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Antibodies against E. coli O-antigens and common enterobacterial antigen in kidney-transplant recipients. Comparison of antibody findings with evidence of urinary tract infection.

Using indirect haemagglutination, sera from 45 patients who had undergone renal transplantation were examined for 0-antibodies against 10 selected uropathogenic E. coli strains, and against common enterobacterial antigen (anti-CA). Bilateral nephrectomy was carried out, usually less than three months after transplantation, and serum from the time of nephrectomy was examined. The aim was to correlate antibody findings with evidence of urinary tract infection (UTI), as assessed by significant bacteriuria or growth of bacteria from the nephrectomy specimens. All the sera contained antibodies against several of the E. coli strains, mostly in titres less than or equal to 160, but titres up to 5120 occurred. No statistically significant correlation was found between the occurrence of high titres of type-specific 0-antibodies to E. coli and evidence of E. coli UTI. In contrast, anti-CA-present in the sera of 19 patients, mostly in titres of 10-40-occured with significantly increased frequency in patients with E. coliuria before transplantation and in patients with growth of E. coli from the nephrectomy specimens. It is concluded that anti-CA-even in low titres-appeared to give a better serological parameter of E. coli UTI than screening for antibodies against the selected uropathogenic E. coli strains.

Adolescent

Oxidative stress induces E. coli aryl polyene expression, sensitizing the bacterial stress response and modulating the redox environment of innate immune cells.

UNLABELLED: Aryl polyenes (APEs) are specialized polyunsaturated outer membrane lipids that protect their producers from oxidative stress and contribute to biofilm formation. APEs are produced by an abundant biosynthetic gene cluster (BGC) family conserved across Gram-negative bacterial clades. The APE biosynthesis pathway involves 11 different enzymes and culminates in the attachment of APEs to an anchor molecule in the Gram-negative outer membrane. Unlike most other small molecule BGCs, the APE BGC does not contain a dedicated regulatory gene that controls the production of its metabolically costly compounds. Building from our prior observations of APEs' role in acute oxidative stress protection, we use a uropathogenic Escherichia coli (UPEC) strain to show that APE expression conveys a potential competitive advantage characterized by increased early-stage growth, sensitization of the bacterial oxidative stress response, and dampening of the redox stress of innate immune cells after in vitro infection. Our data indicate that APEs could act as a UPEC fitness factor, and in future work, we aim to study their contribution to overall bacterial pathogenicity and survival, as well as how APEs could facilitate the transition from an oxygen-poor environment, such as the gut, to the oxygen-rich environment of the urinary tract. IMPORTANCE: Bacterial pathogens use various mechanisms to achieve a competitive advantage under harsh conditions, such as during interactions with their host. We studied the function of aryl polyenes (APEs), specialized polyunsaturated fatty acids in the outer membrane, in the context of a uropathogenic E. coli strain. APE expression is induced by an oxidative environment and contributes to early-stage growth and sensitization of the oxidative stress response. Furthermore, APE-expressing E. coli dampen the intracellular oxidative milieu of target host phagocytes. These findings suggest a role for APEs as a fitness factor and create opportunities to study their in vivo function and explore them as a potential drug target.

Oxidative Stress

[Cytopathogenic action of E. coli strains, containing corresponding ABO type heterogeneous antigens, on transplantable human cells].

A study was made (in vitro) of the interaction of various strains of E. coli, serological type O26 with continuous human cells (HeLa, Tg-33 and RH). Phenomenon of the cytopathogenic action of uropathogenic E. coli strains, containing heterogenous antigens, type O(H) and B, on the human cell strains possessing corresponding isoantigens was revealed on the 6th hour of the interaction. The number of dead cells in these cultures exceeded (1.5--3 times) their count cultures to which E. coli containing no heterogenous antigens or containing different human heterogenous antigens of the ABO type were added. It is supposed that this phenomenon played an important role in the development of chronic forms of colibacterial pyelonephritis.

ABO Blood-Group System

Strain-level differences in Gardnerella urinary tract persistence and pathogenesis are consistent with comparative phylogenomic analyses.

BACKGROUND: Gardnerella is a genus of gram variable anaerobic bacteria that is commonly present in the female urogenital tract, especially during bacterial vaginosis (BV). BV is linked with increased risk of urinary tract infections (UTI) and Gardnerella has been frequently detected in urine collected directly from the bladder. Understanding the contribution of Gardnerella to urogenital pathogenesis has been complicated by its genetic heterogeneity and a shortage of data from in vivo models. Recently, a clinical isolate of Gardnerella displayed covert pathogenesis in a mouse urinary tract inoculation model, triggering urothelial exfoliation and promoting UTI by uropathogenic E. coli. Data from clinical studies suggests differential association of Gardnerella phylogenetic clades with BV or urogenital infections. In vitro data has demonstrated heterogeneity in the presence and expression of putative virulence determinants between Gardnerella strains. This study was designed to compare diverse Gardnerella strains in vivo to identify genomic variation associated with urinary tract persistence and pathogenesis. METHODS: Eighteen Gardnerella clinical isolates from each of the four main phylogenetic clades were individually inoculated transurethrally into female C57BL/6 mice. Bacteriuria was monitored by quantitative culturing of Gardnerella in urine. Pathologic features were assessed by immunofluorescent and histological staining of bladder tissues. Pan-genome phylogenetic analyses were performed on the 18 Gardnerella isolates used for mouse infections to identify accessory genes that were associated with observable in vivo phenotypes, including long and short-term persistence, urothelial exfoliation and bladder edema. Genes that were significantly associated to phenotype were then matched against a pangenome analysis of 291 publicly available Gardnerella genomes to determine the conservation of these putative colonization and virulence factors across the genus. RESULTS: Gardnerella strains displayed clear differences in persistence and pathogenesis in the mouse bladder that were congruent with phylogeny. Clade 2 strains were more persistent in the urinary tract whereas strains from the other three clades either caused transient bacteriuria or were undetectable. Strains from clade 2 and 4 induced urothelial exfoliation while edema was triggered by strains from clades 2, 3 and 4. Pangenome analyses revealed 45 genes that were associated with in vivo persistence and pathogenicity. Among the wider 291 publicly available genomes, clade 2 strains encoded more of the genes associated with bacteriuria phenotypes compared to strains in the other three clades. Exfoliation-associated genes were present in most clade 4 strains. Clade 3 strains lack most of the in vivo-associated genes, whereas clade 1 strains were more heterogenous. CONCLUSIONS: This study provides in vivo evidence for differential urinary tract colonization and pathogenesis by strains from different clades/species within the genus Gardnerella and identifies new putative persistence and virulence factors. Utilizing the in vivo data from tested strains, pangenome analyses predicts that clade 2 Gardnerella are the most likely to persist in the urinary tract and that clades 2 and 4 have the highest uropathogenic potential. These findings inform future targeted screening and treatment approaches aimed at limiting harmful Gardnerella urinary tract exposures.

Journal Article

Inherited Susceptibility to Urinary Tract Infections from Kidney Papilla to Bladder.

Urinary tract infections (UTIs) are traditionally viewed as environmentally driven, yet their inherited susceptibility remains largely unexplored. We conducted a cross-biobank genome-wide association study of recurrent UTIs in 1,860,836 individuals (213,869 cases and 1,646,967 controls). We identified 36 genetic susceptibility loci and performed tissue-based multi-omic mapping to prioritize candidate causal genes. UTI risk alleles preferentially modulated epithelial gene expression in kidney and bladder, converging on urinary epithelia structure and function. PSCA, encoding a secreted epithelial surface protein, emerged as the strongest candidate under genetic control; the gene product is constitutively secreted into the urine from kidney papilla and bladder epithelia, binds uropathogenic E. coli, and inhibits bacterial growth in vitro. Our findings define the polygenic architecture of UTIs and highlight the critical role of uroepithelial surface defenses, providing a new framework for host-directed, non-antibiotic interventions.

Journal Article

In vivo CRISPRi screens reveal Escherichia coli functional adaptations in the mouse gut.

Escherichia coli exhibits remarkable genetic diversity that enables it to adapt to the intestinal environment. Here we establish an in vivo CRISPR interference platform that leverages bacterial gene fitness as a high-resolution functional reporter of E. coli adaptations within mice harbouring a defined minimal microbial community (OligoMM12). The screen revealed that diet profoundly shapes the metabolic landscape of E. coli and the essential gene profile identified cross-feeding interactions. Comparison between a laboratory strain (MG1655), a uropathogenic strain (CFT073) and an adherent-invasive E. coli (AIEC LF82) identified distinct genetic requirements for intestinal colonization, highlighting divergent motility, stress response and respiration strategies. In a host inflammatory environment, we found that AIEC LF82 preferably colonized the small intestine with a mobile genetic element, Gally prophage, playing an important role in modulating fitness. These findings provide a high-resolution genetic atlas of E. coli's functional adaptation and demonstrate the utility of functional genomics to probe the gut environment itself.

Journal Article

[The periurethral flora in female patients with recurrent urinary tract infection (UTI) (author's transl)].

In 52 girls and 38 women with recurrent nonobstructive UTI 529 bacterial samples were obtained from the periurethral area under the following conditions: no bacteriuria and no chemotherapy for at least 3 weeks before the examination. In 225 samples we found E. coli and enterococci as the most frequent potentially uropathogenic bacteria. In the periurethral region these were found approximately twice as frequently as in urologically normal persons. 36 (40%) of the patients had no further recurrences during the follow-up, though 107 (44%) of the swabs showed an abnormal bacterial colonization. 54 (60%) of the patients, many of them with very frequent recurrences, in only 118 (41%) of the obtained samples showed an abnormal periurethral flora. The findings suggest that the periurethral flora is not the most important factor in the pathogenesis of UTI.

Adolescent

Phenotype-genotype discordance in antimicrobial resistance profiles of Gram-negative uropathogens recovered from catheter-associated urinary tract infections in Egypt.

OBJECTIVES: Catheter-associated urinary tract infections (CAUTIs) are among the most common healthcare-associated infections in low- and middle-income countries (LMICs), but there are few resistome data available for relevant uropathogens. The goal of this study was to characterize the antimicrobial resistance (AMR) phenotypes and genotypes of a large collection of Gram-negative bacteria recovered from CAUTIs in a hospital in Mansoura, Egypt. METHODS: Phenotypic AMR profiles and whole-genome sequence data were generated for 132 isolates. Resistomes were predicted using ResFinder, CARD and AMRFinder. Similarity of uropathogen genomic data was determined using sourmash (kmer signatures). Escherichia coli genomic data were subject to a pangenome analysis using Panaroo. RESULTS: Sixty-seven E. coli (Phylogroup B2; 53.7%, 36/67), 14 Pseudomonas aeruginosa, 11 Klebsiella pneumoniae, 9 Proteus mirabilis, 8 Providencia spp., 5 Enterobacter hormaechei and 18 rare CAUTI-associated isolates were identified. Several (22/132) isolates were multidrug-resistant, while almost half (62/132) were extensively drug-resistant. Phenotype-genotype discordance was found to be an important consideration in resistome studies in Egypt, with a total concordance of 91% (1115/1225), 85.7% (1273/1485) and 80.5% (1196/1485) for ResFinder, CARD and AMRFinder, respectively. Pseudomonas, at the species level, exhibited the greatest discordance. At the antimicrobial level, meropenem was subject to greatest discordance. New AMR variants were found for Egypt for Pseudomonas (blaOXA-486, blaOXA-488, blaOXA-905, blaIMP-43, blaPDC-35, blaPDC-45, blaPDC-201) and E. coli (blaTEM-176, blaTEM-190). CONCLUSIONS: This study shows that there is phenotype-genotype discordance in AMR profiling among CAUTI isolates, highlighting the need for comprehensive approaches in resistome studies. We also show the genomic diversity of Gram-negative uropathogens contributing to disease burden in a little-studied LMIC setting.

Egypt

Snapshot Genomic Surveillance Reveals Insights into Antimicrobial Resistance and Lineage Diversity of Uropathogens in Older Adults in Queensland.

BACKGROUND: Community-acquired urinary tract infections (UTIs) are a significant health concern in older adults. However, few studies have investigated the epidemiology of uropathogens across diverse settings where older adults reside. METHODS: In this study, we whole-genome sequenced urinary isolates of Escherichia coli, Klebsiella species, and Enterobacter cloacae complex collected from individuals aged 70 and over living in the community and residential aged care facilities (RACFs) in Queensland, Australia. We investigated the prevalence of antimicrobial resistance (AMR), pathogen population structure, and transmission dynamics across the settings. RESULTS: E. coli was most frequently identified (82.2%, 447/544), followed by K. pneumoniae (10.8%, 59/544) and E. hormaechei (2.6%, 14/544). Intraspecies lineages were diverse, and a total of 177 sequence types were identified. The three predominant lineages were E. coli ST73 (10.7%, 54/504), ST95 (8.1%, 41/504), and ST131 (5.4%, 27/504). Transmission events were minimal, being identified in 13 patients (2.5%), mainly from the community. The resistance rate to antibiotics was low, with only a small proportion (9.7%) of multidrug-resistant (MDR) isolates. The predominant MDR lineage was E. coli ST131, which carried extended-spectrum beta-lactamase bla CTX-M genes. CONCLUSIONS: Community-acquired UTIs in older adults are predominantly caused by diverse E. coli lineages, with limited evidence of transmission within aged care facilities. The low rates of AMR in the community, along with the absence of strains adapted to a particular setting, suggest that current empiric therapy guidelines remain appropriate. Our prospective genomic surveillance offers valuable insights for monitoring UTIs in this population. It demonstrates the importance of an unbiased approach to accurately capture the prevalence and diversity of uropathogen lineages.

Enterobacteriaceae

Rapid inference of antibiotic susceptibility phenotype of uropathogens using metagenomic sequencing with neighbor typing.

UNLABELLED: Timely diagnostic tools are needed to improve antibiotic treatment. Pairing metagenomic sequencing with genomic neighbor typing algorithms may support rapid clinically actionable results. We created resistance-associated sequence elements (RASE) databases for Escherichia coli and Klebsiella spp. and used them to predict antibiotic susceptibility in directly sequenced (Oxford Nanopore) urine specimens from critically ill patients. RASE analysis was performed on pathogen-specific reads from metagenomic sequencing. We evaluated the ability to predict (i) multi-locus sequence type (MLST) and (ii) susceptibility profiles. We used neighbor typing to predict MLST and susceptibility phenotype of E. coli (64/80) and Klebsiella spp. (16/80) from urine samples. When optimized by lineage score, MLST predictions were concordant for 73% of samples. Similarly, a RASE-susceptible prediction for a given isolate was associated with a specificity and a positive likelihood ratio (LR+) for susceptibility of 0.65 (95% CI, 0.54-0.76) and 2.26 (95% CI, 1.75-2.92), respectively, with an increase in the probability of susceptibility of 10%. A RASE-non-susceptible prediction was associated with a sensitivity and a negative likelihood ratio (LR-) for susceptibility of 0.79 (95% CI, 0.74-0.84) and 0.32 (95% CI, 0.24-0.43) respectively, with a decrease in the probability of susceptibility of 20%. Numerous antibiotic classes could reasonably be reconsidered empiric therapy by shifting empiric probabilities of susceptibility across relevant treatment thresholds. Moreover, these predictions can be available within 6 h. Metagenomic sequencing of urine specimens with neighbor typing provides rapid and informative predictions of lineage and antibiotic susceptibility with the potential to impact clinical decision-making. IMPORTANCE: Urinary tract infections (UTIs) are a common diagnosis in hospitals and are often treated empirically with broad-spectrum antibiotics. These broad-spectrum agents can select for resistance in these bacteria and co-colonizing organisms. The use of narrow-spectrum agents is desirable as an antibiotic stewardship measure; however, it is counterbalanced by the need for adequate therapy. Identification of causative organisms and their antibiotic susceptibility can help direct treatment; however, conventional testing requires days to produce actionable results. Methods to quickly and accurately predict susceptibility phenotypes for pathogens causing UTI could thus improve both patient outcomes and antibiotic stewardship. Here, expanding on previous work showing accurate prediction for certain Gram-positive pathogens, we demonstrate how the use of RASE from metagenomic sequencing can provide informative and rapid phenotype prediction results for common Gram-negative pathogens in UTI, highlighting the future potential of this method to be used in clinical settings to guide empiric antibiotic selection.

Humans