Biology subjects

De Nisco, N. J.

Publications and source records attributed to De Nisco, N. J..

15 recordsLinked to original sources

bioRxiv2026

Gain of Function Cytolysin Variant Expressed by Clinically Isolated Urinary Enterococcus faecalis

Cytolysin is a toxin-bacteriocin commonly encoded by Enterococcus faecalis that can target erythrocytes, neutrophils, and macrophages as well as other Gram-positive bacteria. Cytolysin can lyse human, horse, rabbit, and mouse erythrocytes, but not sheep erythrocytes (SEs). It is hypothesized that SEs are resistant to cytolysin because they lack phosphatidylcholine (PC) in their membranes, while susceptible erythrocytes have PC-rich membranes, suggesting PC as a cytolysin binding target. Here, we isolated a urinary E. faecalis strain C33 that can efficiently lyse SEs and found that this activity was conserved among several E. faecalis clinical isolates. We demonstrated that although C33 cytolysin was necessary for SE lysis, it was not sufficient, suggesting a secondary factor enhances cytolysin activity against SEs. Through liposome assays we found that while PC was required for the activity of DS16 cytolysin, PC was dispensable for C33 cytolysin activity. To assess the biological significance of C33 cytolysin in the bladder microenvironment, we assessed C33 cytolysin activity against bladder epithelial cells and the urinary microbiota. We found that C33 cytolysin was more cytotoxic to human bladder epithelial cells than the canonical DS16 cytolysin. We also found greater inhibition of co-isolated urinary microbiota species Streptococcus parasanguinis, Enterococcus raffinosus, Staphylococcus capitis, and Corynebacterium coyleae by C33 cytolysin. Interestingly, E. faecalis C33 also inhibited the protective urogenital taxa Lactobacillus crispatus and Bifidobacterium longum. Together, these results reveal a new PC-independent cytolysin activity among clinical E. faecalis isolates that may support survival and competition in the urinary microenvironment.

microbiology↗

bioRxiv2026

Polystyrene Microplastics Accelerate Antibiotic Resistance Evolution and Exacerbate Pathogenicity in Acinetobacter Baumannii

Microplastics are pervasive environmental contaminants and are increasingly detected in contexts relevant to human health, yet their effects on antimicrobial resistance, host-pathogen interactions, and infection outcomes remain poorly understood. Here, we show that exposure to polystyrene microplastics alters both antibiotic resistance evolution and pathogenic behavior in Acinetobacter baumannii, a leading cause of multidrug-resistant hospital-acquired infections. Using experimental evolution under antibiotic selection, we demonstrate that microplastic exposure accelerates resistance emergence across multiple antibiotic classes. Although microplastic exposure did not uniformly enhance biofilm formation, it modestly impaired macrophage-mediated bacterial clearance, suggesting broader effects on bacterial adaptation and host interaction. In vivo, microplastic-associated infection resulted in more severe disease, characterized by increased lung tissue damage and reduced survival in a murine model of A. baumannii pneumonia. Together, these findings identify microplastics as ecological modifiers of bacterial adaptation, linking widespread plastic pollution to enhanced antimicrobial resistance and worsened infectious disease outcomes.

microbiology↗

bioRxiv2026

Fatty acid auxotrophy as driver of Lactobacillus symbiosis in the female urinary tract

The female urinary microbiome (FUM) has emerged a promising therapeutic target for recurrent urinary traction infection (rUTI). The FUM is dominated by a phylogenetically coherent group of Lactobacillus species whose metabolic relationship with the host remains poorly understood. Here, we demonstrate that fatty acid (FA) auxotrophy is a universal, conserved trait of FUM Lactobacillus species, mechanistically underpinned by complete loss or inactivation of the fab operon encoding Type II fatty acid synthesis (FASII). Stable isotope tracing with [U-{superscript 1}3C] glucose confirms that L. crispatus and L. gasseri incorporate no glycolysis-derived carbon into cellular lipids, while generalist, non-FUM Lactobacillaceae species retain de novo FA biosynthesis. Gene synteny analysis across the Lactobacillaceae family reveals that fab operon loss is strongly associated with host-adapted lifestyles. Despite phenotypic FA auxotrophy among L. crispatus strains, a complete syntenic fab operon was identified in 31.9% of L. crispatus genomes. However, genomic inspection revealed a pervasive, inactivating frameshift mutation in fabH, the gene encoding the rate-limiting initiation condensing enzyme, in fab+ L. crispatus genomes highlighting two distinct evolutionary pathways of FA auxotrophy among this critically important FUM species. FA specificity assays establish L. crispatus and L. gasseri have an obligate requirement for monounsaturated FAs of C14-C20 chain length and that these species do not structurally modify supplemented FAs. Metabolic tracing further demonstrates that FUM lactobacilli directly scavenge and incorporate FAs from human bladder epithelial lipids, producing a bacterial membrane composition that mirrors the host. These findings establish FA auxotrophy as a defining adaptation to the female urogenital niche, with direct implications for development of microbiome-based therapies for rUTI.

microbiology↗

bioRxiv2026

Strain level variation in Proteus mirabilis chondroitin sulfate degradation kinetics and regulation by urea

To establish infection, uropathogens must overcome several host defenses including the glycosaminoglycan (GAG) layer coating the apical surface of the bladder urothelium. GAGs are thought to protect against urinary tract infection (UTI) by serving as scaffolding sites for commensals, providing barrier function and preventing uropathogen adherence. However, the ability of uropathogens to degrade and utilize GAGs and the contribution of these activities toward UTI progression is largely unknown. We previously discovered that the uropathogen Proteus mirabilis, a common cause of catheter-associated UTI (CAUTI), degrades the GAG chondroitin sulfate (CS). In this study we sought to define the kinetics and regulation of CS degradation by diverse P. mirabilis strains clinically isolated from both recurrent UTI and CAUTI patients. We found variation in CS degradation kinetics between P. mirabilis strains and media types. However, CS degradation depended on conserved putative chondroitin sulfate ABC endo- and exolyases in all strains. Furthermore, we found that CS degradation in Pm123 was repressed by urea and that this repression was dependent on P. mirabilis urease activity. Complementation of the Pm123 endolyase into urea-insensitive HI4320 resulted in a urea-sensitive CS degradation phenotype suggesting functional differences between the Pm123 and HI4320 endolyases. Sequence alignment and structural modeling analysis identified two unique point mutations within the Pm123 endolyase that may contribute to urea sensitivity. Finally, unlike urea-insensitive P. mirabilis strains, Pm123 demonstrated attenuated swarming and loss of chondroitin endolyase activity had no effect on Pm123 virulence in a mouse CAUTI model. Our results suggest that the kinetics and regulation of CS degradation differ between P. mirabilis strains and in urea-sensitive strains, thus reduces the contribution of CS degradation to urovirulence during murine CAUTI. ImportanceThis work demonstrates that the ability to degrade a common component of bladder mucosal surfaces, chondroitin sulfate, is a phenotype that is shared by multiple strains of the common catheter-associated UTI (CAUTI) pathogen P. mirabilis. We find that this activity is dependent on encoded chondroitin ABC endo- and exolyases, first described in Proteus vulgaris. Additionally, we discovered that for P. mirabilis strain Pm123, degradation of CS is negatively regulated by the presence of urea, a major component of urine. The repression of CS degradation by urea is dependent on the activity of the P. mirabilis urease enzyme, which breaks down urea producing ammonia which raises pH. We found expression of the Pm123 CS endolyase was sufficient to confer a urea-sensitive CS-degradation phenotype and identified two unique mutations within the Pm123 enzyme that may contribute to urea sensitivity. Finally, we find that while CS-degradation plays a role in progression and severity of murine CAUTI model in urea-insensitive P. mirabilis, there was not significant difference in CAUTI outcomes between the urea-sensitive Pm123 wild-type and chondroitinase knockout strains. This study represents a major step forward in understanding the diversity of CS degradation activity and regulation among clinical strains of the critically important CAUTI pathogen P. mirabilis as well as its contribution to urovirulence.

microbiology↗

bioRxiv2026

Chondroitin sulfate degradation bolsters Proteus mirabilis growth and colonization of the catheterized urinary tract

Glycosaminoglycans (GAGs) are negatively charged polysaccharides composed of repeating disaccharide units and are essential components of the extracellular matrix throughout numerous tissues. The bladder urothelium has a thick protective GAG layer that primarily consists of chondroitin sulfate (CS), heparan sulfate (HS), and hyaluronic acid (HA), and urinary tract pathogens must either degrade or otherwise circumvent this layer to infect the urothelium. In this study, we investigated GAG degradation by Proteus mirabilis, a common and persistent colonizer of the catheterized urinary tract. Almost all P. mirabilis urinary tract isolates harbor a putative chondroitin endolyase (PMI2127), exolyase (PMI2128), and sulfatase (PMI2124). By generating mutant and complemented strains of these genes, we determined that P. mirabilis strain HI4320 degrades multiple forms of CS under numerous culture conditions, including during growth in human urine, and can use CS degradation products as a carbon source. Sulfatase and endolyase activity were required for efficient degradation of all CS types, while the exolyase only contributed to using CS-B or CS-C as carbon source. Interestingly, only endolyase activity contributed to colonization in a murine model of CAUTI, although the colonization defect was even more pronounced when the endolyase and exolyase were both disrupted. The colonization defect was specific to the CAUTI model, likely due to the impact of catheterization on the GAG landscape of the bladder. Limiting CS degradation by P. mirabilis may therefore represent a strategy for reducing risk of ascending infection in catheterized patients. ImportanceGlycosaminoglycans (GAGs) are a family of negatively charged heteropolysaccharides that are ubiquitously expressed throughout the body, forming a significant component of the extracellular matrix and a luminal GAG layer in the bladder. This GAG layer functions as a physical barrier for the bladder surface, protecting it from bacterial infection. Disruption of this barrier through physical forces, such as catheter insertion, or enzymatic degradation by bacteria may contribute to infection outcomes. In this study, we defined the contribution of three putative chondroitin sulfate degrading enzymes (PMI2124, PMI2127, PMI2128) to the pathogenesis of a common pathogen in the catharized urinary tract, Proteus mirabilis. We found that P. mirabilis can utilize chondroitin sulfate as a carbon source, and that chondroitin sulfate degradation contributes to infection in a model of catheterized urinary tract infection. This work contributes to a growing understanding of how uropathogens subvert host defenses and acquire nutrients within the bladder.

microbiology↗

bioRxiv2024

Urinary biochemical ecology reveals microbiome-metabolite interactions and metabolic markers of recurrent urinary tract infection

Recurrent urinary tract infections (rUTIs) are a major clinical challenge and their increasing prevalence underscores the need to define host-microbiome interactions underlying susceptibility. How the urinary microbiota engages with the biochemical environment of the urogenital tract is yet to be fully defined. Here, we leverage paired metagenomic and quantitative metabolomic data to establish a microbe-metabolite association network of the female urinary microbiome and define metabolic signatures of rUTI. We observe unique metabolic networks of uropathogens and uroprotective species, highlighting potential metabolite-driven ecological shifts influencing rUTI susceptibility. We find distinct metabolites are associated with urinary microbiome diversity and identify a lipid signature of active rUTI that accurately distinguishes cases from controls. Finally, we identify deoxycholic acid as a prognostic indicator for UTI recurrence. Together these findings provide insight into microbiome-metabolite interactions within the female urinary tract and highlight new biomarkers for the development of new diagnostic tools to improve patient outcomes.

microbiology↗

bioRxiv2024

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, {Delta}hylA exhibited defects in bladder colonization and dissemination to the bloodstream, and {Delta}hylB exhibited a defect in kidney colonization. Furthermore, a {Delta}hylA{Delta}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-B{kappa} activation. Overall, these data demonstrate that glycosaminoglycan degradation is important for E. faecalis pathogenesis in the urinary tract and during bloodstream infection.

microbiology↗

bioRxiv2023

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. IMPORTANCEUrinary 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.

microbiology↗

bioRxiv2023

Aging-associated augmentation of gut microbiome virulence capability drives sepsis severity.

Prior research has focused on host factors as mediators of exaggerated sepsis-associated morbidity and mortality in older adults. This focus on the host, however, has failed to identify therapies that improve sepsis outcomes in the elderly. We hypothesized that the increased susceptibility of the aging population to sepsis is not only a function of the host, but also reflects longevity-associated changes in the virulence of gut pathobionts. We utilized two complementary models of gut microbiota-induced experimental sepsis to establish the aged gut microbiome as a key pathophysiologic driver of heightened disease severity. Further murine and human investigations into these polymicrobial bacterial communities demonstrated that age was associated with only subtle shifts in ecological composition, but an overabundance of genomic virulence factors that have functional consequence on host immune evasion. One Sentence SummaryThe severity of sepsis in the aged host is in part mediated by longevity-associated increases in gut microbial virulence.

microbiology↗

bioRxiv2023

Urinary Glycosaminoglycans are Associated with Recurrent UTI and Urobiome Ecology in Postmenopausal Women

Glycosaminoglycans (GAGs) are linear, negatively charged polysaccharides composed of repeating disaccharide units of uronic acid and amino sugars. The luminal surface of the bladder epithelium is coated with a GAG layer. These urothelial GAGs are thought to provide a protective barrier and serve as a potential interaction site with the urinary microbiome (urobiome). Previous studies have profiled urinary GAG composition in mixed cohorts, but the urinary GAG composition in postmenopausal women remains undefined. To investigate the relationship between GAGs and recurrent UTI (rUTI), we profiled urinary GAGs in a controlled cohort of postmenopausal women. We found that chondroitin sulfate (CS) is the major urinary GAG in postmenopausal women and that urinary CS was elevated in women with active rUTI. We also associated urinary GAGs with urobiome composition and identified bacterial species that significantly associated with urinary GAG concentration. Corynebacterium amycolatum, Porphyromonas somerae, and Staphylococcus pasteuri were positively associated with heparin sulfate or hyaluronic acid and bacterial species associated with vaginal dysbiosis were negatively correlated to urinary CS. Altogether, this work defines changes in urinary GAG composition associated with rUTI and identifies new associations between urinary GAGs and the urobiome that may play a role in rUTI pathobiology.

biochemistry↗

bioRxiv2022

Conserved FimK truncation coincides with increased expression of type 3 fimbriae and cultured bladder epithelial cell association in Klebsiella quasipneumoniae

Klebsiella spp. commonly cause both uncomplicated urinary tract infection (UTI) and recurrent UTI (rUTI). Klebsiella quasipneumoniae, a relatively newly defined species of Klebsiella, has been shown to be metabolically distinct from Klebsiella pneumoniae, but its urovirulence mechanisms have not been defined. K. pneumoniae uses both type 1 and type 3 fimbriae to attach to host epithelial cells. The type 1 fimbrial operon is well-conserved between Escherichia coli and K. pneumoniae with the exception of fimK, which is unique to Klebsiella spp. FimK contains an N-terminal DNA binding domain and a C-terminal phosphodiesterase (PDE) domain that has been hypothesized to cross-regulate type 3 fimbriae expression via modulation of cellular levels of cyclic di-GMP. Here, we find that a conserved premature stop codon in K. quasipneumoniae fimK results in truncation of the C-terminal PDE domain and that the bladder epithelial cell association and invasion of uropathogenic K. quasipneumoniae strain KqPF9 is dependent on type 3 but not type 1 fimbriae. Further, we show that basal expression of both type 1 and type 3 fimbrial operons as well as bladder epithelial cell association is elevated in KqPF9 relative to uropathogenic K. pneumoniae TOP52 and that complementation of KqPF9{Delta}fimK with the TOP52 fimK allele reduced type 3 fimbrial expression and bladder epithelial cell attachment. Taken together these data suggest that the C-terminal PDE of FimK can modulate type 3 fimbrial expression in K. pneumoniae and its absence in K. quasipneumoniae may lead to a loss of type 3 fimbrial cross-regulation. ImportanceK. quasipneumoniae is often indicated as the cause of many opportunistic infections including urinary tract infection (UTI), which affects >50% of women worldwide. However, virulence mechanisms of K. quasipneumoniae remain uninvestigated. Prior to this work, K. quasipneumoniae and K. pneumoniae had only been distinguished phenotypically by metabolic differences. This work contributes to the understanding of K. quasipneumoniae virulence phenotypes by evaluating the contribution of type 1 and type 3 fimbriae, which are critical colonization factors encoded by all Klebsiella spp., to K. quasipneumoniae bladder epithelial cell attachment. We identify clear phenotypic differences in both bladder epithelial cell attachment between uropathogenic K. pneumoniae and K. quasipneumoniae. Importantly, we find that a structural difference in the fimbrial regulatory gene fimK may contribute to differential co-regulation of type 1 and type 3 fimbriae between the two Klebsiella species.

microbiology↗

bioRxiv2021

Recurrent urinary tract infection and estrogen shape the taxonomic ecology and functional potential of the postmenopausal urobiome

Community-acquired urinary tract infection (UTI) is among the most common bacterial infections observed in humans. Postmenopausal women are a rapidly growing and underserved demographic group who are severely affected by recurrent UTI (rUTI) with a >50% recurrence rate. In this population, rUTI can persist for years, reducing quality of life and imposing a significant healthcare burden. rUTI is most often treated by antibiotics, but development of antibiotic resistance and allergy limit therapeutic options. The female urinary microbiome (urobiome) has been identified as a key component of the urogenital environment. However, compositional and functional changes in the urobiome underlying rUTI susceptibility in postmenopausal women are not well understood. Here, we used a controlled, cross-sectional cohort of postmenopausal women, to interrogate changes in urobiome structure and function linked to rUTI susceptibility by whole genome metagenomic sequencing (WGMS), advanced urine culture, estrogen metabolite profiling, and antibiotic sensitivity testing. Overall, we detected 276 bacterial, archaeal, and fungal species representing 106 genera. We find a putative commensal population consisting of species known to protect against bacterial vaginosis, such as Lactobacillus crispatus, within the urobiome of postmenopausal women who do not experience UTI. Integration of clinical metadata detected an almost exclusive enrichment of lactobacilli, including L. crispatus and L. vaginalis, in women taking estrogen hormone therapy (EHT). Integrating quantitative metabolite profiling of urinary estrogens with WGMS, we observed robust correlations between urobiome taxa, such as Bifidobacterium breve and L. crispatus, and urinary estrogen conjugate concentrations in women with no history of UTI that were absent in women with rUTI history. We further used functional metagenomic profiling and patient-derived isolate phenotyping to identify microbial metabolic pathways, antimicrobial resistance genes (ARGs), and clinically relevant antimicrobial resistance phenotypes enriched between disease-states. Our data indicate that distinct urobiome metabolic and ARG signatures are associated with current rUTI status and history. Importantly, we observed that rUTI history leaves an imprint of enriched ARGs even in women not currently experiencing UTI. Taken together, our data suggests that rUTI history and estrogen strongly shape the functional and taxonomic composition of the urobiome in postmenopausal women.

microbiology↗

bioRxiv2020

Manipulation of IRE1-dependent MAPK signaling by a Vibrio agonist-antagonist effector pair

Diverse bacterial pathogens employ effector delivery systems to disrupt vital cellular processes in the host (1). The type III secretion system 1 of the marine pathogen, Vibrio parahaemolyticus, utilizes the sequential action of four effectors to induce a rapid, pro-inflammatory cell death uniquely characterized by a pro-survival host transcriptional response (2, 3). Herein, we show that this pro-survival response is caused by the action of the channel-forming effector VopQ that targets the host V-ATPase resulting in lysosomal deacidification and inhibition of lysosome-autophagosome fusion. Recent structural studies have shown how VopQ interacts with the V-ATPase and, while in the ER, a V-ATPase assembly intermediate can interact with VopQ causing a disruption in membrane integrity. Additionally, we observe that VopQ-mediated disruption of the V-ATPase activates the IRE1 branch of the unfolded protein response (UPR) resulting in an IRE1-dependent activation of ERK1/2 MAPK signaling. We also find that this early VopQ-dependent induction of ERK1/2 phosphorylation is terminated by the VopS-mediated inhibitory AMPylation of Rho GTPase signaling. Since VopS dampens VopQ-induced IRE1-dependent ERK1/2 activation, we propose that IRE1 activates ERK1/2 phosphorylation at or above the level of Rho GTPases. This study illustrates how temporally induced effectors can work as in tandem as agonist/antagonist to manipulate host signaling and reveal new connections between V-ATPase function, UPR and MAPK signaling. ImportanceVibrio parahaemolyticus (V. para) is a seafood-borne pathogen that encodes two Type 3 Secretion Systems (T3SS). The first system T3SS1 is thought to be maintained in all strains of V. para to to maintain survival in the environment, whereas the second sytem T3SS2 is linked to clinical isolates and disease in humans. Herein, we find that first system targets evolutionarily conserved signaling systems to manipulate host cells, eventually causing a rapid, orchestrated cells death within three hours. We have found that the T3SS1 injects virulence factors that temporally manipulate host signaling. Within the first hour of infection, the effector VopQ acts first by activating host surval signals while diminishing the host cell apoptotic machinery. Less than an hour later, another effector VopS reverses activation and inhibition of these signaling systems ultimately leading to death of the host cell. This work provides example of how pathogens have evolved to manipulate the interplay between T3SS effectors to regulate host signaling pathways.

microbiology↗

bioRxiv2020

A Whole Cell Metal-Organic Framework Encapsulated Vaccine Against Septicemic UPEC Infection

The increasing rate of resistance of bacterial infection against antibiotics requires next generation approaches to fight potential pandemic spread. The development of vaccines against pathogenic bacteria has been difficult owing, in part, to the genetic diversity of bacteria. Hence, there are many potential target antigens and little a priori knowledge of which antigen/s will elicit protective immunity. The painstaking process of selecting appropriate antigens could be avoided with whole-cell bacteria; however, whole-cell formulations typically fail to produce long-term and durable immune responses. These complications are one reason why no vaccine against any type of pathogenic E. coli has been successfully clinically translated. As a proof of principle, we demonstrate a method to enhance the immunogenicity of a model pathogenic E. coli strain by forming a slow releasing depot. The E. coli strain CFT073 was biomimetically mineralized within a metal-organic framework (MOF). This process encapsulates the bacteria within 30 minutes in water and at ambient temperatures. Vaccination with this new formulation substantially enhances antibody production and results in significantly enhanced survival in a mouse model of bacteremia compared to standard inactivated formulations.

immunology↗

bioRxiv2019

FIMBRIAE AND FLAGELLA MEDIATED SURFACE MOTILITY AND THE EFFECT OF GLUCOSE ON NONPATHOGENIC AND UROPATHOGENIC ESCHERICHIA COLI

We characterized the surface motility of nonpathogenic and pathogenic E. coli strains with respect to the appendage requirement, flagella versus fimbriae, and the glucose requirement. Nonpathogenic lab strains exhibited either slow or fast surface movement. The slow strains required type 1 fimbriae for movement, while the fast strains required flagella and had an insertion in the flhDC promoter region. Surface movement of three uropathogenic E. coli (UPEC) strains was fast and required flagella, but these strains did not have an insertion in the flhDC promoter region. We assessed swimming motility as an indicator of flagella synthesis and found that glucose inhibited swimming of the slow nonpathogenic strains but not of the fast nonpathogenic or pathogenic strains. Fimbriae-based surface motility requires glucose, which inhibits cyclic-AMP (cAMP) and flagella synthesis; therefore, we examined whether surface motility required cAMP. The surface motility of a slow, fimbriae-dominant, nonpathogenic strain did not require cAMP, which was expected because fimbriae synthesis does not require cAMP. In contrast, the surface motility of a faster, flagella-dominant, UPEC strain required cAMP, which was unexpected because swarming was unaffected by the presence of glucose. Electron microscopy verified the presence or absence of fimbriae or flagella. In summary, surface motilities of the nonpathogenic and uropathogenic E. coli strains of this study differed in the appendage used and the effects of glucose on flagella synthesis. IMPORTANCEUropathogenic Escherichia coli strains cause 80-90% of community-acquired urinary tract infections, and recurrent urinary tract infections, which can last for years, and often become antibiotic resistant. Urinary tract infections can be associated with intra-vesical lesions extending from localized trigonitis/cystitis to widely distributed pancystitis: motility may be a factor that distinguishes between these infection patterns. Nonpathogenic and uropathogenic E. coli were shown to exhibit fimbriae- and flagella-dependent surface motility, respectively, and the difference was attributed to altered control of flagella synthesis by glucose. Uropathogenic E. coli strains grow more rapidly in urine than nonpathogenic strains, which implies differences in metabolism. Understanding the basis for glucose-insensitive control of flagella-dependent motility could provide insight into uropathogenic E. coli metabolism and virulence.

microbiology↗