Enterococcal biofilm formation and virulence in an optimized murine model of foreign body-associated urinary tract infections

3D-Bioprinted Urinary Catheters Enable Sustained Probiotic Recovery Under Flow and Improve Bladder Colonization In Vivo

Catheter-associated urinary tract infections (CAUTIs) account for a large proportion of healthcare-associated infections. CAUTIs, caused by colonization of the catheter surface by uropathogens, are challenging to treat, especially when compounded by antibiotic resistance. One prophylactic strategy that could reduce pathogen colonization is bacterial interference, whereby the catheter surface is coated with non-pathogenic bacteria. Current challenges include identifying appropriate bacterial interference strains that maintain stable association with the catheter and are viable, but not pathogenic, in the urinary tract environment. This study evaluated the stability of probiotic Lactobacillus rhamnosus in 3D bioprints mimicking urinary catheter tubing under urine flow and assessed viability and safety in an in vivo mouse model. Bioprints underwent hydraulic flow testing in vitro with artificial urine media (AUM), followed by evaluation of catheter structure, L. rhamnosus recovery, and biofilm formation. Mice were inoculated with free L. rhamnosus bacteria or implanted with L. rhamnosus-containing bioprints to measure urinary tract colonization and assess effects on the bladder tissue. Bioprinted segments exhibited minimal mass change while maintaining an intact shape and demonstrated viable L. rhamnosus recovery throughout 7 days. L. rhamnosus formed biofilms on the bioprint surface that were not disrupted by urinary flow conditions. Encouragingly, L. rhamnosus viability was maintained in bioprints in a mouse urinary tract catheterization model. Bioprints released L. rhamnosus in vivo and did not cause histological inflammation beyond that generated by standard silicone catheters. In summary, L. rhamnosus bioprints exhibited key desirable characteristics, including maintenance of probiotic viability, probiotic growth on the catheter surface, and enhanced probiotic colonization of the bladder. This study supports the development of bioprinted probiotic catheters as a new strategy to prevent CAUTI.

Insights into ecology, pathogenesis, and biofilm formation of Enterococcus faecalis from functional genomics

SUMMARYEnterococcus faecalis is a significant resident of the gastrointestinal tract of most animals, including humans. Although generally non-pathogenic in healthy hosts, this microbe is adept at the exploitation of compromises in host immune functions, resulting in life-threatening opportunistic infections whose treatments are complicated by a high degree of intrinsic and acquired resistance to antimicrobial chemotherapy. Historically, progress in enterococcal research was limited by a lack of experimental models that replicate natural infection pathways and the relevance of in vitro studies to the natural biology of the organism. In this review, we summarize the history of enterococcal research during the 20th and early 21st centuries and describe more recent genetic and genomic tools and screens developed to address challenges in the field. We also describe how the results of recent studies reveal the importance of previously uncharacterized enterococcal genes, and we provide examples of interesting determinants that have emerged as important contributors to enterococcal biology. These factors may also serve as targets for future vaccines and chemotherapeutic agents to combat life-threatening hospital infections.

Metabolic interplay between Proteus mirabilis and Enterococcus faecalis facilitates polymicrobial biofilm formation and invasive disease

Biofilms play an important role in the development and pathogenesis of catheter-associated urinary tract infection (CAUTI). Proteus mirabilis and Enterococcus faecalis are common CAUTI pathogens that persistently co-colonize the catheterized urinary tract and form biofilms with increased biomass and antibiotic resistance. In this study, we uncover the metabolic interplay that drives biofilm enhancement and examine the contribution to CAUTI severity. Through compositional and proteomic biofilm analyses, we determined that the increase in biofilm biomass stems from an increase in the protein fraction of the polymicrobial biofilm. We further observed an enrichment in proteins associated with ornithine and arginine metabolism in polymicrobial biofilms compared with single-species biofilms. We show that arginine/ornithine antiport by E. faecalis promotes arginine biosynthesis and metabolism in P. mirabilis, ultimately driving the increase in polymicrobial biofilm protein content without affecting viability of either species. We further show that disrupting E. faecalis ornithine antiport alters the metabolic profile of polymicrobial biofilms and prevents enhancement, and this defect was complemented by supplementation with exogenous ornithine. In a murine model of CAUTI, ornithine antiport did not contribute to E. faecalis colonization but was required for the increased incidence of urinary stone formation and bacteremia that occurs during polymicrobial CAUTI with P. mirabilis. Thus, disrupting metabolic interplay between common co-colonizing species may represent a viable strategy for reducing risk of bacteremia.IMPORTANCEChronic infections often involve the formation of antibiotic-resistant biofilm communities that include multiple different microbes, which pose a challenge for effective treatment. In the catheterized urinary tract, potential pathogens persistently co-colonize for long periods of time and the interactions between them can lead to more severe disease outcomes. In this study, we identified the metabolite L-ornithine as a key mediator of disease-enhancing interactions between two common and challenging pathogens, Enterococcus faecalis and Proteus mirabilis. Disrupting ornithine-mediated interactions may therefore represent a strategy to prevent polymicrobial biofilm formation and decrease risk of severe disease.

Unraveling the role of UilS, a urea-induced acyl-homoserine lactonase that enhances Serratia marcescens fitness, interbacterial competition, and urinary tract infection

Serratia marcescens, a member of the Enterobacteriaceae family, is an opportunistic human pathogen and a frequent cause of urinary tract infections. Clinical isolates often exhibit resistance to multiple antibiotics, posing challenges for successful treatment. Understanding its pathogenic mechanisms is crucial for elucidating new potential targets to develop effective therapeutic interventions and manage S. marcescens infections. This work identifies urea-induced lactonase of Serratia (UilS), a lactonase encoded in the S. marcescens RM66262 strain isolated from a patient with a urinary tract infection. The study explores the bacterium's response to urea, a major component of urine, and its impact on uilS expression. We found that UilS degrades acyl-homoserine lactones (AHL) autoinducers traditionally associated with quorum sensing mechanisms. Surprisingly, UilS is able to degrade self and non-self AHL, exhibiting quorum-quenching activity toward Pseudomonas aeruginosa. We found that LuxR regulates uilS expression that is enhanced in the presence of AHL. In addition, urea-dependent induction of UilS expression is controlled by the transcriptional response regulator CpxR. UilS confers fitness advantage to S. marcescens, especially in the presence of urea, emphasizing the adaptive plasticity of strains to modulate gene expression based on environmental signals and population density. We also discovered a novel bacterial killing capacity of S. marcescens that involves UilS, indicating its importance in the interspecies interaction of Serratia. Finally, we found that a uilS mutant strain displays attenuated colonization in a mouse model of catheter-associated urinary tract infection. uilS is present in clinical but absent in environmental isolates, suggesting an evolutionary adaptation to host-specific selective pressures.

IMPORTANCE

This work reveals the acyl-homoserine lactonase urea-induced lactonase of Serratia as a novel virulence factor of Serratia marcescens, unraveling a potential target to develop antimicrobial strategies and shedding light on the complex regulatory network governing pathogenicity and adaptation to host environments.

The Extra Length of Stay, Costs, and Mortality Associated With Healthcare-Associated Infections: A Case-Control Study

Background and Aim

This study aims to compare the mortality rate, length of stay (LOS), and hospitalization cost in patients with and without healthcare-associated infections (HCAIs).

Methods

This prospective cohort study is conducted on 396 matched patients admitted to a tertiary teaching hospital with 800 beds in the southwest of Iran from July 2021 to January 2022. The cases were patients admitted during the study period who had, at minimum, one type of HCAI. For a comparison group, we considered all patients without HCAIs who hospitalized in the same ward and at the same time with the same age and gender in a ratio of one case to three controls. Descriptive analyses were done based on direct medical costs, LOS, and mortality rate in patients. The magnitude of the relationship between potential risk factors and HCAI was quantified using logistic regression.

Results

The most common HCAI and microorganisms were urinary tract infection (UTI) and Escherichia coli, respectively. The mean LOS for infected patients was 20.3 (±16) days, compared to 8.7 (±8.6) days for noninfected patients (p value ≤ 0.05). Lengths of stay (odds ratio [OR] = 1.09; 95% CI = 1.06-1.19; p value = 0.000), ICU lengths of stay (OR = 1.08; 95% CI = 1.02-1.15; p value = 0.003), presence of central Catheter (OR = 0.127; 95% CI = 0.51-0.319; p value = 0.000), and urinary catheter (OR = 0.225; 95% CI = 0.122-0.415; p value = 0.000), mechanical ventilation (OR = 0.136; 95% CI = 0.57-0.325; p value = 0.000), receipt of immunosuppressors (OR = 1.99; 95% CI = 11.12-3.56; p value = 0.01), were Significantly associated with HCAI. Patients with infections had a more costly hospital stay than noninfected patients (mean diff: $2037.46 ([SD]: 482.25$) (p value = 0.000). The highest cost component was the cost of medication expenditure (mean: $1612.66 ([SD]: $2542.27).

Conclusions

UTI was the most common HCAI in our study. An infection acquired during a hospital stay may be associated with higher hospitalization costs, prolonged hospitalization, and an increase in the rate of mortality. Longer lengths of stay, presence of central and urinary Catheters, receipt of immunosuppressors, use of mechanical ventilator were common risk factors for HCAI. This study reveals that the median reimbursement cost per hospitalization of patients with HCAIs was higher than patients without HCAIs. This highlights the necessity for implementation of HCAI prevention and control measures.

Conformational ensembles in Klebsiella pneumoniae FimH impact uropathogenesis

Klebsiella pneumoniae is an important pathogen causing difficult-to-treat urinary tract infections (UTIs). Over 1.5 million women per year suffer from recurrent UTI, reducing quality of life and causing substantial morbidity and mortality, especially in the hospital setting. Uropathogenic E. coli (UPEC) is the most prevalent cause of UTI. Like UPEC, K. pneumoniae relies on type 1 pili, tipped with the mannose-binding adhesin FimH, to cause cystitis. However, K. pneumoniae FimH is a poor binder of mannose, despite a mannose-binding pocket identical to UPEC FimH. FimH is composed of two domains that are in an equilibrium between tense (low-affinity) and relaxed (high-affinity) conformations. Substantial interdomain interactions in the tense conformation yield a low-affinity, deformed mannose-binding pocket, while domain-domain interactions are broken in the relaxed state, resulting in a high-affinity binding pocket. Using crystallography, we identified the structural basis by which domain-domain interactions direct the conformational equilibrium of K. pneumoniae FimH, which is strongly shifted toward the low-affinity tense state. Removal of the pilin domain restores mannose binding to the lectin domain, thus showing that poor mannose binding by K. pneumoniae FimH is not an inherent feature of the mannose-binding pocket. Phylogenetic analyses of K. pneumoniae genomes found that FimH sequences are highly conserved. However, we surveyed a collection of K. pneumoniae isolates from patients with long-term indwelling catheters and identified isolates that possessed relaxed higher-binding FimH variants, which increased K. pneumoniae fitness in bladder infection models, suggesting that long-term residence within the urinary tract may select for higher-binding FimH variants.

Advances in experimental bladder models: bridging the gap between in vitro and in vivo approaches for investigating urinary tract infections

Urinary tract infections (UTIs) pose a substantial burden on global healthcare systems. When unraveling the complex pathophysiology of UTIs, bladder models are used to understand complex and multifaceted interactions between different components within the system. This review aimed to bridge the gap between in vitro and in vivo experimental bladder models towards UTI research. We reviewed clinical, animal, and analytical studies and patents from 1959 to the end of 2023. Both in vivo and in vitro models offer unique benefits and drawbacks in understanding UTIs. In vitro models provide controlled environments for studying specific aspects of UTI biology and testing potential treatments, while in vivo models offer insights into how UTIs manifest and progress within living organisms. Thus, both types of models are leading to the development of more effective diagnostic tools and therapeutic interventions against UTIs. Moreover, advanced methodologies involving three-dimensional bladder organoids have also been used to study bladder biology, model bladder-related disorders, and explore new treatments for bladder cancers, UTIs, and urinary incontinence. Narrowing the distance between fundamental scientific research and practical medical applications, these pioneering models hold the key to unlocking new avenues for the development of personalized diagnostics, precision medicine, and ultimately, the alleviation of UTI-related morbidity worldwide.

Macrophage fate: to kill or not to kill?

Macrophages are dynamic innate immune cells that either reside in tissue, serving as sentinels, or recruited as monocytes from bone marrow into inflamed and infected tissue. In response to cues in the tissue microenvironment (TME), macrophages polarize on a continuum toward M1 or M2 with diverse roles in progression and resolution of disease. M1-like macrophages exhibit proinflammatory functions with antimicrobial and anti-tumorigenic activities, while M2-like macrophages have anti-inflammatory functions that generally resolve inflammatory responses and orchestrate a tissue healing process. Given these opposite phenotypes, proper spatiotemporal coordination of macrophage polarization in response to cues within the TME is critical to effectively resolve infectious disease and regulate wound healing. However, if this spatiotemporal coordination becomes disrupted due to persistent infection or dysregulated coagulation, macrophages' inappropriate response to these cues will result in the development of diseases with clinically unfavorable outcomes. Since plasticity and heterogeneity are hallmarks of macrophages, they are attractive targets for therapies to reprogram toward specific phenotypes that could resolve disease and favor clinical prognosis. In this review, we discuss how basic science studies have elucidated macrophage polarization mechanisms in TMEs during infections and inflammation, particularly coagulation. Therefore, understanding the dynamics of macrophage polarization within TMEs in diseases is important in further development of targeted therapies.

Function and contribution of two putative Enterococcus faecalis glycosaminoglycan degrading enzymes to bacteremia and catheter-associated urinary tract infection

Enterococcus faecalis is a common cause of healthcare-acquired bloodstream infections and catheter-associated urinary tract infections (CAUTIs) in both adults and children. Treatment of E. faecalis infection is frequently complicated by multi-drug resistance. Based on protein homology, E. faecalis encodes two putative hyaluronidases, EF3023 (HylA) and EF0818 (HylB). In other Gram-positive pathogens, hyaluronidases have been shown to contribute to tissue damage and immune evasion, but the function in E. faecalis has yet to be explored. Here, we show that both hylA and hylB contribute to E. faecalis pathogenesis. In a CAUTI model, ΔhylA exhibited defects in bladder colonization and dissemination to the bloodstream, and ΔhylB exhibited a defect in kidney colonization. Furthermore, a ΔhylAΔhylB double mutant exhibited a severe colonization defect in a model of bacteremia while the single mutants colonized to a similar level as the wild-type strain, suggesting potential functional redundancy within the bloodstream. We next examined enzymatic activity, and demonstrate that HylB is capable of digesting both hyaluronic acid (HA) and chondroitin sulfate in vitro, while HylA exhibits only a very modest activity against heparin. Importantly, HA degradation by HylB provided a modest increase in cell density during the stationary phase and also contributed to dampening of lipopolysaccharide-mediated NF-κB activation. Overall, these data demonstrate that glycosaminoglycan degradation is important for E. faecalis pathogenesis in the urinary tract and during bloodstream infection.

Metabolic interplay between Proteus mirabilis and Enterococcus faecalis facilitates polymicrobial biofilm formation and invasive disease

Polymicrobial biofilms play an important role in the development and pathogenesis of CAUTI. Proteus mirabilis and Enterococcus faecalis are common CAUTI pathogens that persistently co-colonize the catheterized urinary tract and form biofilms with increased biomass and antibiotic resistance. In this study, we uncover the metabolic interplay that drives biofilm enhancement and examine the contribution to CAUTI severity. Through compositional and proteomic biofilm analyses, we determined that the increase in biofilm biomass stems from an increase in the protein fraction of the polymicrobial biofilm matrix. We further observed an enrichment in proteins associated with ornithine and arginine metabolism in polymicrobial biofilms compared to single-species biofilms. We show that L-ornithine secretion by E. faecalis promotes arginine biosynthesis in P. mirabilis, and that disruption of this metabolic interplay abrogates the biofilm enhancement we see in vitro and leads to significant decreases in infection severity and dissemination in a murine CAUTI model.

The role of the universal sugar transport system components PtsI (EI) and PtsH (HPr) in Enterococcus faecium

Vancomycin-resistant enterococci (VRE) pose a serious threat to public health because of their limited treatment options. Therefore, there is an increasing need to identify novel targets to develop new drugs. Here, we examined the roles of the universal PTS components, PtsI and PtsH, in Enterococcus faecium to determine their roles in carbon metabolism, biofilm formation, stress response, and the ability to compete in the gastrointestinal tract. Clean deletion of ptsHI resulted in a significant reduction in the ability to import and metabolize simple sugars, attenuated growth rate, reduced biofilm formation, and decreased competitive fitness both in vitro and in vivo. However, no significant difference in stress survival was observed when compared with the wild type. These results suggest that targeting universal or specific PTS may provide a novel treatment strategy by reducing the fitness of E. faecium.

Function and contribution of two putative Enterococcus faecalis glycosaminoglycan degrading enzymes to bacteremia and catheter-associated urinary tract infection

Enterococcus faecalis is a common cause of healthcare acquired bloodstream infections and catheter associated urinary tract infections (CAUTI) in both adults and children. Treatment of E. faecalis infection is frequently complicated by multi-drug resistance. Based on protein homology, E. faecalis encodes two putative hyaluronidases, EF3023 (HylA) and EF0818 (HylB). In other Gram-positive pathogens, hyaluronidases have been shown to contribute to tissue damage and immune evasion, but function in E. faecalis has yet to be explored. Here, we show that both hylA and hylB contribute to E. faecalis pathogenesis. In a CAUTI model, Δ hylA exhibited defects in bladder colonization and dissemination to the bloodstream, and Δ hylB exhibited a defect in kidney colonization. Furthermore, a Δ hylA Δ hylB double mutant exhibited a severe colonization defect in a model of bacteremia while the single mutants colonized to a similar level as the wild-type strain, suggesting potential functional redundancy within the bloodstream. We next examined enzymatic activity, and demonstrate that HylB is capable of digesting both HA and CS in vitro while HylA exhibits only a very modest activity against heparin. Importantly, HA degradation by HylB provided a modest increase in cell density during stationary phase and also contributed to dampening of LPS-mediated NF-Bκ activation. Overall, these data demonstrate that glycosaminoglycan degradation is important for E. faecalis pathogenesis in the urinary tract and during bloodstream infection.

Bioinspired Nanozymes as Nanodecoys for Urinary Tract Infection Treatment

Urinary tract infections (UTIs), common bacterial infections in communities and medical facilities, are mainly mediated by FimH. The glycan sites of the uromodulin protein play a crucial role in protecting against UTIs by interacting with FimH. A bioinspired approach using glycan-FimH interactions may effectively reduce bacteria through an antiadhesive mechanism, thereby curbing bacterial resistance. However, typical antiadhesive therapy alone fails to address the excessive reactive oxygen species and inflammatory response during UTIs. To bridge this gap, antioxidant nanozymes with antiadhesive ability were developed as nanodecoys to counter bacteria and inflammation. Specifically, ultrasmall dextran-coated ceria (DEC) was engineered to address UTIs, with dextran blocking FimH adhesion and ceria exhibiting anti-inflammatory properties. DECs, metabolizable by the kidneys, reduced bacterial content in the urinary tract, mitigating inflammation and tissue damage. In murine models, DECs successfully treated acute UTIs, repeated infections, and catheter-related UTIs. This dual approach not only highlights the potential of nanozymes for UTIs but also suggests applicability to other FimH-induced infections in the lungs and bowels, marking a significant advancement in nanozyme-based clinical approaches.

Tackling catheter-associated urinary tract infections with next-generation antimicrobial technologies

Urinary catheters and other medical devices associated with the urinary tract such as stents are major contributors to nosocomial urinary tract infections (UTIs) as they provide an access path for pathogens to enter the bladder. Considering that catheter-associated urinary tract infections (CAUTIs) account for approximately 75% of UTIs and that UTIs represent the most common type of healthcare-associated infections, novel anti-infective device technologies are urgently required. The rapid rise of antimicrobial resistance in the context of CAUTIs further highlights the importance of such preventative strategies. In this review, the risk factors for pathogen colonization in the urinary tract are dissected, taking into account the nature and mechanistics of this unique environment. Moreover, the most promising next-generation preventative strategies are critically assessed, focusing in particular on anti-infective surface coatings. Finally, emerging approaches in this field and their likely clinical impact are examined.

Uncovering Surface Penetration by Enterococci From Urinary Tract Infection Patients

IMPORTANCE

The relationship between Enterococcus faecalis vaginal colonization and urinary tract infections (UTIs) remains uncertain.

OBJECTIVE

We aimed to evaluate the surface invasion capability of E faecalis isolates from patients with and without UTIs as a potential readout of pathogenicity.

STUDY DESIGN

Participants were females from urogynecology clinics, comprising symptomatic UTI and asymptomatic non-UTI patients, categorized by the presence or absence of E faecalis-positive cultures identified via standard urine culture techniques. Vaginal and urine samples from patients were plated on enterococci selective medium, and E faecalis isolates detected in both cohorts were species specific identified using 16S rRNA sequencing. Clinical isolates were inoculated on semisolid media, and both external colonies and underneath colony prints formed by agar-penetrating enterococci were imaged. External growth and invasiveness were quantified by determining colony-forming units of the noninvading and agar-penetrating cells and compared with the E faecalis OG1RF.

RESULTS

We selected E faecalis isolates from urine and vaginal samples of 4 patients with and 4 patients without UTIs. Assays demonstrated that most isolates formed similarly sized external colonies with comparable colony-forming unit. Surface invasion differed across patients and isolation sites compared with OG1RF. The vaginal isolate from UTI patient 1, who had the most recurrences, exhibited significantly greater agar-invading capacity compared with OG1RF.

CONCLUSIONS

Our pilot study indicates that ex vivo invasion assays may unveil virulence traits in E faecalis from UTI patients. Enhanced enterococcal surface penetration could increase urogenital invasion risk. Further research is needed to correlate penetration with disease severity in a larger patient group.

Purine and carbohydrate availability drive Enterococcus faecalis fitness during wound and urinary tract infections

IMPORTANCE

Although E. faecalis is a common wound pathogen, its pathogenic mechanisms during wound infection are unexplored. Here, combining a mouse wound infection model with in vivo transposon and RNA sequencing approaches, we identified the E. faecalis purine biosynthetic pathway and galactose/mannose MptABCD phosphotransferase system as essential for E. faecalis acute replication and persistence during wound infection, respectively. The essentiality of purine biosynthesis and the MptABCD PTS is driven by the consumption of purine metabolites by E. faecalis during acute replication and changing carbohydrate availability during the course of wound infection. Overall, our findings reveal the importance of the wound microenvironment in E. faecalis wound pathogenesis and how these metabolic pathways can be targeted to better control wound infections.

Genetic and functional enrichments associated with Enterococcus faecalis isolated from the urinary tract

IMPORTANCE

Urinary tract infection (UTI) is a global health issue that imposes a substantial burden on healthcare systems. Women are disproportionately affected by UTI, with >60% of women experiencing at least one UTI in their lifetime. UTIs can recur, particularly in postmenopausal women, leading to diminished quality of life and potentially life-threatening complications. Understanding how pathogens colonize and survive in the urinary tract is necessary to identify new therapeutic targets that are urgently needed due to rising rates of antimicrobial resistance. How Enterococcus faecalis, a bacterium commonly associated with UTI, adapts to the urinary tract remains understudied. Here, we generated a collection of high-quality closed genome assemblies of clinical urinary E. faecalis isolated from the urine of postmenopausal women that we used alongside detailed clinical metadata to perform a robust comparative genomic investigation of genetic factors that may be involved in E. faecalis survival in the urinary tract.

Differential Contribution of Hydrogen Metabolism to Proteus mirabilis Fitness during Single-Species and Polymicrobial Catheterized Urinary Tract Infection

Proteus mirabilis is a common uropathogen and a leading cause of catheter-associated urinary tract infections (CAUTIs), which are often polymicrobial. Through a genome-wide screen, we previously identified two [NiFe] hydrogenases as candidate fitness factors for P. mirabilis CAUTI: a Hyb-type Group 1c H2-uptake hydrogenase and a Hyf-type Group 4a H2-producing hydrogenase. In this study, we disrupted one gene of each system (hyfE and hybC) and also generated a double mutant to examine the contribution of flexible H2 metabolism to P. mirabilis growth and fitness in vitro and during experimental CAUTI. Since P. mirabilis is typically present as part of a polymicrobial community in the urinary tract, we also examined the impact of two common co-colonization partners, Providencia stuartii and Enterococcus faecalis, on the expression and contribution of each hydrogenase to fitness. Our data demonstrate that neither system alone is critical for P. mirabilis growth in vitro or fitness during experimental CAUTI. However, perturbation of flexible H2 metabolism in the ∆hybC∆hyfE double mutant decreased P. mirabilis fitness in vitro and during infection. The Hyf system alone contributed to the generation of proton motive force and swarming motility, but only during anaerobic conditions. Unexpectedly, both systems contributed to benzyl viologen reduction in TYET medium, and disruption of either system increased expression of the other. We further demonstrate that polymicrobial interactions with P. stuartii and E. faecalis alter the expression of Hyb and Hyf in vitro as well as the contribution of each system to P. mirabilis fitness during CAUTI.

Preclinical Evaluation of Nitroxide-Functionalised Ciprofloxacin as a Novel Antibiofilm Drug Hybrid for Urinary Tract Infections

Urinary tract infections (UTIs) are the second most common bacterial infection with high recurrence rates and can involve biofilm formation on patient catheters. Biofilms are inherently tolerant to antimicrobials, making them difficult to eradicate. Many antibiofilm agents alone do not have bactericidal activity; therefore, linking them to antibiotics is a promising antibiofilm strategy. However, many of these hybrid agents have not been tested in relevant preclinical settings, limiting their potential for clinical translation. Here, we evaluate a ciprofloxacin di-nitroxide hybrid (CDN11), previously reported to have antibiofilm activity against uropathogenic Escherichia coli (UPEC) strain UTI89 in vitro, as a potential UTI therapeutic using multiple preclinical models that reflect various aspects of UTI pathogenesis. We report improved in vitro activity over the parent drug ciprofloxacin against mature UTI89 biofilms formed inside polyethylene catheters. In bladder cell monolayers infected with UTI89, treatment with CDN11 afforded significant reduction in bacterial titers, including intracellular UPEC. Infected mouse bladders containing biofilm-like intracellular reservoirs of UPEC UTI89 showed decreased bacterial loads after ex vivo bladder treatment with CDN11. Activity for CDN11 was reported across different models of UTI, showcasing nitroxide-antibiotic hybridization as a promising antibiofilm approach. The pipeline we described here could be readily used in testing other new therapeutic compounds, fast-tracking the development of novel antibiofilm therapeutics.

Alteration of the oral and gut microbiota in patients with Kawasaki disease

Background

Kawasaki disease (KD) is a multi-systemic vasculitis that primarily affects children and has an unknown cause. Although an increasing number of studies linking the gut microbiota with KD, the unchallengeable etiology of KD is not available.

Methods

Here, we obtained fecal and oral samples from KD patients and healthy controls, and then we use high-throughput sequencing to examine the diversity and composition of microbiota.

Results

Results showed that both in the gut and oral microbiota, the diversity of KD patients was significantly lower than that of the healthy controls. In the gut microbiota, a higher abundance of Enterococcus (40.12% vs less than 0.1%), Bifidobacterium (20.71% vs 3.06%), Escherichia-Shigella (17.56% vs 0.61%), Streptococcus (5.97% vs 0.11%) and Blautia (4.69% vs 0.1%) was observed in the KD patients, and enrichment of Enterococcus in the patients was observed. In terms of oral microbiota, the prevalence of Streptococcus (21.99% vs 0.1%), Rothia (3.02% vs 0.1%), and Escherichia-Shigella (0.68% vs 0.0%) were significantly higher in the KD patients, with the enrichment of Streptococcus and Escherichia-Shigella. Additionally, significant differences in microbial community function between KD patients and healthy controls in the fecal samples were also observed, which will affect the colonization and reproduction of gut microbiota.

Conclusions

These results suggested that the dysbiosis of gut and oral microbiota are both related to KD pathogenesis, of which, the prevalence of Enterococcus in the gut and higher abundance of Streptococcus and Escherichia-Shigella in the oral cavity will be a potential biomarker of the KD. Overall, this study not only confirms that the disturbance of gut microbiota is a causative trigger of KD but also provides new insight into the oral microbiota involved in KD pathogenesis.

Top-Down Genomic Surveillance Approach To Investigate the Genomic Epidemiology and Antibiotic Resistance Patterns of Enterococcus faecium Detected in Cancer Patients in Arkansas

Control of hospital-associated Enterococcus faecium infection is a strenuous task due to the difficulty of identifying transmission routes and the persistence of this nosocomial pathogen despite the implementation of infection control measures that have been successful with other important nosocomial pathogens. This study provides a comprehensive analysis of over 100 E. faecium isolates collected from 66 cancer patients at the University of Arkansas for Medical Sciences (UAMS) between June 2018 and May 2019. In the top-down approach used in this study, we employed, in addition to the 106 E. faecium UAMS isolates, a filtered set of 2,167 E. faecium strains from the GenBank database to assess the current population structure of E. faecium species and, consequently, to identify the lineages associated with our clinical isolates. We then evaluated the antibiotic resistance and virulence profiles of hospital-associated strains from the species pool, focusing on antibiotics of last resort, to establish an updated classification of high-risk and multidrug-resistant nosocomial clones. Further investigation of the clinical isolates collected from UAMS patients using whole-genome sequencing analytical methodologies (core genome multilocus sequence typing [cgMLST], core single nucleotide polymorphism [coreSNP] analysis, and phylogenomics), with the addition of patient epidemiological data, revealed a polyclonal outbreak of three sequence types occurring simultaneously in different patient wards. The integration of genomic and epidemiological data collected from the patients increased our understanding of the relationships and transmission dynamics of the E. faecium isolates. Our study provides new insights into genomic surveillance of E. faecium to assist in monitoring and further limiting the spread of multidrug-resistant E. faecium. IMPORTANCE Enterococcus faecium is a member of the gastrointestinal microbiota. Although its virulence is low in healthy, immunocompetent individuals, E. faecium has become the third leading cause of health care-associated infections in the United States. This study provides a comprehensive analysis of over 100 E. faecium isolates collected from cancer patients at the University of Arkansas for Medical Sciences (UAMS). We employed a top-down analytical approach (from population genomics to molecular biology) to classify our clinical isolates into their genetic lineages and thoroughly evaluate their antibiotic resistance and virulence profiles. The addition of patient epidemiological data to the whole-genome sequencing analytical methodologies performed in the study allowed us to increase our understanding of the relationships and transmission dynamics of the E. faecium isolates. This study provides new insights into genomic surveillance of E. faecium to help monitor and further limit the spread of multidrug-resistant E. faecium.

Functional and genetic adaptations contributing to Enterococcus faecalis persistence in the female urinary tract

Enterococcus faecalis is the leading Gram-positive bacterial species implicated in urinary tract infection (UTI). An opportunistic pathogen, E. faecalis is a commensal of the human gastrointestinal tract (GIT) and its presence in the GIT is a predisposing factor for UTI. The mechanisms by which E. faecalis colonizes and survives in the urinary tract (UT) are poorly understood, especially in uncomplicated or recurrent UTI. The UT is distinct from the GIT and is characterized by a sparse nutrient landscape and unique environmental stressors. In this study, we isolated and sequenced a collection of 37 clinical E. faecalis strains from the urine of primarily postmenopausal women. We generated 33 closed genome assemblies and four highly contiguous draft assemblies and conducted a comparative genomics to identify genetic features enriched in urinary E. faecalis with respect to E. faecalis isolated from the human GIT and blood. Phylogenetic analysis revealed high diversity among urinary strains and a closer relatedness between urine and gut isolates than blood isolates. Plasmid replicon (rep) typing further underscored possible UT-GIT interconnection identifying nine shared rep types between urine and gut E. faecalis . Both genotypic and phenotypic analysis of antimicrobial resistance among urinary E. faecalis revealed infrequent resistance to front-line UTI antibiotics nitrofurantoin and fluoroquinolones and no vancomycin resistance. Finally, we identified 19 candidate genes enriched among urinary strains that may play a role in adaptation to the UT. These genes are involved in the core processes of sugar transport, cobalamin import, glucose metabolism, and post-transcriptional regulation of gene expression.

IMPORTANCE

Urinary tract infection (UTI) is a global health issue that imposes substantial burden on healthcare systems. Women are disproportionately affected by UTI with >60% of women experiencing at least one UTI in their lifetime. UTIs can recur, particularly in postmenopausal women, leading to diminished quality of life and potentially life-threatening complications. Understanding how pathogens colonize and survive in the urinary tract is necessary to identify new therapeutic targets that are urgently needed due to rising rates of antimicrobial resistance. How Enterococcus faecalis , a bacterium commonly associated with UTI, adapts to the urinary tract remains understudied. Here, we generated a collection of high-quality closed genome assemblies of clinical urinary E. faecalis isolated from the urine of postmenopausal women that we used alongside detailed clinical metadata to perform a robust comparative genomic investigation of genetic factors that may mediate urinary E. faecalis adaptation to the female urinary tract.

The catheterized bladder environment promotes Efg1- and Als1-dependent Candida albicans infection

Catheter-associated urinary tract infections (CAUTIs) account for 40% of hospital-acquired infections (HAIs). As 20 to 50% of hospitalized patients receive catheters, CAUTIs are one of the most common HAIs, resulting in increased morbidity, mortality, and health care costs. Candida albicans is the second most common CAUTI uropathogen, yet relative to its bacterial counterparts, little is known about how fungal CAUTIs are established. Here, we show that the catheterized bladder environment induces Efg1- and fibrinogen (Fg)-dependent biofilm formation that results in CAUTI. In addition, we identify the adhesin Als1 as the critical fungal factor for C. albicans Fg-urine biofilm formation. Furthermore, we show that in the catheterized bladder, a dynamic and open system, both filamentation and attachment are required, but each by themselves are not sufficient for infection. Our study unveils the mechanisms required for fungal CAUTI establishment, which may aid in the development of future therapies to prevent these infections.

Catheterization of mice triggers resurgent urinary tract infection seeded by a bladder reservoir of Acinetobacter baumannii

The antibiotic-resistant bacterium Acinetobacter baumannii is a leading cause of hospital-associated infections. Despite surveillance and infection control efforts, new A. baumannii strains are regularly isolated from health care facilities worldwide. In a mouse model of urinary tract infection, we found that mice infected with A. baumannii displayed high bacterial burdens in urine for several weeks. Two months after the resolution of A. baumannii infection, inserting a catheter into the bladder of mice with resolved infection led to the resurgence of a same-strain urinary tract infection in ~53% of the mice within 24 hours. We identified intracellular A. baumannii bacteria in the bladder epithelial cells of mice with resolved infection, which we propose could act as a host reservoir that was activated upon insertion of a catheter, leading to a resurgent secondary infection.

In Vivo Role of Two-Component Regulatory Systems in Models of Urinary Tract Infections

Two-component signaling systems (TCSs) are finely regulated mechanisms by which bacteria adapt to environmental conditions by modifying the expression of target genes. In bacterial pathogenesis, TCSs play important roles in modulating adhesion to mucosal surfaces, resistance to antibiotics, and metabolic adaptation. In the context of urinary tract infections (UTI), one of the most common types infections causing significant health problems worldwide, uropathogens use TCSs for adaptation, survival, and establishment of pathogenicity. For example, uropathogens can exploit TCSs to survive inside bladder epithelial cells, sense osmolar variations in urine, promote their ascension along the urinary tract or even produce lytic enzymes resulting in exfoliation of the urothelium. Despite the usefulness of studying the function of TCSs in in vitro experimental models, it is of primary necessity to study bacterial gene regulation also in the context of host niches, each displaying its own biological, chemical, and physical features. In light of this, the aim of this review is to provide a concise description of several bacterial TCSs, whose activity has been described in mouse models of UTI.

Virulence factors of uropathogens and their role in host pathogen interactions

Gram-positive and Gram-negative bacterial pathogens are commonly found in Urinary Tract Infection (UTI), particularly infected in females like pregnant women, elder people, sexually active, or individuals prone to other risk factors for UTI. In this article, we review the expression of virulence surface proteins and their interaction with host cells for the most frequently isolated uropathogens: Escherichia coli, Enterococcus faecalis, Proteus mirabilis, Klebsiella pneumoniae, and Staphylococcus saprophyticus. In addition to the host cell interaction, surface protein regulation was also discussed in this article. The surface protein regulation serves as a key tool in differentiating the pathogen isotypes. Furthermore, it might provide insights on novel diagnostic methods to detect uropathogen that are otherwise easily overlooked due to limited culture-based assays. In essence, this review shall provide an in-depth understanding on secretion of virulence factors of various uropathogens and their role in host-pathogen interaction, this knowledge might be useful in the development of therapeutics against uropathogens.

Comparative metabolite profiling of four polyphenol rich Morus leaves extracts in relation to their antibiofilm activity against Enterococcus faecalis

Enterococci are a common cause of urinary tract infections. The severity of enterococcal infections is associated with their ability to form biofilms. Morus leaves are known as a natural antibacterial, however, their antibiofilm activity against Enterococcus remains unveiled. This study aimed to evaluate the ability of four polyphenol-rich Morus leaves extracts (Morus nigra, M. rubra, M. macroura, and M. alba) to inhibit biofilm formed by enterococcal clinical isolates in relation to their metabolic profiling. Results revealed that 48% of the isolates formed strong biofilm, 28% formed moderate biofilm, 20% formed weak biofilm, and only 4% did not form a biofilm. The strong biofilm-forming isolates were E. faecalis, and hence were chosen for this study. The antibiofilm activity of the four polyphenol-rich Morus leaves extracts revealed that the M. nigra extract exhibited the highest percentage of biofilm inhibition followed by M. rubra then M. macroura and the least inhibition was detected in M. alba, and these results were in accordance with the phenolic and flavonoid contents of each extract. UPLC-ESI-MS/MS identified 61 polyphenolic compounds in the four extracts. Further, multivariate analysis confirmed clear segregation of M. nigra from the other species suggesting disparity in its metabolome, with accumulation of flavonoids, anthocyanidins, phenolic acids and coumarin derivatives. Quercetin and kaempferol glycosides were found to be positively and significantly correlated to the antibiofilm activity. In conclusion, M. nigra ethanolic extracts showed the highest phenolic content and antibiofilm activity and they could be developed as a complementary treatment for the development of antimicrobial agents.

Ring-fused 2-pyridones effective against multidrug-resistant Gram-positive pathogens and synergistic with standard-of-care antibiotics

The alarming rise of multidrug-resistant Gram-positive bacteria has precipitated a healthcare crisis, necessitating the development of new antimicrobial therapies. Here we describe a new class of antibiotics based on a ring-fused 2-pyridone backbone, which are active against vancomycin-resistant enterococci (VRE), a serious threat as classified by the Centers for Disease Control and Prevention, and other multidrug-resistant Gram-positive bacteria. Ring-fused 2-pyridone antibiotics have bacteriostatic activity against actively dividing exponential phase enterococcal cells and bactericidal activity against nondividing stationary phase enterococcal cells. The molecular mechanism of drug-induced killing of stationary phase cells mimics aspects of fratricide observed in enterococcal biofilms, where both are mediated by the Atn autolysin and the GelE protease. In addition, combinations of sublethal concentrations of ring-fused 2-pyridones and standard-of-care antibiotics, such as vancomycin, were found to synergize to kill clinical strains of VRE. Furthermore, a broad range of antibiotic resistant Gram-positive pathogens, including those responsible for the increasing incidence of antibiotic resistant healthcare-associated infections, are susceptible to this new class of 2-pyridone antibiotics. Given the broad antibacterial activities of ring-fused 2-pyridone compounds against Gram-positive (GmP) bacteria we term these compounds GmPcides, which hold promise in combating the rising tide of antibiotic resistant Gram-positive pathogens.

Preferential catabolism of l- vs d-serine by Proteus mirabilis contributes to pathogenesis and catheter-associated urinary tract infection

Proteus mirabilis is a common cause of urinary tract infection, especially in catheterized individuals. Amino acids are the predominant nutrient for bacteria during growth in urine, and our prior studies identified several amino acid import and catabolism genes as fitness factors for P. mirabilis catheter-associated urinary tract infection (CAUTI), particularly those for d- and l-serine. In this study, we sought to determine the hierarchy of amino acid utilization by P. mirabilis and to examine the relative importance of d- vs l-serine catabolism for critical steps in CAUTI development and progression. Herein, we show that P. mirabilis preferentially catabolizes l-serine during growth in human urine, followed by d-serine, threonine, tyrosine, glutamine, tryptophan, and phenylalanine. Independently disrupting catabolism of either d- or l-serine has minimal impact on in vitro phenotypes while completely disrupting both pathways decreases motility, biofilm formation, and fitness due to perturbation of membrane potential and cell wall biosynthesis. In a mouse model of CAUTI, loss of either serine catabolism system decreased fitness, but disrupting l-serine catabolism caused a greater fitness defect than disrupting d-serine catabolism. We, therefore, conclude that the hierarchical utilization of amino acids may be a critical component of P. mirabilis colonization and pathogenesis within the urinary tract.

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.

Synergistic Antibacterial Activity of Green Synthesized Silver Nanomaterials with Colistin Antibiotic against Multidrug-Resistant Bacterial Pathogens

The high frequency of nosocomial bacterial infections caused by multidrug-resistant pathogens contributes to significant morbidity and mortality worldwide. As a result, finding effective antibacterial agents is of critical importance. Hence, the aim of the present study was to greenly synthesize silver nanoparticles (AgNPs) utilizing Salvia officinalis aqueous leaf extract. The biogenic AgNPs were characterized utilizing different physicochemical techniques such as energy-dispersive X-ray spectroscopy (EDX), ultraviolet-visible spectrophotometry (UV-Vis), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) analysis. Additionally, the synergistic antimicrobial effectiveness of the biosynthesized AgNPs with colistin antibiotic against multidrug-resistant bacterial strains was evaluated utilizing the standard disk diffusion assay. The bioformulated AgNPs revealed significant physicochemical features, such as a small particle size of 17.615 ± 1.24 nm and net zeta potential value of −16.2 mV. The elemental mapping of AgNPs revealed that silver was the main element, recording a relative mass percent of 83.16%, followed by carbon (9.51%), oxygen (5.80%), silicon (0.87%), and chloride (0.67%). The disc diffusion assay revealed that AgNPs showed antibacterial potency against different tested bacterial pathogens, recording the highest efficiency against the Escherichia coli strain with an inhibitory zone diameter of 37.86 ± 0.21 mm at an AgNPs concentration of 100 µg/disk. In addition, the antibacterial activity of AgNPs was significantly higher than that of colistin (p ≤ 0.05) against the multidrug resistant bacterial strain namely, Acinetobacter baumannii. The biosynthesized AgNPs revealed synergistic antibacterial activity with colistin antibiotic, demonstrating the highest synergistic percent against the A. baumannii strain (85.57%) followed by Enterobacter cloacae (53.63%), E. coli (35.76%), Klebsiella pneumoniae (35.19%), Salmonella typhimurium (33.06%), and Pseudomonas aeruginosa (13.75%). In conclusion, the biogenic AgNPs revealed unique physicochemical characteristics and significant antibacterial activities against different multidrug-resistant bacterial pathogens. Consequently, the potent synergistic effect of the AgNPs–colistin combination highlights the potential of utilizing this combination for fabrication of highly effective antibacterial coatings in intensive care units for successful control of the spread of nosocomial bacterial infections.

Characterization and anti-biofilm activity of bacteriophages against urinary tract Enterococcus faecalis isolates

Strong biofilm-forming Enterococcus feacalis urinary tract pathogens (n = 35) were used to determine the lytic spectrum of six bacteriophages isolated from sewage samples. Only 17 Enterococcus feacalis isolates gave lytic zones with the tested bacteriophages from which five isolates were susceptible to all of them. The isolated enterococcal phages are characterized by wide range of thermal (30–90 °C) and pH (3–10) stability. They belong to order Caudovirales, from which four bacteriophages (EPA, EPB, EPD, EPF) belong to family Myoviridae and two (EPC, EPE) belong to family Siphoviridae. In addition, they have promising antibiofilm activity against the tested strong-forming biofilm E. faecalis isolates. The enterococcal phages reduced the formed and preformed biofilms to a range of 38.02–45.7% and 71.0–80.0%, respectively, as compared to the control. The same promising activities were obtained on studying the anti-adherent effect of the tested bacteriophages on the adherence of bacterial cells to the surface of urinary catheter segments. They reduced the number of adherent cells to a range of 30.8–43.8% and eradicated the pre-adherent cells to a range of 48.2–71.1%, as compared to the control. Overall, the obtained promising antibiofilm activity makes these phages good candidates for application in preventing and treating biofilm associated Enterococcus faecalis infections.

Gender differences in the microbial spectrum and antibiotic sensitivity of uropathogens isolated from patients with urinary stones

Purpose

The characteristics and resistance patterns of urine bacteriology urolithiasis patients between male and female have not been extensively studied. This study aims to investigate the gender differences in microbial spectrum and antibiotic susceptibility of uropathogens isolated from urolithiasis patients and provide insights for appropriate antimicrobial therapies.

Materials and Methods

We retrospectively collected clinical microbiology data from urine culture in urolithiasis patients between March 2014 and December 2018 in Xiangya Hospital. Then the patients were divided into male and female groups. The microbial spectrum and frequency of susceptibility to antibiotics were compared.

Results

A total of 359 uropathogen isolates were collected from 335 patients, including 144 males (43.0%) and 191 females (57.0%). E. coli dominated in both groups, indicating higher frequency in females (53.2%) than in males (26.6%, p < 0.001), followed by E. faecalis, with higher frequency in males (15.6%) than in females (2.9%, p < 0.001). Major Gram‐negative (E. coli and K. pneumoniae) bacteria showed high sensitivity to cefoperazone/sulbactam, cefotetan, piperacillin/ tazobactam, and amikacin. In contrast, the resistance level was high to penicillin, tetracycline, and vancomycin in both groups. Gram‐positive (E. faecalis and E. faecium) isolates demonstrated high sensitivity to gentamicin and vancomycin in both groups. Furthermore, uropathogens isolated from female urolithiasis patients were more susceptible to antimicrobials than males.

Conclusions

Uropathogen microbial spectrum in female urolithiasis patients is different from males. High susceptibility antibiotics should be used empirically according to gender to avoid multidrug‐resistant bacteria increase.

Activity of CcpA-Regulated GH18 Family Glycosyl Hydrolases That Contributes to Nutrient Acquisition and Fitness in Enterococcus faecalis

The ability of Enterococcus faecalis to colonize host anatomical sites is dependent on its adaptive response to host conditions. Three glycosyl hydrolase gene clusters, each belonging to glycosyl hydrolase family 18 (GH18) (ef0114, ef0361, and ef2863), in E. faecalis were previously found to be upregulated under glucose-limiting conditions. The GH18 catalytic domain is present in proteins that are classified as either chitinases or β-1,4 endo-β-N-acetylglucosaminidases (ENGases) based on their β-1,4 endo-N-acetyl-β-d-glucosaminidase activity, and ENGase activity is commonly associated with cleaving N-linked glycoprotein, an abundant glycan structure on host epithelial surfaces. Here, we show that all three hydrolases are negatively regulated by the transcriptional regulator carbon catabolite protein A (CcpA). Additionally, we demonstrate that a constitutively active CcpA variant represses the expression of CcpA-regulated genes irrespective of glucose availability. Previous studies showed that the GH18 catalytic domains of EndoE (EF0114) and EfEndo18A (EF2863) were capable of deglycosylating RNase B, a model high-mannose-type glycoprotein. However, it remained uncertain which glycosidase is primarily responsible for the deglycosylation of high-mannose-type glycoproteins. In this study, we show by mutation analysis as well as a dose-dependent analysis of recombinant protein expression that EfEndo18A is primarily responsible for deglycosylating high-mannose glycoproteins and that the glycans removed by EfEndo18A support growth under nutrient-limiting conditions in vitro. In contrast, IgG is representative of a complex-type glycoprotein, and we demonstrate that the GH18 domain of EndoE is primarily responsible for the removal of this glycan decoration. Finally, our data highlight the combined contribution of glycosidases to the virulence of E. faecalis in vivo.

Comparison of urine fibrinogen and interleukin-6 concentrations between healthy dogs and dogs with risk factors for enterococcal bacteriuria

OBJECTIVE

To compare urine concentrations of fibrinogen (uFIB) and interleukin-6 (uIL-6) between dogs with risk factors for enterococcal bacteriuria and healthy dogs.

SAMPLE

Banked urine samples with negative aerobic culture results from 8 dogs with urolithiasis, 9 dogs with anatomic abnormalities of the lower portion of the urinary tract (LUT), 10 dogs with LUT neoplasia, and 21 healthy control dogs.

PROCEDURES

Urine creatinine concentration (uCrea) was determined by an automated biochemical analyzer, and uFIB and uIL-6 were determined by dog-specific ELISAs. The uFIB:uCrea and uIL-6:uCrea ratios were calculated for each sample to normalize intersample differences in urine concentration and were compared among the 4 experimental groups.

RESULTS

Median uFIB:uCrea ratios for dogs with urolithiasis (0.72; interquartile [25th to 75 percentile] range [IQR], 0.46 to 3.48) and LUT neoplasia (6.16; IQR, 3.89 to 12.75), but not for dogs with LUT anatomic abnormalities (0.48; IQR, 0.27 to 0.69), were significantly greater than that for control dogs (0.17; IQR, 0.07 to 0.39). Median uIL-6: uCrea ratios for dogs with urolithiasis (0.48; IQR, 0.18 to 1.61), LUT anatomic abnormalities (0.25; IQR, 0.17 to 0.33), and LUT neoplasia (0.25; IQR, 0.12 to 1.01) were significantly greater than that for control dogs (0.08; IQR, 0.06 to 0.11).

CONCLUSIONS AND CLINICAL RELEVANCE

The uFIB and uIL-6 in dogs with risk factors for enterococcal bacteriuria were generally greater than corresponding values in control dogs. Further investigation is necessary to determine the role of fibrinogen in enterococcal colonization of the urinary tract of dogs.

A mouse model displays host and bacterial strain differences in Aerococcus urinae urinary tract infection

In recent years, the clinical significance of Aerococcus urinae has been increasingly recognized. A. urinae has been implicated in cases of urinary tract infection (UTI; acute cystitis and pyelonephritis) in both male and female patients, ranging from children to older adults. Aerococcus urinae can also be invasive, causing urosepsis, endocarditis, and musculoskeletal infections. Mechanisms of pathogenesis in A. urinae infections are poorly understood, largely due to the lack of an animal model system. In response to this gap, we developed a model of A. urinae urinary tract infection in mice. We compared A. urinae UTI in female C3H/HeN and C57BL/6 mice and compared four clinical isolates of A. urinae isolated from patients with UTI, urgency urinary incontinence, and overactive bladder. Our data demonstrate that host genetic background modulates A. urinae UTI. Female C57BL/6 female mice rapidly cleared the infection. Female C3H/HeN mice, which have inherent vesicoureteral reflux that flushes urine from the bladder up into the kidneys, were susceptible to prolonged bacteriuria. This result is consistent with the fact that A. urinae infections most frequently occur in patients with underlying urinary tract abnormalities or disorders that make them susceptible to bacterial infection. Unlike uropathogens such as E. coli, which cause infection and inflammation both of the bladder and kidneys in C3H/HeN mice, A. urinae displayed tropism for the kidney, persisting in kidney tissue even after clearance of bacteria from the bladder. Aerococcus urinae strains from different genetic clades displayed varying propensities to cause persistent kidney infection. Aerococcus urinae infected kidneys displayed histological inflammation, neutrophil recruitment and increased pro-inflammatory cytokines. These results set the stage for future research that interrogates host-pathogen interactions between A. urinae and the urinary tract.

Summary:Aerococcus urinae clinical isolates are genetically diverse and display differential capacity to cause UTI in a mouse model. Infection was rapidly cleared from the bladder, but persisted and caused inflammation in the kidney.

Catalase Activity is Critical for Proteus mirabilis Biofilm Development, EPS Composition, and Dissemination During Catheter-Associated Urinary Tract Infection

Proteus mirabilis is a leading uropathogen of catheter-associated urinary tract infections (CAUTIs), which are among the most common healthcare-associated infections worldwide. A key factor that contributes to P. mirabilis pathogenesis and persistence during CAUTI is the formation of catheter biofilms, which provide increased resistance to antibiotic treatment and host defense mechanisms. Another factor that is important for bacterial persistence during CAUTI is the ability to resist reactive oxygen species (ROS), such as through the action of the catalase enzyme. Potent catalase activity is one of the defining biochemical characteristics of P. mirabilis, and the single catalase gene (katA) encoded in strain HI4320 was recently identified as a candidate fitness factor for UTI, CAUTI, and bacteremia. Here we show that disruption of katA results in increased ROS levels, increased sensitivity to peroxide, and decreased biofilm biomass. The biomass defect was due to a decrease in extracellular polymeric substances (EPS) production by the ΔkatA mutant, and specifically due to reduced carbohydrate content. Importantly, the biofilm defect resulted in decreased antibiotic resistance in vitro and a colonization defect during experimental CAUTI. The ΔkatA mutant also exhibited decreased fitness in a bacteremia model, supporting a dual role for catalase in P. mirabilis biofilm development and immune evasion.

In Vitro Reduction of Interleukin-8 Response to Enterococcus faecalis by Escherichia coli Strains Isolated from the Same Polymicrobial Urines

Urinary tract infections are often polymicrobial and are mainly due to uropathogenic Escherichia coli (UPEC). We previously demonstrated a link among clinical fluoroquinolone susceptible E. coli reducing in vitro urothelial interleukin-8 (CXCL8) induced by E. coli K-12, polymicrobial cystitis, and pyuria absence. Here, we evaluated whether fifteen clinical fluoroquinolone susceptible UPEC were able to reduce CXCL8 induced by Enterococcus faecalis that had been isolated from the same mixed urines, other than CXCL8 induced by E. coli K-12. We also evaluated the connection between fluoroquinolone susceptibility and pathogenicity by evaluating the immune modulation of isogenic gyrA, a mutant UPEC resistant to ciprofloxacin. Using the 5637 bladder epithelial cell line, we observed that lower CXCL8 induced the most UPEC isolates than K-12 and the corresponding E. faecalis. During coinfections of UPEC/K-12 and UPEC/E. faecalis, we observed lower CXCL8 than during infections caused by K-12 and E. faecalis alone. UPEC strains showed host–pathogen and pathogen–pathogen interaction, which in part explained their persistence in the human urinary tract and coinfections, respectively. Mutant UPEC showed lower modulating activity with respect to the wildtypes, confirming the connection between acquired fluoroquinolone resistance and the decrease of innate microbial properties.

Mimicking biofilm formation and development: Recent progress in in vitro and in vivo biofilm models

Biofilm formation in living organisms is associated to tissue and implant infections, and it has also been linked to the contribution of antibiotic resistance. Thus, understanding biofilm development and being able to mimic such processes is vital for the successful development of antibiofilm treatments and therapies. Several decades of research have contributed to building the foundation for developing in vitro and in vivo biofilm models. However, no such thing as an "all fit" in vitro or in vivo biofilm models is currently available. In this review, in addition to presenting an updated overview of biofilm formation, we critically revise recent approaches for the improvement of in vitro and in vivo biofilm models.

Influence of the Alternative Sigma Factor RpoN on Global Gene Expression and Carbon Catabolism in Enterococcus faecalis V583

The alternative sigma factor σ⁵⁴ has been shown to regulate the expression of a wide array of virulence-associated genes, as well as central metabolism, in bacterial pathogens. In Gram-positive organisms, the σ⁵⁴ is commonly associated with carbon metabolism. In this study, we show that the Enterococcus faecalis alternative sigma factor σ⁵⁴ (RpoN) and its cognate enhancer binding protein MptR are essential for mannose utilization and are primary contributors to glucose uptake through the Mpt phosphotransferase system. To gain further insight into how RpoN contributes to global transcriptional changes, we performed microarray transcriptional analysis of strain V583 and an isogenic rpoN mutant grown in a chemically defined medium with glucose as the sole carbon source. Transcripts of 340 genes were differentially affected in the rpoN mutant; the predicted functions of these genes mainly related to nutrient acquisition. These differentially expressed genes included those with predicted catabolite-responsive element (cre) sites, consistent with loss of repression by the major carbon catabolite repressor CcpA. To determine if the inability to efficiently metabolize glucose/mannose affected infection outcome, we utilized two distinct infection models. We found that the rpoN mutant is significantly attenuated in both rabbit endocarditis and murine catheter-associated urinary tract infection (CAUTI). Here, we examined a ccpA mutant in the CAUTI model and showed that the absence of carbon catabolite control also significantly attenuates bacterial tissue burden in this model. Our data highlight the contribution of central carbon metabolism to growth of E. faecalis at various sites of infection.

Marine Microbial-Derived Antibiotics and Biosurfactants as Potential New Agents against Catheter-Associated Urinary Tract Infections

Catheter-associated urinary tract infections (CAUTIs) are among the leading nosocomial infections in the world and have led to the extensive study of various strategies to prevent infection. However, despite an abundance of anti-infection materials having been studied over the last forty-five years, only a few types have come into clinical use, providing an insignificant reduction in CAUTIs. In recent decades, marine resources have emerged as an unexplored area of opportunity offering huge potential in discovering novel bioactive materials to combat human diseases. Some of these materials, such as antimicrobial compounds and biosurfactants synthesized by marine microorganisms, exhibit potent antimicrobial, antiadhesive and antibiofilm activity against a broad spectrum of uropathogens (including multidrug-resistant pathogens) that could be potentially used in urinary catheters to eradicate CAUTIs. This paper summarizes information on the most relevant materials that have been obtained from marine-derived microorganisms over the last decade and discusses their potential as new agents against CAUTIs, providing a prospective proposal for researchers.

Altered gut microbiota correlated with systemic inflammation in children with Kawasaki disease

Kawasaki disease (KD) is a multi-systemic vasculitis of unknown etiology that occurs mainly in children, and the disturbance of gut microbiota is generally believed to cause a hyperimmune reaction triggering KD. The aim of the study was to investigate the alterations in the fecal microbiota and assess its relationship with systemic inflammation. Totally 30 KD children were enrolled and followed up for 6 months, with another group of 30 age- and sex-matched healthy children as controls. Phylotype profiles of fecal microbial communities were analyzed using 16S rRNA gene sequencing. Serum inflammatory markers were detected by flow cytometer. We showed that KD children exhibited a significant reduction in fecal microbial diversity in the acute phase compared with the healthy controls. Enterococcus, Acinetobacter, Helicobacter, Lactococcus, Staphylococcus and Butyricimonas in acute KD children were significantly higher than the healthy children. Levels of systemic inflammation biomarkers, including IL-2, IL-4, IL-6, IL-10, TNF-α, and INF-γ, were significantly elevated in the acute KD children. Altered microbiota genera Enterococcus and Helicobacter abundances were shown to be correlated positively with IL-6, which were never previously reported in KD. This study suggested that gut microbiota alteration is closely associated with systemic inflammation, which provides a new perspective on the etiology and pathogenesis of KD.

Targeting Biofilms Therapy: Current Research Strategies and Development Hurdles

Biofilms are aggregate of microorganisms in which cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS) and adhere to each other and/or to a surface. The development of biofilm affords pathogens significantly increased tolerances to antibiotics and antimicrobials. Up to 80% of human bacterial infections are biofilm-associated. Dispersal of biofilms can turn microbial cells into their more vulnerable planktonic phenotype and improve the therapeutic effect of antimicrobials. In this review, we focus on multiple therapeutic strategies that are currently being developed to target important structural and functional characteristics and drug resistance mechanisms of biofilms. We thoroughly discuss the current biofilm targeting strategies from four major aspects—targeting EPS, dispersal molecules, targeting quorum sensing, and targeting dormant cells. We explain each aspect with examples and discuss the main hurdles in the development of biofilm dispersal agents in order to provide a rationale for multi-targeted therapy strategies that target the complicated biofilms. Biofilm dispersal is a promising research direction to treat biofilm-associated infections in the future, and more in vivo experiments should be performed to ensure the efficacy of these therapeutic agents before being used in clinic.

Involvement of Chromosomally Encoded Homologs of the RRNPP Protein Family in Enterococcus faecalis Biofilm Formation and Urinary Tract Infection Pathogenesis

Enterococcus faecalis is an opportunistic pathogen capable of causing infections, including endocarditis and urinary tract infections (UTI). One of the well-characterized quorum-sensing pathways in E. faecalis involves coordination of the conjugal transfer of pheromone-responsive plasmids by PrgX, a member of the RRNPP protein family. Members of this protein family in various Firmicutes have also been shown to contribute to numerous cellular processes, including sporulation, competence, conjugation, nutrient sensing, biofilm formation, and virulence. As PrgX is a plasmid-encoded RRNPP family member, we surveyed the genome of the multidrug-resistant strain V583 for additional RRNPP homologs using computational searches and refined those identified hits for predicted structural similarities to known RRNPP family members. This led us to investigate the contribution of the chromosomally encoded RRNPP homologs to biofilm processes and pathogenesis in a catheter-associated urinary tract infection (CAUTI) model. In this study, we identified five such homologs and report that 3 of the 5 homologs, EF0073, EF1599, and EF1316, affect biofilm formation as well as outcomes in the CAUTI model.IMPORTANCE Enterococcus faecalis causes health care-associated infections and displays resistance to a variety of broad-spectrum antibiotics by acquisition of resistance traits as well as the ability to form biofilms. Even though a growing number of factors related to biofilm formation have been identified, mechanisms that contribute to biofilm formation are still largely unknown. Members of the RRNPP protein family regulate a diverse set of biological reactions in low-G+C Gram-positive bacteria (Firmicutes). Here, we identify three predicted structural homologs of the RRNPP family, EF0073, EF1599, and EF1316, which affect biofilm formation and CAUTI pathogenesis.

Photothermal Antibacterial and Antibiofilm Activity of Black Phosphorus/Gold Nanocomposites against Pathogenic Bacteria

Black phosphorus (BP) as a layered two-dimensional (2D) semiconductor material with a tunable band gap has attracted growing attention for promising applications in diverse fields including biotechnology owing to its excellent physical and chemical properties. In this study, BP crystals were synthesized using a chemical vapor transport method and exfoliated into BP nanosheets in deoxygenated water or hexane. Next, monodisperse Au nanoparticles that were synthesized using a surfactant-assisted chemical reduction method were assembled on exfoliated BP nanosheets hexane to yield BP/Au nanocomposites. The photothermal antibacterial and antibiofilm activities of BP nanosheets and BP/Au nanocomposites were investigated against Enterococcus faecalis, a pathogenic biofilm-forming bacterium, by studying the photothermal effect and bacterial growth curve and using colony counting and live/dead fluorescence staining methods under near-infrared (NIR) light irradiation. Thanks to the higher photothermal conversion efficiency of BP/Au nanocomposites than that of bare BP nanosheets under NIR light irradiation, they destructed the bacterial cell membrane more efficiently than bare BP with the biofilm inhibition rate of 58%. It should be noted that this is the first study on the antibacterial and antibiofilm activity of BP/Au nanocomposites via a photothermal process under NIR light irradiation. This work shows the potential of BP/Au nanocomposites in fighting against pathogenic bacteria and paves the way for the exploration of antibacterial platforms based on the biocompatible 2D semiconductor BP.

Transposon Insertion Site Sequencing of Providencia stuartii: Essential Genes, Fitness Factors for Catheter-Associated Urinary Tract Infection, and the Impact of Polymicrobial Infection on Fitness Requirements

Providencia stuartii is a common cause of polymicrobial catheter-associated urinary tract infection (CAUTI), and yet literature describing the molecular mechanisms of its pathogenesis is limited. To identify factors important for colonization during single-species infection and during polymicrobial infection with a common cocolonizer, Proteus mirabilis, we created a saturating library of ∼50,000 transposon mutants and conducted transposon insertion site sequencing (Tn-Seq) in a murine model of CAUTI. P. stuartii strain BE2467 carries 4,398 genes, 521 of which were identified as essential for growth in laboratory medium and therefore could not be assessed for contribution to infection. Using an input/output fold change cutoff value of 20 and P values of <0.05, 340 genes were identified as important for establishing single-species infection only and 63 genes as uniquely important for polymicrobial infection with P. mirabilis, and 168 genes contributed to both single-species and coinfection. Seven mutants were constructed for experimental validation of the primary screen that corresponded to flagella (fliC mutant), twin arginine translocation (tatC), an ATP-dependent protease (clpP), d-alanine-d-alanine ligase (ddlA), type 3 secretion (yscI and sopB), and type VI secretion (impJ). Infection-specific phenotypes validated 6/7 (86%) mutants during direct cochallenge with wild-type P. stuartii and 3/5 (60%) mutants during coinfection with P. mirabilis, for a combined validation rate of 9/12 (75%). Tn-Seq therefore successfully identified genes that contribute to fitness of P. stuartii within the urinary tract, determined the impact of coinfection on fitness requirements, and added to the identification of a collection of genes that may contribute to fitness of multiple urinary tract pathogens.IMPORTANCE Providencia stuartii is a common cause of polymicrobial catheter-associated urinary tract infections (CAUTIs), particularly during long-term catheterization. However, little is known regarding the pathogenesis of this organism. Using transposon insertion site sequencing (Tn-Seq), we performed a global assessment of P. stuartii fitness factors for CAUTI while simultaneously determining how coinfection with another pathogen alters fitness requirements. This approach provides four important contributions to the field: (i) the first global estimation of P. stuartii genes essential for growth in laboratory medium, (ii) identification of novel fitness factors for P. stuartii colonization of the catheterized urinary tract, (iii) identification of core fitness factors for both single-species and polymicrobial CAUTI, and (iv) assessment of conservation of fitness factors between common uropathogens. Genomewide assessment of the fitness requirements for common uropathogens during single-species and polymicrobial CAUTI thus elucidates complex interactions that contribute to disease severity and will uncover conserved targets for therapeutic intervention.

Ynt is the primary nickel import system used by Proteus mirabilis and specifically contributes to fitness by supplying nickel for urease activity

Proteus mirabilis is a Gram-negative uropathogen and frequent cause of catheter-associated urinary tract infection (CAUTI). One important virulence factor is its urease enzyme, which requires nickel to be catalytically active. It is, therefore, hypothesized that nickel import is critical for P. mirabilis urease activity and pathogenesis during infection. P. mirabilis strain HI4320 encodes two putative nickel import systems, designated Nik and Ynt. By disrupting the substrate-binding proteins from each import system (nikA and yntA), we show that Ynt is the primary nickel importer, while Nik only compensates for loss of Ynt at high nickel concentrations. We further demonstrate that these are the only binding proteins capable of importing nickel for incorporation into the urease enzyme. Loss of either nickel-binding protein results in a significant fitness defect in a murine model of CAUTI, but YntA is more crucial as the yntA mutant was significantly outcompeted by the nikA mutant. Furthermore, despite the importance of nickel transport for hydrogenase activity, the sole contribution of yntA and nikA to virulence is due to their role in urease activity, as neither mutant exhibited a fitness defect when disrupted in a urease-negative background.

Overcoming the challenge of establishing biofilms in vivo: a roadmap for Enterococci

Enterococcus faecalis forms single and mixed-species biofilms on both tissue and medical devices in the host, often under exposure to fluid flow, giving rise to infections that are recalcitrant to treatment. The factors that drive enterococcal biofilm formation in the host, however, remain unclear. Recent reports in other pathogens show how surface sensing by bacteria can trigger the transition from planktonic to sessile lifestyle. Fluid flow can enhance initial adhesion, but also influence quorum sensing. Biofilm-specific factors, as well as biofilm size and extracellular polymeric substances, can compromise opsonization and phagocytosis. Bacterial interspecies synergy can create favorable conditions in the host for biofilm formation. Through these concepts, we define the knowledge gaps in understanding host-associated E. faecalis biofilm formation and propose a roadmap for future investigations.

A Rare Opportunist, Morganella morganii, Decreases Severity of Polymicrobial Catheter-Associated Urinary Tract Infection

Catheter-associated urinary tract infections (CAUTIs) are common hospital-acquired infections and frequently polymicrobial, which complicates effective treatment. However, few studies experimentally address the consequences of polymicrobial interactions within the urinary tract, and the clinical significance of polymicrobial bacteriuria is not fully understood. Proteus mirabilis is one of the most common causes of monomicrobial and polymicrobial CAUTI and frequently cocolonizes with Enterococcus faecalis, Escherichia coli, Providencia stuartii, and Morganella morganiiP. mirabilis infections are particularly challenging due to its potent urease enzyme, which facilitates formation of struvite crystals, catheter encrustation, blockage, and formation of urinary stones. We previously determined that interactions between P. mirabilis and other uropathogens can enhance P. mirabilis urease activity, resulting in greater disease severity during experimental polymicrobial infection. Our present work reveals that M. morganii acts on P. mirabilis in a contact-independent manner to decrease urease activity. Furthermore, M. morganii actively prevents urease enhancement by E. faecalis, P. stuartii, and E. coli Importantly, these interactions translate to modulation of disease severity during experimental CAUTI, predominantly through a urease-dependent mechanism. Thus, products secreted by multiple bacterial species in the milieu of the catheterized urinary tract can directly impact prognosis.