier function by restoring the trans-epithelial electrical resistance (TEER) and to inhibit the production of inflammatory cytokines in intestinal epithelial Caco2 cells. CB-B was characterized by a high PAC-A content (70% of total PACs) and a broad distribution of different PACs polymers (dimers-hexamers). Urine from subjects consuming CB-B and URO-F showed a significant effect in reducing the adhesion of UPEC to urothelium in vitro, supporting their efficacy as anti-adhesive agents after oral intake. CB-B inhibited the release of cytokine IL-8, and both products were effective in restoring the TEER. Overall, our results show that the beneficial effects of CB-B and URO-F on UTIs are not only due to the antiadhesive activity of cranberry on UPEC in the urothelium, but also to a multi-target activity involving anti-inflammatory and permeability-enhancing effects on intestinal epithelium.

Nanotechnologies for the delivery of biologicals: Historical perspective and current landscape

Biological macromolecule-based therapeutics irrupted in the pharmaceutical scene generating a great hope due to their outstanding specificity and potency. However, given their susceptibility to degradation and limited capacity to overcome biological barriers new delivery technologies had to be developed for them to reach their targets. This review aims at analyzing the historical seminal advances that shaped the development of the protein/peptide delivery field, along with the emerging technologies on the lead of the current landscape. Particularly, focus is made on technologies with a potential for transmucosal systemic delivery of protein/peptide drugs, followed by approaches for the delivery of antigens as new vaccination strategies, and formulations of biological drugs in oncology, with special emphasis on mAbs. Finally, a discussion of the key challenges the field is facing, along with an overview of prospective advances are provided.

Prospective Study in Children with Complicated Urinary Tract Infection Treated with Autologous Bacterial Lysates

Antimicrobial bacteria resistance is an important problem in children with recurrent urinary tract infections (rUTI), thus it is crucial to search for alternative therapies. Autologous bacterial lysates (ABL) may be a potential treatment for rUTI. Twenty-seven children with rUTI were evaluated for one year, urine and stool cultures were performed, 10 colonies of each culture were selected and those identified as Escherichia coli were characterized by serology. For patients who presented ≥105 UFC/mL, an ABL was manufactured and administered orally (1 mL/day) for a month. Twelve children were monitored for ≥1-year, 218 urine and 11 stool samples were analyzed. E. coli (80.5%) was the main bacteria isolated from urine and feces (72%). E. coli of classical urinary serotypes (UPEC), O25:H4, O75:HNM, and O9:HNM were identified in patients with persistent urinary infection (pUTI). In 54% of patients treated with ABL, the absence of bacteria was observed in urine samples after 3 months of treatment, 42% of these remained without UTI between 10-12 months. It was observed that the use of ABL controlled the infection for almost 1 year in more than 60% of the children. We consider it necessary to develop a polyvalent immunogen for the treatment and control of rUTI.

Local induction of bladder Th1 responses to combat urinary tract infections

Given the high frequency of urinary tract infections (UTIs) and their recurrence, there is keen interest in developing effective UTI vaccines. Currently, most vaccine studies, including those in humans, involve parenteral vaccination aimed at evoking and sustaining elevated levels of systemic antibody directed at the uropathogens. In view of recent reports of aberrant Th2-biased bladder immune responses to infection, we hypothesized that immunizing mice intravesically with antigens from uropathogenic Escherichia coli (UPEC) combined with a Th1-skewing adjuvant could correct this defect and promote protection against UTIs. Here we report that compared with mice immunized subcutaneously with this vaccine combination, intravesically immunized mice were markedly more protected from UTIs because of their distinctive ability to recruit Th1 cells into the bladder. This mode of vaccination was effective even in mice that experienced multiple UTIs and displayed pronounced aberrant bladder immune responses. Thus, intravesical vaccination with one or more UPEC antigens to induce bladder Th1 responses represents a superior strategy to combat UTIs, especially in UTI-prone subjects.

A Review of Plant-Based Therapies for the Treatment of Urinary Tract Infections in Traditional Southern African Medicine

Urinary tract infections (UTIs) are amongst the most common bacterial infections globally, with ∼11% of the world's population contracting at least one infection annually. Several South African plants are used in traditional healing systems to treat UTIs, yet the therapeutic potential of these plants against bacteria that cause UTI remains poorly explored. This study documents southern African plant species used traditionally to treat UTIs. An extensive literature review was undertaken to document the southern African plant species that are used in traditional South African medicine to treat UTIs, thereby highlighting gaps in the current research that require further study. One hundred and fifty-three southern African plant species that are used to treat UTIs were identified. Eighty-five southern African plants were identified as having noteworthy inhibitory activity against the major UTI-causing bacteria. Few of those studies screened against all of the bacterial causes of UTIs, and none of those studies examined the mechanism of action of the plant preparations. Furthermore, many of those studies did not test the toxicity of the plant extracts, so an evaluation of the safety for therapeutic usage was lacking. Substantial further research is to determine their potential for therapeutic use.

Comparative Pathogenomics of Escherichia coli: Polyvalent Vaccine Target Identification through Virulome Analysis

Comparative genomics of bacterial pathogens has been useful for revealing potential virulence factors. Escherichia coli is a significant cause of human morbidity and mortality worldwide but can also exist as a commensal in the human gastrointestinal tract. With many sequenced genomes, it has served as a model organism for comparative genomic studies to understand the link between genetic content and potential for virulence. To date, however, no comprehensive analysis of its complete “virulome” has been performed for the purpose of identifying universal or pathotype-specific targets for vaccine development. Here, we describe the construction of a pathotype database of 107 well-characterized completely sequenced pathogenic and nonpathogenic E. coli strains, which we annotated for major virulence factors (VFs). The data are cross referenced for patterns against pathotype, phylogroup, and sequence type, and the results were verified against all 1,348 complete E. coli chromosomes in the NCBI RefSeq database. Our results demonstrate that phylogroup drives many of the “pathotype-associated” VFs, and ExPEC-associated VFs are found predominantly within the B2/D/F/G phylogenetic clade, suggesting that these phylogroups are better adapted to infect human hosts. Finally, we used this information to propose polyvalent vaccine targets with specificity toward extraintestinal strains, targeting key invasive strategies, including immune evasion (group 2 capsule), iron acquisition (FyuA, IutA, and Sit), adherence (SinH, Afa, Pap, Sfa, and Iha), and toxins (Usp, Sat, Vat, Cdt, Cnf1, and HlyA). While many of these targets have been proposed before, this work is the first to examine their pathotype and phylogroup distribution and how they may be targeted together to prevent disease.

The current state of immunization against Gram-negative bacteria in children: a review of the literature

PURPOSE OF REVIEW

Gram-negative bacteria (GNB) are a major cause of infection worldwide and multidrug resistance in infants and children. The major pathogens include Klebsiella pneumoniae, Escherichia coli, Enterobacter spp., Pseudomonas aeruginosa and Acinetobacter baumannii. With new antibiotic options limited, immunization is likely to play a critical role in prevention. This review discusses their epidemiology, the current state of vaccine research and potential immunization strategies to protect children. A comprehensive review of the literature, conference abstracts along with web searches was performed to identify current and investigational vaccines against the major GNB in children.

RECENT FINDINGS

Phase I--III vaccine trials have been undertaken for the major Gram-negative bacteria but not in infants or children. E. coli is a common infection in immune-competent children, including neonatal sepsis. Several vaccines are in late-phase clinical trials, with some already licensed for recurrent urinary tract infections in women. Klebsiella spp. causes community-acquired and hospital-acquired infections, including sepsis in neonates and immunocompromised children although no vaccine trials have extended beyond early phase 2 trials. P. aeruginosa is a common pathogen in patients with cystic fibrosis. Phase 1--3 vaccine and monoclonal antibody trials are in progress, although candidates provide limited coverage against pathogenic strains. Enterobacter spp. and A. baumannii largely cause hospital-acquired infections with experimental vaccines limited to phase 1 research.

SUMMARY

The current immunization pipelines for the most prevalent GNB are years away from licensure. Similar to incentives for new antibiotics, global efforts are warranted to expedite the development of effective vaccines.

Immunization with recombinant protein Ag43::UpaH with alum and 1,25(OH)2D3 adjuvants significantly protects Balb/C mice against urinary tract infection caused by uropathogenic Escherichia coli

The majority of urinary tract infections (UTIs) are caused by uropathogenic Escherichia coli (UPEC). Designing a vaccine will certainly reduce the occurrence of infection and antibiotic resistance of the isolates. Antigen 43 (Ag43) and autotransporter H (UpaH) have been associated with the virulence of UPEC. In the present study, the efficacy of different formulations of a hybrid protein composed of Ag43 and UpaH with and without alum and 1,25(OH)2D3 (Vitamin D3) adjuvants were evaluated in mice model. A significant increase in IgG and cellular responses was developed against Ag43::UpaH as compared to the control mice. The addition of alum or a mixture of alum and Vitamin D3 to the protein significantly enhanced the serum IgG responses and tended to remain in a steady state until 6 months. In addition, the mentioned formulations produced significant amounts of IgG1, IL-4, and IL-17 as compared to the fusion protein alone. In addition to the mentioned formulations, the combination of protein with Vitamin D3 also resulted in significantly higher serum IgA and IFN-γ levels as compared to the fusion protein alone. Mice immunized with fusion plus alum and formulation protein admixed with both alum and Vitamin D3 significantly reduced the bacterial load in the bladders and kidneys of mice as compared to the control. In this study, for the first time, the ability of a novel hybrid protein in combination with adjuvants alum and Vitamin D3 was evaluated against UPEC. Our results indicated that fusion Ag43::UpaH admixed with alum and Vitamin D3 could be a promising candidate against UTIs.

Urinary Microbiome Characteristics in Female Patients with Acute Uncomplicated Cystitis and Recurrent Cystitis

Traditionally, the diagnostic mainstay of recurrent urinary tract infection has been urinary culture. However, the causative uropathogen of recurrent cystitis has not been well established. Urine DNA next-generation sequencing (NGS) can provide additional information on these infections. Herein, we compared urine NGS results and urine cultures in patients with acute uncomplicated cystitis (AUC) and recurrent cystitis (RC), and evaluated the difference in microbiome patterns in the NGS results. Patients who underwent urine culture and NGS due to AUC or RC were retrospectively reviewed. All urine samples were collected via a transurethral catheter and studied utilizing a type of NGS called 16S ribosomal RNA gene amplification and sequencing. The sensitivity of urine NGS was significantly higher than that of conventional urine culture (69.0% vs. 16.7%, p < 0.05). The detection rate of urine NGS was slightly lower in the RC group than in the AUC group (67.7% vs. 72.7%). Microbiome diversity was significantly higher in the RC group compared to the AUC group (p = 0.007), and the microbiome composition was significantly different between the AUC and RC groups. In the urine NGS results, Pseudomonas, Acinetobacter, and Enterobacteriaceae were found in the AUC group, and Sphingomonas, Staphylococcus, Streptococcus, and Rothia spp. were detected in the RC group. Urine NGS can significantly increase the diagnostic sensitivity compared to traditional urine culture methods, especially in RC patients. AUC and RC patients had significant differences in bacterial diversity and patterns. Therefore, recurrent cystitis might be approached from a different perspective.

In silico analysis and in vivo assessment of a novel epitope-based vaccine candidate against uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) are common pathogens in urinary tract infections (UTIs), which show resistance to antibiotics. Therefore, there is a need for a vaccine to reduce susceptibility to the infection. In the present study, bioinformatics approaches were employed to predict the best B and T-cell epitopes of UPEC virulence proteins to develop a multiepitope vaccine candidate against UPEC. Then, the efficacy of the candidate was studied with and without Freund adjuvant. Using bioinformatics methods, 3 epitope-rich domains of IutA and FimH antigens were selected to construct the fusion. Molecular docking and Molecular dynamics (MD) simulation were employed to investigate in silico interaction between designed vaccine and Toll-like receptor 4 (TLR4). Our results showed that the levels of IgG and IgA antibodies were improved in the serum and mucosal samples of the vaccinated mice, and the IgG responses were maintained for at least 6 months. The fusion protein was also able to enhance the level of cytokines IFN.γ (Th1), IL.4 (Th2), and IL.17. In challenge experiments, all vaccine combinations showed high potency in the protection of the urinary tract even after 6 months post first injection. The present study indicates that the designed candidate is able to evoke strong protective responses which warrant further studies.

Immunology of urinary tract infections

The urinary tract is constantly exposed to different microorganisms that colonize the gastrointestinal tract and the urinary tract is normally well prepared to resist infections by these microorganisms. This resistance to infection is mainly accomplished by the versatility of the immune system in the urinary tract, with both innate and adaptive immune responses. With the increasing knowledge of how the immune system works in the urinary tract and also the recognition of the virulence attributes of uropathogens, several potentially effective and tailored strategies to contain or prevent urinary tract infections have emerged.

[Bacterial urinary tract infection and subclinical bacteriuria in the dog: a current review]

Bacterial urinary tract infection (UTI) is a common clinical presentation in dogs and a frequent reason for the prescription of antimicrobial drugs. UTI refers to adherence, multiplication and persistence of an infectious agent within the urogenital system. This causes an associated inflammatory response as well as the pertaining clinical signs. Depending on the site of infection, UTI's may be classified as bacterial cystitis, prostatitis or pyelonephritis. In contrast, subclinical bacteriuria (SB) is defined as the presence of a significant number of bacteria in the urine of an individual not showing clinical signs referrable to UTI. UTI's typically occur as a consequence of ascending pathogen migration from the host's own fecal or distal urogenital microbial flora. The most commonly isolated pathogen in cases of UTI and SB is Escherichia coli. The diagnosis is based on clinical signs and the results of urine examination and culture. The recently revised guidelines of the International Society for Companion Animal Infectious Diseases provide detailed recommendations for diagnosis and management of different forms of bacterial UTI's in dogs. Adherence to treatment guidelines will improve treatment success and is imperative in avoiding further deterioration of the antimicrobial resistance situation.

The immune response to infection in the bladder

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

Characterization of Escherichia coli isolates potentially covered by ExPEC4V and ExPEC10V, that were collected from post-transrectal ultrasound-guided prostate needle biopsy invasive urinary tract and bloodstream infections

There is an increasing incidence of infectious complications caused by extraintestinal pathogenic Escherichia coli (ExPEC) after transrectal ultrasound-guided prostate needle biopsy (TRUS-PNB), and a need for prophylaxis methods effective against associated antibiotic-resistant organisms. We aimed to identify the O-serotypes of ExPEC isolates collected in a sample of 60 patients with invasive ExPEC disease (IED) after TRUS-PNB, by serotype-specific agglutination and polymerase chain reaction (PCR) assays. The prevalence of O-serotypes included in a tetravalent ExPEC vaccine was 38.3% by agglutination and 46.7% by PCR, while the prevalence of O-serotypes included in a decavalent vaccine was 58.3% and 73.3%, respectively. Therefore, compared to the tetravalent vaccine, the decavalent vaccine would theoretically provide coverage for serotypes carried by a higher proportion of circulating ExPEC in patients undergoing TRUS-PNB, including a high proportion of antibiotic-resistant organisms.

PapG subtype-specific binding characteristics of Escherichia coli towards globo-series glycosphingolipids of human kidney and bladder uroepithelial cells

Uropathogenic Escherichia coli (UPEC) are the primary cause of urinary tract infections (UTIs) in humans. P-fimbriae are key players for bacterial adherence to the uroepithelium through the Galα1-4Gal-binding PapG adhesin. The three identified classes I, II and III of PapG are supposed to adhere differently to host cell glycosphingolipids (GSLs) of the uroepithelial tract harboring a distal or internal Galα1-4Gal sequence. In this study, GSL binding characteristics were obtained in a nonradioactive adhesion assay using biotinylated E. coli UTI and urine isolates combined with enzyme-linked NeutrAvidin for detection. Initial experiments with reference globotriaosylceramide (Gb3Cer, Galα1-4Galβ1-4Glcβ1-1Cer), globotetraosylceramide (Gb4Cer, GalNAcβ1-3Galα1-4Galβ1-4Glcβ1-1Cer) and Forssman GSL (GalNAcα1-3GalNAcβ1-3Galα1-4Galβ1-4Glcβ1-1Cer) revealed balanced adhesion toward the three GSLs for PapG I-mediated attachment. In contrast, E. coli carrying PapG II or PapG III increasingly adhered to growing oligosaccharide chain lengths of Gb3Cer, Gb4Cer and Forssman GSL. Binding studies with GSLs from human A498 kidney and human T24 bladder epithelial cells, both being negative for the Forssman GSL, revealed the less abundant Gb4Cer vs. Gb3Cer as the prevalent receptor in A498 cells of E. coli expressing PapG II or PapG III. On the other hand, T24 cells exhibited a higher relative content of Gb4Cer vs. Gb3Cer alongside dominant binding of PapG II- or PapG III-harboring E. coli toward Gb4Cer and vastly lowered attachment to minor Gb3Cer. Further studies on PapG-mediated interaction with cell surface-exposed GSLs will improve our knowledge on the molecular mechanisms of P-fimbriae-mediated adhesion and may contribute to the development of antiadhesion therapeutics to combat UTIs.

Intramuscular Immunization Induces Antigen-specific Antibodies in Urine

Towards the development of vaccines against urinary tract infections (UTI), we determined the ability of intramuscular (i.m.) immunization to result in antigen-specific antibodies in urine. As a model antigen/vaccine, levels of total and vaccine-specific antibodies were determined in urine as a spin-out study of a phase 1 trial. Non-muscle-invasive bladder cancer (NMIBC) patients at different risks of progression, undergoing intravesical bacillus Calmette-Guérin (BCG) immunotherapy or not, received an adjuvanted recombinant protein vaccine that resulted in high titers of vaccine-specific serum immunoglobulin G (IgG) in all patients, regardless of the risk group. Vaccine-specific IgG and immunoglobulin A (IgA) were detected in urine of half of the patients at low risk of progression NMIBC and in all the intermediary/high- (int/high) risk patients. Vaccine-specific IgG titers were correlated to total urinary IgG levels, the latter being higher in the int/high-risk patients. In contrast, vaccine-specific IgA did not correlate to urinary IgA levels. Furthermore, vaccine-specific antibodies were transiently increased by intravesical BCG instillations. Altogether, our data show that a standard i.m. immunization can effectively induce antigen-specific antibodies in urine, which, upon selection of optimal vaccine targets, may provide protection against UTI. Vaccine-specific IgG titers were dependent on conditions affecting total urinary IgG levels, while production of vaccine-specific IgA in situ might independently contribute to protection against infections in the bladder. PATIENT SUMMARY: Towards the development of vaccines able to protect against urinary tract infections, we examined the potential of the intramuscular vaccination using a model antigen. We found two types of specific antibodies in the urine, which together may locally contribute to protection against infections, thus supporting the use of such a standard immunization route.

Effect and Analysis of Bacterial Lysates for the Treatment of Recurrent Urinary Tract Infections in Adults

Urinary tract infection (UTI) is a relevant public health problem, economically and socially affecting the lives of patients. The increase of antimicrobial bacterial resistance significantly hinders the treatment of UTIs, raising the need to search for alternative therapies. Bacterial lysates (BL) obtained from Escherichia coli and other pathogens have been used to treat different infectious diseases with promising results. This work aims to evaluate the effect and composition of an autologous BL for the treatment and control of recurrent UTIs in adults. The results show remission in 70% of the patients within the first three months after the administration of BL, while the infection is maintained under control for 6-12 months. The analysis by liquid chromatography-mass spectrometry (LC-MS) of the BL fractions recognized by the sera of patients shows the presence of cytosolic proteins, fimbriae, OMPs, and LPS. Our study demonstrates that the autologous BL contributed to the treatment and control of recurrent UTIs in adults, and its composition shows that different surface components of E. coli are potential immunogens that could be used to create a polyvalent protective vaccine.

Surface display of uropathogenic Escherichia coli FimH in Lactococcus lactis: In vitro characterization of recombinant bacteria and its protectivity in animal model

Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) are very common, leading to high patient morbidity and substantial medical costs. The development of non-antibiotic strategies such as food-grade lactic acid bacterium can be recognized as an attractive and safe alternative way against UTI. Here, we report the construction of Lactococcus lactis (L. lactis) strain genetically modified to produce FimH virulence factor of UPEC on the cell surface. We showed the FimH inserted into the pT1NX vector is actively synthesized on L. lactis. The L. lactis-pT1NX-FimH exhibited an auto-aggregation phenotype in liquid cultures and formed robust biofilm on abiotic surface compared to vector-only bacteria. Then, we developed protective biofilms with L. lactis strains and examined their inhibitory effect for exclusion of uropathogenic biofilm formation. In the natural protective biofilm assays, L. lactis-pT1NX-FimH resulted in significant reduction in the pathogen load when compared to the L. lactis-pT1NX. Evaluation of the colonization ability in the bladder showed that L. lactis expressing FimH survived better in the mice bladder than L. lactis harboring vector. Protection assay against UPEC infection was investigated using a UTI mouse model. L. lactis-pT1NX-FimH displayed high effectiveness in the protection of the bladder as compared to the control group after UPEC challenge. The results suggest that genetically engineered L. lactis-pT1NX-FimH can be used as a safe alternative way for control of biofilm formation in UPEC. Furthermore, the possibility of using L. lactis-pT1NX-FimH as a new promising strategy against UTIs caused by UPEC strains is proposed.

Rapid Bladder Interleukin-10 Synthesis in Response to Uropathogenic Escherichia coli Is Part of a Defense Strategy Triggered by the Major Bacterial Flagellar Filament FliC and Contingent on TLR5

Interleukin-10 is part of the immune response to urinary tract infection (UTI) due to E. coli, and it is important in the early control of infection in the bladder. Defining the mechanism of engagement of the immune system by the bacteria that enables the protective IL-10 response is critical to exploring how we might exploit this mechanism for new infection control strategies. In this study, we reveal part of the bacterial flagellar apparatus (FliC) is an important component that is sensed by and responsible for induction of IL-10 in the response to UPEC. We show this response occurs in a TLR5-dependent manner. Using infection prevention and control trials in mice infected with E. coli, this study also provides evidence that purified FliC might be of value in novel approaches for the treatment of UTI or in preventing infection by exploiting the FliC-triggered bladder transcriptome.

Urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) engages interleukin-10 (IL-10) as an early innate immune response to regulate inflammation and promote the control of bladder infection. However, the mechanism of engagement of innate immunity by UPEC that leads to elicitation of IL-10 in the bladder is unknown. Here, we identify the major UPEC flagellar filament, FliC, as a key bacterial component sensed by the bladder innate immune system responsible for the induction of IL-10 synthesis. IL-10 responses of human as well as mouse bladder epithelial cell-monocyte cocultures were triggered by flagella of three major UPEC representative strains, CFT073, UTI89, and EC958. FliC purified to homogeneity induced IL-10 in vitro and in vivo as well as other functionally related cytokines, including IL-6. The genome-wide innate immunological context of FliC-induced IL-10 in the bladder was defined using RNA sequencing that revealed a network of transcriptional and antibacterial defenses comprising 1,400 genes that were induced by FliC. Of the FliC-responsive bladder transcriptome, altered expression of il10 and 808 additional genes were dependent on Toll-like receptor 5 (TLR5), according to analysis of TLR5-deficient mice. Examination of the potential of FliC and associated innate immune signature in the bladder to boost host defense, based on prophylactic or therapeutic administration to mice, revealed significant benefits for the control of UPEC. We conclude that detection of FliC through TLR5 triggers rapid IL-10 synthesis in the bladder, and FliC represents a potential immune modulator that might offer benefit for the treatment or prevention of UPEC UTI.

IMPORTANCE Interleukin-10 is part of the immune response to urinary tract infection (UTI) due to E. coli, and it is important in the early control of infection in the bladder. Defining the mechanism of engagement of the immune system by the bacteria that enables the protective IL-10 response is critical to exploring how we might exploit this mechanism for new infection control strategies. In this study, we reveal part of the bacterial flagellar apparatus (FliC) is an important component that is sensed by and responsible for induction of IL-10 in the response to UPEC. We show this response occurs in a TLR5-dependent manner. Using infection prevention and control trials in mice infected with E. coli, this study also provides evidence that purified FliC might be of value in novel approaches for the treatment of UTI or in preventing infection by exploiting the FliC-triggered bladder transcriptome.