Enteropathogenic escherichia coli infection in children

Indole signaling in Escherichia coli: a target for antivirulence therapy?

Pathogenic Escherichia coli are a major cause of infections in both humans and animals, leading to conditions such as severe diarrheal diseases, urinary tract infections, enteritis, and septicemia. To combat bacterial infections, antibiotics are widely utilized. However, the extensive and inappropriate use of antibiotics has fueled the development and spread of antibiotic resistance, posing a significant challenge to the effective treatment of E. coli. There is consequently an urgent need to explore alternative therapies to control such infections. This review provides an overview of the recent findings concerning indole signaling in E. coli. E. coli uses indole as a quorum sensing molecule, and indole signaling has been reported to decrease various virulence factors in pathogenic E. coli, including motility, biofilm formation, adherence to host cells, expression of the LEE pathogenicity island, and formation of attaching and effacing lesions. This makes indole signaling an interesting target for the development of new therapeutics in the framework of antivirulence therapy. Both natural and synthetic indole analogues have been explored as potential virulence inhibitors. This alternative approach could be advantageous, as it will exert less selective pressure for resistance development than conventional antibiotics.

Chemical synthesis of conjugation-ready tetrasaccharide repeating unit of Escherichia coli O50 O-antigen

Escherichia coli is a rod-shaped Gram-negative bacterium notorious for provoking diverse human infections. In this study, we report the first total synthesis of tetrasaccharide repeating unit of the cell wall of Gram-negative bacteria Escherichia coli O50 augmented with aminoethyl linker, employing both linear [1+1+1+1] and one-pot [1+1+2] approaches, and later one providing the better yield. As an aminoethyl linker, it can be further utilized for biological purposes; the challenging cis (1 → 4)-β-glycosidic linkage between l-rhamnose and d-glucosamine is addressed here with high stereo control.

Human milk oligosaccharide secretion dynamics during breastfeeding and its antimicrobial role: A systematic review

BACKGROUND

Human milk oligosaccharides (HMOs) are bioactive components of breast milk with diverse health benefits, including shaping the gut microbiota, modulating the immune system, and protecting against infections. HMOs exhibit dynamic secretion patterns during lactation, influenced by maternal genetics and environmental factors. Their direct and indirect antimicrobial properties have garnered significant research interest. However, a comprehensive understanding of the secretion dynamics of HMOs and their correlation with antimicrobial efficacy remains underexplored.

AIM

To synthesize current evidence on the secretion dynamics of HMOs during lactation and evaluate their antimicrobial roles against bacterial, viral, and protozoal pathogens.

METHODS

A systematic search of PubMed, Scopus, Web of Science, and Cochrane Library focused on studies investigating natural and synthetic HMOs, their secretion dynamics, and antimicrobial properties. Studies involving human, animal, and in vitro models were included. Data on HMO composition, temporal secretion patterns, and mechanisms of antimicrobial action were extracted. Quality assessment was performed using validated tools appropriate for study design.

RESULTS

A total of 44 studies were included, encompassing human, animal, and in vitro research. HMOs exhibited dynamic secretion patterns, with 2′-fucosyllactose (2′-FL) and lacto-N-tetraose peaking in early lactation and declining over time, while 3-fucosyllactose (3-FL) increased during later stages. HMOs demonstrated significant antimicrobial properties through pathogen adhesion inhibition, biofilm disruption, and enzymatic activity impairment. Synthetic HMOs, including bioengineered 2′-FL and 3-FL, were structurally and functionally comparable to natural HMOs, effectively inhibiting pathogens such as Pseudomonas aeruginosa , Escherichia coli , and Campylobacter jejuni . Additionally, HMOs exhibited synergistic effects with antibiotics, enhancing their efficacy against resistant pathogens.

CONCLUSION

HMOs are vital in antimicrobial defense, supporting infant health by targeting various pathogens. Both natural and synthetic HMOs hold significant potential for therapeutic applications, particularly in infant nutrition and as adjuncts to antibiotics. Further research, including clinical trials, is essential to address gaps in knowledge, validate findings, and explore the broader applicability of HMOs in improving maternal and neonatal health.

Comparative analysis of diarrheagenic and uropathogenic Escherichia coli isolates: antimicrobial resistance, virulence, and genomic profiling

AIMS

Escherichia coli is a key pathogen causing gastrointestinal and urinary tract infections. Diarrheagenic E. coli (DEC) and uropathogenic E. coli (UPEC) are distinct major pathotypes linked to specific clinical outcomes. Therefore, this study aimed to compare DEC and UPEC isolates regarding distribution, antimicrobial resistance, serotypes, resistance, and virulence gene profiles.

MATERIALS AND METHODS

A total of 400 clinical samples (200 stools and 200 urine) were analyzed using phenotypic and genotypic methods. Antimicrobial resistance, serotyping, and detection of resistance and virulence genes were performed. Phylogenetic and correlation analyses were conducted to explore genetic relationships and interactions.

RESULTS

Of 97 E. coli isolates (24.25% prevalence), 56 DEC and 41 UPEC were detected. DEC isolates primarily included serotypes O26, O45, and O55, while UPEC predominantly featured O1 and O25. UPEC showed higher multidrug resistance, while DEC was more virulent. UPEC carried unique markers (ureC, papC), and DEC harbored stx and aggR genes associated with gastrointestinal infections. Phylogenetic analysis showed separate clustering for DEC and UPEC, with limited genetic overlap. Correlation analysis identified strong associations within resistance and virulence genes but a negative correlation between these traits.

CONCLUSION

This study compared the phenotypic and genetic features of DEC and UPEC, highlighting their distinct pathogenic traits. Limited genetic overlap suggests potential gene transfer, influencing adaptability, and evolution.

Formation of a membraneless compartment regulates bacterial virulence

The RNA-binding protein CsrA regulates the expression of hundreds of genes in several bacterial species, thus controlling virulence and other processes. However, the outcome of the CsrA-mRNA interactions is modulated by competing small RNAs and other factors through mechanisms that are only partially understood. Here, we show that CsrA accumulates in a dynamic membraneless compartment in cells of E. coli and other pathogenic species. In addition to CsrA, the compartment contains components of the RNA-degrading complex (degradosome), regulatory small RNAs, and selected mRNAs. Formation of the compartment is associated with a switch between promoting and repressing virulence gene expression by CsrA. We suggest that similar CsrA switches may be widespread in diverse bacteria.

On the role of the sorting platform in hierarchical type III secretion regulation in enteropathogenic Escherichia coli

The virulence of enteropathogenic Escherichia coli (EPEC) depends on a type III secretion system (T3SS), a membrane-spanning apparatus that injects effector proteins into the cytoplasm of target enterocytes. The T3SS, or injectisome, is a self-assembled nanomachine whose biogenesis and function rely on the ordered secretion of three distinct categories of proteins: early, middle, and late type III substrates. In EPEC, this hierarchical secretion is assisted by several cytosolic protein complexes at the base of the injectisome. Among these, the sorting platform is involved in the recognition and sequential loading of the different classes of T3-substrates. In addition, a heterotrimeric gatekeeper complex, also known as a molecular switch, operates in concert with components of the T3SS export apparatus to guarantee the delivery of middle substrates prior to late substrate secretion. In this study, we showed that the sorting platform is differentially required for the secretion of distinct categories of substrates. Moreover, we demonstrated a cooperative interplay and protein-protein interactions between the sorting platform and the gatekeeper complex for proper middle and late substrate docking and secretion. Overall, our results provide new insights into the intricate molecular mechanisms that regulate protein secretion hierarchy during T3SS assembly.IMPORTANCEEnteropathogenic Escherichia coli employs a type III secretion system to deliver virulence proteins directly into host cells, disrupting multiple cellular processes to promote infection. This multiprotein system assembles in a precise stepwise manner, with specific proteins being recruited and secreted at distinct stages. The sorting platform and the gatekeeper complex play critical roles in regulating this process, but their cooperative mechanism has not been fully elucidated. Here, we reveal a novel functional interaction between these two components, which is critical for hierarchical substrate recognition and secretion. These findings advance our understanding of the molecular mechanisms underlying bacterial virulence and suggest new potential targets for antimicrobial strategies aimed at disrupting T3SS function.

Production and Functional Evaluation of Recombinant Active Peptide RH in Pichia Pastoris: Protection Against Escherichia Coli Induced Cell Death

In the gastro-intestinal tract, Escherichia coli (E.coli) infections can trigger programmed cell death of intestinal epithelial cells, through mechanisms such as oxidative stress and ferroptosis, which compromise gut barrier integrity. Given the rising prevalence of antibiotic-resistant E. coli strains, there is an urgent need to develop innovative antimicrobial therapies that go beyond conventional antibiotics. Antimicrobial peptides represent a promising alternative for combating resistant bacterial strains due to their dual role in antimicrobial activity and immune modulation. In this study, we constructed multiple expression cassettes to express porcine β-defensin 2 (PBD2)-derived peptide RH in Pichia pastoris (P. pastoris), purified the peptide using nickel column affinity chromatography, and assessed its in vivo and in vitro activity. The results indicated that under the optimal condition (3% methanol), the total secreted protein concentration reached 306.5 mg/L after 120 h of fermentation. Following purification, the yield of recombinant active peptide RH (rRH) can reached 59.34 mg/L. The rRH exhibits strong antimicrobial activity and resistance to oxidation, and by inhibiting oxidative stress-mediated ferroptosis it reduces E. coli-induced cell death and injury in the jejunum. This dual functionality of rRH positions it as a potential therapeutic candidate for treating gastrointestinal infections and improving gut health, providing a crucial alternative to traditional antibiotics.

Enteropathogenic E. coli effector Map interacts with Rab13 and regulates the depletion of the tight junction proteins occludin and claudins via cathepsin B-mediated mechanisms

Infections by enteropathogenic Escherichia coli (EPEC) cause acute diarrheal disease in infants accounting for severe morbidity and mortality. One of the underlying causes of the disease is the breakdown of the intestinal barrier maintained by the tight junctions (TJs). EPEC uses a type 3 secretion system to translocate more than 20 effectors into infected cells, which disrupt several functions of the host cells. The effectors EspF, Map, EspG1/G2 and NleA have been reported to disrupt the TJs causing the leakage of charged ions and uncharged molecules through the barrier. We have previously reported that EspF and Map cause the depletion of TJ proteins claudin-1, claudin-4 and occludin through both transcriptional and post-transcriptional mechanisms. Here, we show that the inhibition of the lysosomal protease cathepsin B, in cells expressing the EPEC effector Map, reduces the depletion of claudin-1, claudin-4 and occludin. Further, we show that the expression of a mutant Map protein lacking the mitochondrial targeting sequence inhibits the depletion of occludin and its delocalization from the TJs and partially rescues claudin-4 levels and its junctional localization. We also identified a novel interaction of Map with the GTPase Rab13. Rab13 has been reported to mediate the recycling of occludin to the plasma membrane. Since occludin regulates the passage of macromolecules through the intestinal TJ barrier, the interaction of Map with Rab13 may have important implications for the loss of TJ integrity and excessive leakage through the intestinal barrier in EPEC pathogenesis.

Combating enteropathogenic and multidrug resistant Escherichia coli using the lytic bacteriophage vB_EcoM_ECO78, which disrupts bacterial biofilm formation and exhibits a remarkable environmental stability

AIM

The current study aimed to establish a phenotypic and genotypic characterization record of a novel lytic bacteriophage (phage) against multidrug-resistant (MDR) Escherichia coli (E. coli) infections.

METHODS AND RESULTS

Phenotypic characterization of the isolated phage included the assessment of phage morphology, host range, stability, and antibiofilm activity. The isolated phage vB_EcoM_ECO78 demonstrated a high lytic activity against MDR E. coli and E. coli serotypes O78: K80: H12 and O26: H11. Additionally, it showed a marked antibiofilm activity and high physical stability at a wide range of temperatures and pH. Genotypic investigations identified a double-stranded DNA genome of 165 912 base pairs (bp) spanning 258 open reading frames (ORFs), out of which 149 ORFs were identified and annotated. In vivo analysis further confirmed the therapeutic potential of vB_EcoM_ECO78 which effectively increased the survival of mice infected with MDR E. coli.

CONCLUSION

The isolated phage vB_EcoM_ECO78 exhibits considerable stability and antibiofilm activity against MDR E. coli isolates, supported by notable environmental fitness and in vivo antibacterial capability.

Designing of immunodiagnostic assay using polyclonal antibodies for detection of Enteropathogenic Escherichia coli strains

Enteropathogenic Escherichia coli (EPEC) is a significant bacterial pathogen that causes infantile diarrhea, particularly in low- and middle-income countries. The lack of a reliable diagnostic method greatly contributes to the increased occurrence and severity of the disease. This study aimed at developing of a cost-effective, rapid, and efficient immunodiagnostic assay for detecting EPEC infection. Lipopolysaccharide (LPS) was extracted from overnight EPEC cultures and combined with alum adjuvant, and then injected into mice for three rounds of immunizations. Subsequently, sera were collected after each immunization and utilized in agglutination assays conducted on glass slides. Both the LPS and colonies of the EPEC isolate used for LPS preparation were employed in these agglutination assays. To evaluate the assay's performance, a total of 34 bacteria, which comprise pathogenic, non-diarrheic E. coli and non-E. coli pathogenic bacteria were used. The developed assay detected EPEC, which yielded positive reactions within 6 minutes on average for both purified LPS and bacterial isolates. The assay exhibited 100% sensitivity and a 95.83% specificity for the detection of EPEC local isolates. Moreover, the assay also detected a low number of bacteria forming units (104X 104 CFU/ml) in spiked fecal samples. This study conclusively confirms that the developed immunodiagnostic assay possesses multiple favorable characteristics, including user-friendliness, high sensitivity, high specificity, cost-effectiveness, and time-efficiency. Hence, this assay can be used as ideal diagnostic assay, which is highly suitable for the detection and screening of EPEC infection in both humans and cattle in one health perspective of resource-limited laboratories.

Intestinal Goblet Cell-Expressed Reg4 Ameliorates Intestinal Inflammation Potentially by Restraining Pathogenic Escherichia coli Infection

An elevated abundance of Escherichia coli (E. coli) has been linked to the onset and progression of inflammatory bowel disease (IBD). Regenerating islet-derived family member 4 (Reg4) has been isolated from patients with ulcerative colitis (UC), but its functions and involved mechanisms in intestinal inflammation are remain incompletely understood. Therefore, we generated an intestinal conditional Reg4 knockout mouse (Reg4ΔIEC) to address this gap by utilizing murine models of enteropathogenic E. coli (EPEC)-infected bowel and dextran sulfate sodium (DSS)-induced colitis. We here demonstrate that REG4 is increased in diseased intestinal mucosa of pediatric IBD, primarily expressed and enriched in intestinal goblet cells. Deficiency of Reg4 in the intestinal epithelium of mice leads to an increase in the Phylum Proteobacteria and in the family Enterobacteriaceae. Administration of recombinant Reg4 protein significantly mitigates EPEC-induced intestinal inflammation and injury in a murine model. In vitro, Reg4 protein suppresses the growth and motility of EPEC, subsequently reducing their adhesion and invasion to the intestinal epithelial cells. Mechanistically, the conserved mannan-binding sites (like C-lectin domain) are essential for Reg4 antimicrobial activity. Moreover, loss of Reg4 in mice increases susceptibility to DSS-induced colitis, which can be improved by gentamicin (GM), an antibiotic for Gram-negative bacteria. In conclusion, intestinal goblet cell-derived Reg4 is crucial for protection against experimental colitis, likely due to its bactericidal activity against EPEC.

Recursive dynamics of GspE through machine learning enabled identification of inhibitors

Type II secretion System has been increasingly recognized as a key driver of virulence in many pathogenic bacteria including Achromobacter xylosoxidans. ATPase GspE is the powerhouse of the T2SS. It powers the entire secretion process by binding with ATP and hydrolyzing it. Therefore, targeting it was thought to have a profound effect on the normal functioning of the whole T2SS. A. xylosoxidans is a Gram-negative bacterium that poses a rising concern to immunocompromised people. It is responsible for many opportunistic infections mostly in people with cystic fibrosis. Due to its intrinsic and acquired resistance mechanisms, it is challenging to treat. In this current study, an extensive machine learning-enabled computational investigation was carried out. Drug libraries were screened using machine learning random forest algorithm trained on non-redundant dataset of 8722 antibacterial compounds with reported IC50 values. Active compounds were then further subjected to molecular docking. To unravel the dynamics and better understand the stability of complexes, the top complexes were subjected to MD Simulations followed by various post-simulation analyses including Trajectory analysis, Atom Contacts, SASA, Hydrogen Bond, RDF, binding free energy calculations, PCA, and AFD analysis. Findings from the study unanimously unveiled Asinex-BAS00263070-28551 as the best inhibitor as it instigated the recursive dynamics of the target by making key hydrogen bond interactions with Walker A motif, suggesting it could serve as the promising drug candidate against GspE. Further experimental in-vivo and in-vitro validation is still required to authenticate the therapeutic effects of these drugs.

The gut microbiota-independent virulence of noninvasive bacterial pathogen Citrobacter rodentium

Attaching and effacing (A/E) bacterial pathogens consist of human pathogens enteropathogenic Escherichia coli, enterohemorrhagic E. coli and their murine equivalent Citrobacter rodentium (CR). Emerging evidence suggests that the complex pathogen-microbiota-host interactions are critical in conferring A/E pathogen infection-induced severe symptoms and lethality in immunocompromised hosts; however, the precise underlying mechanisms remain enigmatic. Here we report that CR infection causes severe colitis and mortality in interleukin 22 knockout (Il22-/-) and Rag1 knockout (Rag1-/-) mice under germ-free (GF) conditions. In a gut microbiota-independent manner, CR colonizes in GF Il22-/- and Rag1-/- animals, triggers colonic epithelial tissue damage and systemic dissemination of CR, and results in lethal infections. Pretreatment with cefoxitin, a broad-spectrum antibiotic, exacerbates CR-induced colitis and lethality in specific-pathogen-free (SPF) Il22-/- and Rag1-/- mice. Together our results reveal that CR possesses a gut microbiota-independent virulence, which is better illustrated during infections in immunocompromised hosts associated with severe outcomes.

Relationships between fecal indicator abundance in water and sand and the presence of pathogenic genes in sand of recreational beaches

For decades, the risk of exposure to infectious diseases in recreational beaches has been evaluated through the quantification of fecal indicator bacteria in water samples using culture methods. The analyses of sand samples have recently been developed as a complement to the monitoring of recreational waters in beach quality assessments. The growing use of molecular techniques for environmental monitoring allows for the rapid detection of pathogenic genes, thus providing more accurate information regarding the health risk of exposure to contaminated sand. The aim of this work was to determine the relationship between the fecal indicators abundance in water and sand and the presence of Shiga toxin-producer Escherichia coli (STEC) in sand by analyzing samples from touristic beaches using culture-dependent (fecal coliforms assay) and culture-independent (real-time PCR of stx1, stx2, and eae genes) techniques. We found a high concentration of coliform bacteria in water and sand in several beaches in eastern Uruguay, with different levels of sanitation networks and levels of urbanization. The presence of STEC virulence genes (mainly stx1) was confirmed in 8 out of 20 sand samples. The recreational use of sandy beaches may imply a risk to the health of its users, especially near streams and creek outflows, thus highlighting the need of monitoring sand bacteriological quality and pathogens using molecular tools.

Phenotypic diversity of type III secretion system activity in enteropathogenic Escherichia coli clinical isolates

Introduction. Enteropathogenic Escherichia coli (EPEC) strains pose a significant threat as a leading cause of severe childhood diarrhoea in developing nations. EPEC pathogenicity relies on the type III secretion system (T3SS) encoded by the locus of enterocyte effacement (LEE), facilitating the secretion and translocation of bacterial effector proteins.Gap Statement. While the regulatory roles of PerC (plasmid-encoded regulator) and GrlA (global regulator of LEE-activator) in ler expression and LEE gene activation are well-documented in the EPEC prototype strain E2348/69, understanding the variability in LEE gene expression control mechanisms among clinical EPEC isolates remains an area requiring further investigation.Aim. This study aims to explore the diversity in LEE gene expression control mechanisms among clinical EPEC isolates through a comparative analysis of secretion profiles under defined growth conditions favouring either PerC- or GrlA-mediated activation of LEE expression.Methodology. We compared T3SS-dependent secretion patterns and promoter expression in both typical EPEC (tEPEC) and atypical EPEC (aEPEC) clinical isolates under growth conditions favouring either PerC- or GrlA-mediated activation of LEE expression. Additionally, we conducted promoter reporter activity assays, quantitative real-time PCR and Western blot experiments to assess gene expression activity.Results. Significant differences in T3SS-dependent secretion were observed among tEPEC and aEPEC strains, independent of LEE sequence variations or T3SS gene functionality. Notably, a clinical tEPEC isolate exhibited increased secretion levels under repressive growth conditions and in the absence of both PerC and GrlA, implicating an alternative mechanism in the activation of Ler (LEE-encoded regulator) expression.Conclusion. Our findings indicate that uncharacterized LEE regulatory mechanisms contribute to phenotypic diversity among clinical EPEC isolates, though their impact on clinical outcomes remains unknown. This challenges the conventional understanding based on reference strains and highlights the need to investigate beyond established models to comprehensively elucidate EPEC pathogenesis.

Antimicrobial Resistance in Diverse Escherichia coli Pathotypes from Nigeria

Escherichia coli is a gram-negative commensal bacterium living in human and animal intestines. Its pathogenic strains lead to high morbidity and mortality, which can adversely affect people by causing urinary tract infections, food poisoning, septic shock, or meningitis. Humans can contract E. coli by eating contaminated food-such as raw or undercooked raw milk, meat products, and fresh produce sold in open markets-as well as by coming into contact with contaminated settings like wastewater, municipal water, soil, and faeces. Some pathogenic strains identified in Nigeria, include Enterohemorrhagic (Verotoxigenic), Enterotoxigenic, Enteropathogenic, Enteroinvasive, and Enteroaggregative E. coli. This causes acute watery or bloody diarrhoea, stomach cramps, and vomiting. Apart from the virulence profile of E. coli, antibiotic resistance mechanisms such as the presence of blaCTX-M found in humans, animals, and environmental isolates are of great importance and require surveillance and monitoring for emerging threats in resource-limited countries. This review is aimed at understanding the underlying mechanisms of evolution and antibiotic resistance in E. coli in Nigeria and highlights the use of improving One Health approaches to combat the problem of emerging infectious diseases.

Bioprospecting of inhibitors of EPEC virulence from metabolites of marine actinobacteria from the Arctic Sea

A considerable number of antibacterial agents are derived from bacterial metabolites. Similarly, numerous known compounds that impede bacterial virulence stem from bacterial metabolites. Enteropathogenic Escherichia coli (EPEC) is a notable human pathogen causing intestinal infections, particularly affecting infant mortality in developing regions. These infections are characterized by microvilli effacement and intestinal epithelial lesions linked with aberrant actin polymerization. This study aimed to identify potential antivirulence compounds for EPEC infections among bacterial metabolites harvested from marine actinobacteria (Kocuria sp. and Rhodococcus spp.) from the Arctic Sea by the application of virulence-based screening assays. Moreover, we demonstrate the suitability of these antivirulence assays to screen actinobacteria extract fractions for the bioassay-guided identification of metabolites. We discovered a compound in the fifth fraction of a Kocuria strain that interferes with EPEC-induced actin polymerization without affecting growth. Furthermore, a growth-inhibiting compound was identified in the fifth fraction of a Rhodococcus strain. Our findings include the bioassay-guided identification, HPLC-MS-based dereplication, and isolation of a large phospholipid and a likely antimicrobial peptide, demonstrating the usefulness of this approach in screening for compounds capable of inhibiting EPEC virulence.

The C-terminal proline-rich repeats of Enteropathogenic E. coli effector EspF are sufficient for the depletion of tight junction membrane proteins and interactions with early and recycling endosomes

BACKGROUND

Enteropathogenic E. coli (EPEC) causes acute infantile diarrhea accounting for significant morbidity and mortality in developing countries. EPEC uses a type three secretion system to translocate more than twenty effectors into the host intestinal cells. At least four of these effectors, namely EspF, Map, EspG1/G2 and NleA, are reported to disrupt the intestinal tight junction barrier. We have reported earlier that the expression of EspF and Map in MDCK cells causes the depletion of the TJ membrane proteins and compromises the integrity of the intestinal barrier. In the present study, we have examined the role of the proline-rich repeats (PRRs) within the C-terminus of EspF in the depletion of the tight junction membrane proteins and identified key endocytosis markers that interact with EspF via these repeats.

RESULTS

We generated mutant EspF proteins which lacked one or more proline-rich repeats (PRRs) from the N-terminus of EspF and examined the effect of their expression on the cellular localization of tight junction membrane proteins. In lysates derived from cells expressing the mutant EspF proteins, we found that the C-terminal PRRs of EspF are sufficient to cause the depletion of TJ membrane proteins. Pull-down assays revealed that the PRRs mediate interactions with the TJ adaptor proteins ZO-1 and ZO-2 as well as with the proteins involved in endocytosis such as caveolin-1, Rab5A and Rab11.

CONCLUSIONS

Our study demonstrates the direct role of the proline-rich repeats of EspF in the depletion of the TJ membrane proteins and a possible involvement of the PRRs in the endocytosis of host proteins. New therapeutic strategies can target these PRR domains to prevent intestinal barrier dysfunction in EPEC infections.

Usefulness and Limitations of PFGE Diagnosis and Nucleotide Sequencing Method in the Analysis of Food Poisoning Pathogens Found in Cooking Employees

In the case of a food poisoning outbreak, it is essential to understand the relationship between cooking workers and food poisoning. Many biological diagnostic methods have recently been developed to detect food poisoning pathogens. Among these diagnostic tools, this study presents PCR-based pulsed-field gel electrophoresis and nucleotide sequencing diagnostic analysis results for diagnosing food poisoning outbreaks associated with cooking employees in Chungcheongnam-do, Republic of Korea. Pulsed-field gel electrophoresis was useful in identifying the food poisoning outbreaks caused by Staphylococcus aureus and Enteropathogenic Escherichia coli. In the case of Norovirus, nucleotide sequencing was used to identify the relationship between cooking workers and the food poisoning outbreak. However, it is difficult to determine whether cooking employees directly caused the food poisoning outbreaks based on these molecular biological diagnostic results alone. A system is needed to integrate epidemiological and diagnostic information to identify a direct correlation between the food poisoning outbreak and cooking employees.

Risk factors and provider awareness of sexually transmitted enteric pathogens among men who have sex with men

Sexual transmission of enteric pathogens among men who have sex with men (MSM) is well documented, although whether providers are cognizant of this risk when MSM patients present with gastrointestinal symptoms has not been studied. Over 34 months at a major tertiary metropolitan medical system, this study retrospectively analyzed 436 BioFire FilmArray Gastrointestinal results from 361 patients documented as MSM. An extensive chart review was performed, including specific sexual behaviors, socioeconomic risk factors, and whether providers charted a sexual history when a patient presented for care. Overall BioFire positivity rate was 62% with no significant difference in positivity between persons living with HIV and those without. Patients charted as sexually active had a significantly increased odds ratio (OR) of a positive result compared to those who were not. Anilingus had the highest OR. Providers charted any type of sexual history in 40.6% of cases, and HIV/infectious disease providers were significantly more likely to do this compared to other subspecialties. Sexual transmission of enteric pathogens within MSM is ongoing, and patients are at risk regardless of living with HIV. Not all sexual behaviors have the same associated risk, highlighting opportunities to decrease transmission. Increased provider vigilance and better patient education on sexual transmission of enteric pathogens are needed to reduce the disease burden.

IMPORTANCE

Our work adds several key findings to the growing body of literature describing the epidemiology of enteric pathogens as sexually transmitted infections among men who have sex with men (MSM). We analyzed clinical test results, housing status, provider awareness, sexual behaviors, and symptoms for 361 patients. We found that any sexual activity was associated with an increased risk of diarrheal pathogen detection, whereas being unhoused was not a risk factor. These findings suggest separate transmission networks between unhoused persons, who are also at risk of infectious diarrhea, and MSM. Moreover, our study suggested low awareness among patient-facing clinicians that diarrheal pathogens can be sexually transmitted. Together, our findings indicate an important opportunity to disrupt transmission cycles by educating clinicians on how to assess and counsel MSM patients.

Systemic inflammation, enteropathogenic E. Coli, and micronutrient insufficiencies in the first trimester as possible predictors of preterm birth in rural Bangladesh: a prospective study

BACKGROUND

An incomplete understanding of preterm birth is especially concerning for low-middle income countries, where preterm birth has poorer prognoses. While systemic proinflammatory processes are a reportedly normal component of gestation, excessive inflammation has been demonstrated as a risk factor for preterm birth. There is minimal research on the impact of excessive maternal inflammation in the first trimester on the risk of preterm birth in low-middle income countries specifically.

METHODS

Pregnant women were enrolled at the rural Bangladesh site of the National Institute of Child Health Global Network Maternal Newborn Health Registry. Serum samples were collected to measure concentrations of the inflammatory markers C-reactive protein (CRP) and Alpha-1-acid glycoprotein (AGP), and stool samples were collected and analyzed for enteropathogens. We examined associations of maternal markers in the first-trimester with preterm birth using logistic regression models. CRP and AGP were primarily modeled with a composite inflammation predictor.

RESULTS

Out of 376 singleton births analyzed, 12.5% were preterm. First trimester inflammation was observed in 58.8% of all births, and was significantly associated with increased odds of preterm birth (adjusted odds ratio [aOR] = 2.23; 95% confidence interval [CI]: 1.03, 5.16), independent of anemia. Maternal vitamin B12 insufficiency (aOR = 3.33; 95% CI: 1.29, 8.21) and maternal anemia (aOR = 2.56; 95% CI: 1.26, 5.17) were also associated with higher odds of preterm birth. Atypical enteropathogenic E. coli detection showed a significant association with elevated AGP levels and was significantly associated with preterm birth (odds ratio [OR] = 2.36; 95% CI: 1.21, 4.57), but not associated with CRP.

CONCLUSIONS

Inflammation, anemia, and vitamin B12 insufficiency in the first trimester were significantly associated with preterm birth in our cohort from rural Bangladesh. Inflammation and anemia were independent predictors of premature birth in this low-middle income setting where inflammation during gestation was widespread. Further research is needed to identify if infections such as enteropathogenic E. coli are a cause of inflammation in the first trimester, and if intervention for infection would decrease preterm birth.

Comparative prevalence of diarrheagenic Escherichia coli between children below five years with close contact to food animals in Kisumu County, Kenya

Introduction

diarrheal infections in young children below five years and food animals are caused by diarrheagenic Escherichia coli strains. The study focused on understanding the association between DEC pathotypes in children below five years and food animals to establish the possibility of zoonotic transmission.

Methods

samples from 150 children who presented with diarrhea at the Kisumu County Hospital and 100 stool samples from food animals were collected and processed using culture methods. Molecular identification of the pathotypes was assayed using a primer-specific polymerase chain reaction that targeted the six virulence genes related to the diarrheagenic Escherichia coli pathotypes.

Results

one hundred and fifty-six study subjects (100 children samples and 56 food animals) samples were positive for E. coli polymerase chain reaction detection revealed a prevalence of (23%) among children below five years and a prevalence of (20%) among the food animals. Children samples showed Enteroaggregative Escherichia coli, having high phenotypic frequency of (12%) followed by Enterotoxigenic Escherichia coli, (5.3%) and Enteropathogenic Escherichia (3.3%) the least being mixed infections Enteroaggregative/Enterotoxigenic Escherichia coli and Enteroaggregative/Enteropathogenic Escherichia coli with (1.3%) respectively. The food animals found in children homesteads were detected to harbor pathogenic strains of E. coli. Enteropathogenic Escherichia coli was the most prevalent pathotypes detected in cattle (13%) followed by Enterotoxigenic Escherichia coli detected in goats at (4%) and poultry at (3%).

Conclusion

presence of diarrheagenic Escherichia coli in food animals could serve as reservoirs of transmitting these bacteria to children below five years.

Hypusination in intestinal epithelial cells protects mice from infectious colitis

Enteropathogenic Escherichia coli (EPEC) is a bacterium that causes attaching/effacing (A/E) lesions and serious diarrheal disease, a major health issue in developing countries. EPEC pathogenicity results from the effect of virulence factors and dysregulation of host responses. Polyamines, including spermidine, play a major role in intestinal homeostasis. Spermidine is the substrate for deoxyhypusine synthase (DHPS), which catalyzes the conjugation of the amino acid hypusine to eukaryotic translation initiation factor 5A (EIF5A); hypusinated EIF5A (EIF5AHyp) binds specific mRNAs and initiates translation. Our aim was to determine the role of hypusination during infection with A/E pathogens. We found that DHPS and EIF5AHyp levels are induced in i) a colonic epithelial cell line and human-derived colon organoids infected with EPEC, and ii) the colon of mice infected with Citrobacter rodentium, the rodent equivalent of EPEC. Specific deletion of Dhps in intestinal epithelial cells worsened clinical, histological, and pro-inflammatory parameters in C. rodentium-infected mice. These animals also exhibited an exacerbated pathogenic transcriptome in their colon. Furthermore, infected mice with specific Dhps deletion exhibited reduced levels of proteins involved in detoxification of tissue-damaging reactive aldehydes and consequently increased electrophile adducts in the colon. Thus, hypusination in intestinal epithelial cells protects from infectious colitis mediated by A/E pathogens.

EspH utilizes phosphoinositide and Rab binding domains to interact with plasma membrane infection sites and Rab GTPases

Enteropathogenic E. coli (EPEC) is a Gram-negative bacterial pathogen that causes persistent diarrhea. Upon attachment to the apical plasma membrane of the intestinal epithelium, the pathogen translocates virulence proteins called effectors into the infected cells. These effectors hijack numerous host processes for the pathogen's benefit. Therefore, studying the mechanisms underlying their action is crucial for a better understanding of the disease. We show that translocated EspH interacts with multiple host Rab GTPases. AlphaFold predictions and site-directed mutagenesis identified glutamic acid and lysine at positions 37 and 41 as Rab interacting residues in EspH. Mutating these sites abolished the ability of EspH to inhibit Akt and mTORC1 signaling, lysosomal exocytosis, and bacterial invasion. Knocking out the endogenous Rab8a gene expression highlighted the involvement of Rab8a in Akt/mTORC1 signaling and lysosomal exocytosis. A phosphoinositide binding domain with a critical tyrosine was identified in EspH. Mutating the tyrosine abolished the localization of EspH at infection sites and its capacity to interact with the Rabs. Our data suggest novel EspH-dependent mechanisms that elicit immune signaling and membrane trafficking during EPEC infection.

Modulating Liquid-Liquid Phase Separation of Nck Adaptor Protein against Enteropathogenic Escherichia coli Infection

Signaling proteins often form biomolecular condensates through liquid-liquid phase separation (LLPS) during intracellular signal transduction. Modulating the LLPS property of intracellular protein condensates will redirect intracellular signals and provide a potential way to regulate cellular physiology. Phosphorylation of multiple tyrosine residues of the transmembrane receptor nephrin is known to drive the LLPS of the adaptor protein Nck and neuronal Wiskott-Aldrich Syndrome protein (N-WASP) and form the Nck signaling complex. Phosphorylation of the translocated intimin receptor (Tir) in the host cell may recruit this enteropathogenic Escherichia coli (EPEC) virulence factor to the Nck signaling complex and lead to the entry of EPEC into the intestine cell. In this work, we first identified a phosphotyrosine (pY)-containing peptide 3pY based on the sequence similarity of nephrin and Tir; 3pY promoted the LLPS of Nck and N-WASP, mimicking the role of phosphorylated nephrin. Next, we designed a covalent blocker of Nck, peptide p1 based on the selected pY peptides, which site-selectively reacted with the SH2 domain of Nck (Nck-SH2) at Lys331 through a proximity-induced reaction. The covalent reaction of p1 with Nck blocked the protein binding site of Nck-SH2 and disintegrated the 3pY/Nck/N-WASP condensates. In the presence of membrane-translocating peptide L17E, p1 entered Caco-2 cells in the cytosol, reduced the number of Nck puncta, and rendered Caco-2 cells resistant to EPEC infection. Site-selective covalent blockage of Nck thereby disintegrates intracellular Nck condensates, inhibits actin reorganization, and shuts down the entrance pathway of EPEC. This work showcases the promotion or inhibition of protein phase separation by synthetic peptides and the use of reactive peptides as LLPS disruptors and signal modulators.

Cross-talk between QseBC and PmrAB two-component systems is crucial for regulation of motility and colistin resistance in Enteropathogenic Escherichia coli

The quorum sensing two-component system (TCS) QseBC has been linked to virulence, motility and metabolism regulation in multiple Gram-negative pathogens, including Enterohaemorrhagic Escherichia coli (EHEC), Uropathogenic E. coli (UPEC) and Salmonella enterica. In EHEC, the sensor histidine kinase (HK) QseC detects the quorum sensing signalling molecule AI-3 and also acts as an adrenergic sensor binding host epinephrine and norepinephrine. Downstream changes in gene expression are mediated by phosphorylation of its cognate response regulator (RR) QseB, and 'cross-talks' with non-cognate regulators KdpE and QseF to activate motility and virulence. In UPEC, cross-talk between QseBC and TCS PmrAB is crucial in the regulation and phosphorylation of QseB RR that acts as a repressor of multiple pathways, including motility. Here, we investigated QseBC regulation of motility in the atypical Enteropathogenic E. coli (EPEC) strain O125ac:H6, causative agent of persistent diarrhoea in children, and its possible cross-talk with the KdpDE and PmrAB TCS. We showed that in EPEC QseB acts as a repressor of genes involved in motility, virulence and stress response, and in absence of QseC HK, QseB is likely activated by the non-cognate PmrB HK, similarly to UPEC. We show that in absence of QseC, phosphorylated QseB activates its own expression, and is responsible for the low motility phenotypes seen in a QseC deletion mutant. Furthermore, we showed that KdpD HK regulates motility in an independent manner to QseBC and through a third unidentified party different to its own response regulator KdpE. We showed that PmrAB has a role in iron adaptation independent to QseBC. Finally, we showed that QseB is the responsible for activation of colistin and polymyxin B resistance genes while PmrA RR acts by preventing QseB activation of these resistance genes.

Effect of xyloglucan associations with gelatin or gelose on Escherichia coli-derived lipopolysaccharide-induced enteritis in rats

Background

Escherichia coli is the predominant non-pathogenic facultative microbe of the human intestine, although some strains are diarrhoeagenic in humans. E. coli-derived lipopolysaccharide (LPS) induces diarrhoea, intestinal barrier impairment, bacterial translocation and intestinal inflammation. Associations with the mucoprotectant xyloglucan exhibit antidiarrhoeal effects. This study evaluated and compared the effects of xyloglucan in combination with gelatin or gelose (agar-agar) on jejunal permeability and inflammation using an in vivo rat model of E. coli LPS-induced enteritis.

Methods

Xyloglucan (12.5 mg/kg) plus gelatin (250 mg/kg) or gelose (250 or 500 mg/kg) were administered orally 2 hours before intraperitoneal injection with E. coli LPS. Following euthanasia, jejunal segments were removed for intestinal permeability measurement in Ussing chambers and inflammatory tone evaluation by myeloperoxidase activity assay.

Results

LPS administration increased jejunal permeability and increased mucosal inflammation in male Wistar rats. Xyloglucan plus gelatin 250 mg/kg and xyloglucan plus gelose 500 mg/kg significantly attenuated LPS-induced jejunal hyperpermeability and myeloperoxidase activity.

Conclusion

Xyloglucan, a known mucosal barrier protector, in combination with gelatin or gelose, has beneficial and comparable effects on intestinal permeability and inflammation following E. coli LPS insult in male rats.

Domestic cats are potential reservoirs of multidrug-resistant human enteropathogenic E. coli strains in Bangladesh

Companion animals serve as our best friends, confidants, and family members. Thus, disease and antibiotic resistance gene transmission in pets and humans must be sought out. The study aimed to identify the common pathogenic Escherichia coli (E.coli) in pet cats and the antibiotic resistance patterns and resistant gene distribution. Samples (n = 210) were collected from different veterinary clinics in Bangladesh's cities of Mymensingh and Dhaka. Pathogenic E. coli was identified using conventional and molecular approaches. The disc diffusion method assessed the resistance profile against 12 antibiotics, and PCR was used to identify the beta-lactam resistance genes. The prevalence of the stx-1 gene was found to be 2.86%, whereas the rfbO157 prevalence was found to be 1.90% in cats. The stx-1 gene (n = 6) was 100% resistant to erythromycin and imipenem, whereas 100% sensitive to chloramphenicol. In turn, the rfbO157 gene (n = 4) exhibited 100% resistance to erythromycin, imipenem, cefixime, and azithromycin. In addtion, we identified genes that exhibit resistance to beta-lactam antibiotics (100% blaTEM, 40% blaCTX-M, 40% blaSHV2). This study found shiga-toxin producing and extended-spectrum beta-lactamase (ESBL) producing E. coli for the first time in pet cats of Bangladesh. Furthermore, the antimicrobial resistance (AMR) profile of the isolated strains refers to the occurrence of multidrug, which concerns cats and their owners. The existence of these genes in non-diarrheic pet animal isolates indicates that domestic pets may serve as a reservoir for human infection. Thus, one health strategy comprising animal and human health sectors, governments, together with stakeholders is needed to confront multidrug-resistant E. coli infections in Bangladesh.

Topology and function of translocated EspZ

EspZ and Tir are essential virulence effectors of enteropathogenic Escherichia coli (EPEC). EspZ, the second translocated effector, has been suggested to antagonize host cell death induced by the first translocated effector, Tir (translocated intimin receptor). Another characteristic of EspZ is its localization to host mitochondria. However, studies that explored the mitochondrial localization of EspZ have examined the ectopically expressed effector and not the more physiologically relevant translocated effector. Here, we confirmed the membrane topology of translocated EspZ at infection sites and the involvement of Tir in confining its localization to these sites. Unlike the ectopically expressed EspZ, the translocated EspZ did not colocalize with mitochondrial markers. Moreover, no correlation has been found between the capacity of ectopically expressed EspZ to target mitochondria and the ability of translocated EspZ to protect against cell death. Translocated EspZ may have to some extent diminished F-actin pedestal formation induced by Tir but has a marked effect on protecting against host cell death and on promoting host colonization by the bacteria. Taken together, our results suggest that EspZ plays an essential role in facilitating bacterial colonization, likely by antagonizing cell death mediated by Tir at the onset of bacterial infection. This activity of EspZ, which occurs by targeting host membrane components at infection sites, and not mitochondria, may contribute to successful bacterial colonization of the infected intestine. IMPORTANCE EPEC is an important human pathogen that causes acute infantile diarrhea. EspZ is an essential virulence effector protein translocated from the bacterium into the host cells. Detailed knowledge of its mechanisms of action is, therefore, critical for better understanding the EPEC disease. We show that Tir, the first translocated effector, confines the localization of EspZ, the second translocated effector, to infection sites. This activity is important for antagonizing the pro-cell death activity conferred by Tir. Moreover, we show that translocated EspZ leads to effective bacterial colonization of the host. Hence, our data suggest that translocated EspZ is essential because it confers host cell survival to allow bacterial colonization at an early stage of bacterial infection. It performs these activities by targeting host membrane components at infection sites. Identifying these targets is critical for elucidating the molecular mechanism underlying the EspZ activity and the EPEC disease.

Thermal Adaptation Alters Response to Thermal Stress and Expression of Virulent Genes (eae, stx1, stx2, and hlyA) in Pathogenic Escherichia coli Isolated from Pork

Escherichia coli encounter variety of environmental and processing stresses during their growth, survival, and infection. Herein, the thermotolerance behavior and transcription of virulent genes responsible for the pathogenicity in isolated strains of pathogenic E. coli were evaluated. Among 176 E. coli isolates, 4 isolates (2.27%) were confirmed to be pathogenic E. coli, out of which 2 isolates were positive for EHEC and 2 were positive for EPEC based on their virulence factors. Thermotolerance was induced under thermal adaptation at higher temperature, regardless of the pathotypes. Cells grown and adapted at 42 °C, exhibited highest transcription of genes associated with adhesion (eae), hemolysis (hlyA), and shiga toxin production (stx1). However, expression of these genes was downregulated in cells adapted at lower temperature of 4 °C and 25 °C compared to control. Further, transcription of stx2 was upregulated by 70% and 17% at 4 °C and 25 °C, respectively, while the transcription level was reduced by 44% relative to control at 42 °C. The findings indicate that expression of virulent genes in pathogenic E. coli at elevated temperature do not be depend on thermotolerance of the strain harboring these genes.

Molecular Prevalence of Diarrheal Pathogens in Children with Acute Diarrhea in Southeastern Gabon

Diarrheal diseases are a major cause of morbidity and mortality in infants and young children, particularly in sub-Saharan countries. In Gabon, there are few data on the prevalence of diarrheal pathogens in children. The aim of this study was to assess the prevalence of diarrheal pathogens in children with diarrhea in southeastern Gabon. Stool samples (n = 284) from Gabonese children 0 to 15 years of age with acute diarrhea were analyzed using polymerase chain reaction targeting 17 diarrheal pathogens. At least one pathogen was detected in 75.7% of samples (n = 215). Coinfection with multiple pathogens was observed in 44.7% of patients (n = 127). Diarrheagenic Escherichia coli was the most commonly detected pathogen (30.6%, n = 87), followed by adenovirus (26.4%, n = 75), rotavirus (16.9%, n = 48), Shigella sp. (16.5%, n = 47), Giardia duodenalis (14.4%, n = 41), norovirus GII (7.0%, n = 20), sapovirus (5.6%, n = 16), Salmonella enterica (4.9%, n = 14), astrovirus (4.6%, n = 13), Campylobacter jejuni/coli (4.6%, n = 13), bocavirus (2.8%, n = 8), and norovirus GI (2.8%, n = 8). Our study provides useful information on the possible causes of diarrheal diseases affecting children in southeastern Gabon. A similar study with a control group of healthy children is needed to assess the burden of the disease attributed to each pathogen.

Bacterial resistance to commonly prescribed antibiotics was rare among children hospitalised for clinical dysentery

AIM

Temporal changes in common pathogens that cause clinical dysentery have been described in Europe. We aimed to describe the distribution of pathogens and their antibiotic resistance in hospitalised Israeli children.

METHODS

This study retrospectively studied children hospitalised for clinical dysentery, with or without a positive stool culture, from 1 January 2016 to 31 December 2019.

RESULTS

We diagnosed 137 patients (65% males), with clinical dysentery at a median age of 3.7 (interquartile range 1.5-8.2) years. Stools were cultured in 135 patients (99%), and the results were positive in 101 (76%). These comprised Campylobacter (44%), Shigella sonnei (27%), non-typhoid Salmonella (18%) and enteropathogenic Escherichia coli (12%). Only one of the 44 Campylobacter cultures was resistant to erythromycin and one of the 12 enteropathogenic Escherichia coli cultures was resistant to ceftriaxone. None of the Salmonella and Shigella cultures were resistant to ceftriaxone or erythromycin. We did not find any pathogens that were associated with a typical clinical presentation or laboratory results on admission.

CONCLUSION

The most common pathogen was Campylobacter, in line with recent European trends. Bacterial resistance for commonly prescribed antibiotics was rare, and these findings support the current European recommendations.

High Burden of Co-Infection with Multiple Enteric Pathogens in Children Suffering with Diarrhoea from Rural and Peri-Urban Communities in South Africa

Infectious diarrhoea contributes to high morbidity and mortality in young children from sub-Saharan Africa. The aim of this study was to assess the prevalence of single and multiple diarrhoeal-causing pathogen combinations in children suffering from diarrhoea from rural and peri-urban communities in South Africa. A total of 275 diarrhoea stool specimens were collected between 2014 and 2016 from Hospitals and Primary Health Care clinics. The BioFire^® FilmArray^® Gastrointestinal panel was used to simultaneously detect 22 diarrhoea pathogens (viruses, bacteria, parasites) known to cause diarrhoea. A total of 82% (226/275) enteric pathogens were detected in the stool specimens. The two most detected bacterial, viral and parasitic pathogens each included: EAEC (42%), EPEC (32%), Adenovirus F40/41 (19%), Norovirus (15%), Giardia (8%) and Cryptosporidium (6%), respectively. Single enteric pathogen infections were recorded in 24% (65/275) specimens with EAEC, and Norovirus was found in 26% (17/65) and 14% (9/65) of the specimens, respectively. Multiple enteric pathogen combinations were recorded in 59% (161/275) of the stool specimens with 53% (85/161) containing two pathogens, 22% (35/161) containing three pathogens and 25% (41/161) containing four or more pathogens. The results from this study demonstrated the complex nature of pathogen co-infections in diarrhoeal episodes which could have an impact on treatment effectiveness.

Population genomic analysis reveals the emergence of high-risk carbapenem-resistant Escherichia coli among ICU patients in China

OBJECTIVES

The increasing incidence of carbapenem-resistant Enterobacterales (CRE) mediated nosocomial infections has caused a significant public health burden globally. Currently, the prevalence and genomic characteristics of carbapenem-resistant Escherichia coli (CREC) in patients admitted to the intensive care unit (ICU) are unknown.

METHODS

Herein, we present a nationwide genomic investigation of CREC isolates among ICU patients in China in 2018 and 2020. In total, 113 CREC isolates were identified from 1105 samples in 25 hospitals, and investigated with phenotyping and genomics approaches.

RESULTS

Carbapenemases were produced in 94.69% (107/113) of CREC isolates, which comprise KPC-2 (n = 53, 49.53%), NDM (n = 51, 47.66%), IMP-4 (n = 2, 1.87%), and OXA-181 (n = 1, 0.93%). Notably, CREC isolates co-carrying mcr-9 and bla_NDM-5 or tet(X4) and bla_NDM-5 were first identified in clinical settings. The carbapenemase genes of most isolates were located on the plasmids. The bla_KPC gene was mainly mediated by IncFII plasmids (n = 37, 69.81%), and bla_NDM was located on the IncX3 plasmid (n = 36, 70.59%). CREC isolates belonged to diverse sequence types (STs) of which ST131 was the most prevalent bla_KPC-positive CREC isolates (34/113, 30.09%), while bla_NDM was associated with ST617 and ST410 isolates, thereby indicating that multiple CREC clones spread in Chinese ICU patients.

CONCLUSIONS

This study highlights the emerging threat of high-risk CREC isolates such as ST131 circulating in the ICU in China. Hence, stringent monitoring of such high-risk clones should be performed.

Biological pathways via which the anthocyanin malvidin alleviated the murine colitis induced by Citrobacter rodentium

Enteropathogenic E. coli (EPEC) is a causal agent for diarrheal diseases and contributes to morbidity and mortality in children under the age of five years. The emergence and rapid spread of antibiotic resistant EPEC strains necessitate the search for novel alternatives to antibiotics. In this study, we used Citrobacter rodentium, a natural mouse pathogen that mimics many aspects of human EPEC infections, to investigate the antimicrobial properties of the blueberry anthocyanin malvidin 3-glucoside (MG) using a multi-omics approach. MG supplementation reversed the bodyweight loss induced by C. rodentium infection and improved colonic hyperplasia and histopathological scores. In the colon tissue, MG supplementation significantly increased the expression of Hace1, a key regulator of TNFα-driven signaling, and impacted multiple pathways, such as TGFβ signaling. MG partially restored C. rodentium-induced microbial dysbiosis and significantly enhanced the abundance of the probiotic Bifidobacterium animalis. Moreover, MG disrupted the interactions of E. coli with other gut microbes. MG significantly mediated several host- and microbiota-derived metabolites, such as cytosine, ureidopropionic acid, and glutaric acid. MG normalized the bioactive lipid oleoylethanolamine, a member of the endocannabinoid system, from the dysregulated level in infected mice, directly contributing to its overall beneficial effects. Our findings provided novel insights into molecular processes via which the flavonoid malvidin exerts its biological effects in the gastrointestinal tract.

Pathophysiology of Enteropathogenic Escherichia coli-induced Diarrhea

Enteropathogenic Escherichia coli (EPEC) are important diarrheal pathogens of infants and young children. Since the availability of molecular diagnosis methods, we now have new insights into the incidence and prevalence of these infections. Recent epidemiological studies indicate that atypical EPEC (aEPEC) are seen more frequently than typical EPEC (tEPEC) worldwide, including in both endemic diarrhea and diarrhea outbreaks. Therefore, it is important to further characterize the pathogenicity of these emerging strains. The virulence mechanisms and pathophysiology of the attaching and effacing lesion (A/E) and the type-three-secretion-system (T3SS) are complex but well-studied. A/E strains use their pool of locus of enterocyte effacement (LEE)-encoded and non-LEE-encoded effector proteins to subvert and modulate cellular and barrier properties of the host. However, the exact mechanisms of diarrhea in EPEC infection are not completely understood. From the clinical perspective, there is a need for fast, easy, and inexpensive diagnostic methods to define optimal treatment and prevention for children in endemic areas. In this article, we present a review of the classification of EPEC, epidemiology, pathogenesis of the disease caused by these bacteria, determinants of virulence, alterations in signaling, determinants of colonization vs. those of disease, and the limited information we have on the pathophysiology of EPEC-induced diarrhea. This article combines peer-reviewed evidence from our own studies and the results of an extensive literature search in the databases PubMed, EMBASE, and Scopus.

High variation across E. coli hybrid isolates identified in metabolism-related biological pathways co-expressed with virulent genes

Virulent genes present in Escherichia coli (E. coli) can cause significant human diseases. These enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC) isolates with virulent genes show different expression levels when grown under diverse laboratory conditions. In this research, we have performed differential gene expression analysis using publicly available RNA-seq data on three pathogenic E. coli hybrid isolates in an attempt to characterize the variation in gene interactions that are altered by the presence or absence of virulent factors within the genome. Almost 26.7% of the common genes across these strains were found to be differentially expressed. Out of the 88 differentially expressed genes with virulent factors identified from PATRIC, nine were common in all these strains. A combination of Weighted Gene Co-Expression Network Analysis and Gene Ontology Enrichment Analysis reveals significant differences in gene co-expression involving virulent genes common among the three investigated strains. The co-expression pattern is observed to be especially variable among biological pathways involving metabolism-related genes. This suggests a potential difference in resource allocation or energy generation across the three isolates based on genomic variation.

Straightforward Synthesis of the Pentasaccharide Repeating Unit of the O-Antigenic Polysaccharide from the Enteropathogenic Escherichia coli O142

The pentasaccharide repeating unit rich in 2-acetamido sugars corresponding to the O-antigenic polysaccharide from enteropathogenic Escherichia coli (E. coli) has been synthesized as the p-methoxyphenyl glycoside in excellent yield using a sequential glycosylation strategy. Regioselective glycosylation, use of a single monosaccharide intermediate in multiple glycosylations, and use of thioglycosides as glycosyl donors in the presence of a combination of N-iodosuccinimide (NIS) and perchloric acid supported over silica (HClO4–SiO2) are key components of the synthetic strategy. All glycosylation reactions were high-yielding with excellent stereochemical outcome.

Catalytic nanomedicine: a brief review of bionanocatalysts

Catalytic nanomedicine is a research area and source of disruptive technology that studies the application of bionanocatalysts (organically functionalized mesoporous nanostructured materials with catalytic properties) in diverse areas such as disinfection, tissue regeneration in chronic wounds and oncology. This paper reviews the emergence of catalytic nanomedicine in 2006, its basic principles, main achievements and future perspectives, as well as giving a summary of the knowledge gaps that need to be addressed to exploit the full potential of this novel discipline. This review intends to foster knowledge dissemination regarding catalytic nanomedicine, and to encourage further research to elucidate the mechanisms and possible applications of these nanomaterials.

Factors Determining Effective Probiotic Activity: Evaluation of Survival and Antibacterial Activity of Selected Probiotic Products Using an "In Vitro" Study

There are many different probiotic products on the market. Are they all equally effective? What criteria should a probiotic formulation meet to provide the most benefit to the patient? The current research aims to evaluate the parameters that influence the effectiveness of market probiotic products. These properties are critical for restoring eubiosis in patients with drug-induced dysbiosis or other pathological conditions, which could be caused by stress, wrong eating. Methods: The disintegration time of probiotic capsules in hydrochloric acid was investigated using a disintegration testing device. The survival rate of probiotic preparations in hydrochloric acid at pH 2 and in a 0.4% bile solution was then evaluated. For this purpose, the number of bacteria before and after incubation in the respective solutions was determined using the plate method. Inhibition of gastrointestinal pathogens by the probiotic products was determined using the Strus bar graph method. The highest survival rate of probiotic bacteria at low pH is shown by preparations produced in the form of acid-resistant capsules. Conclusions: The most important factor determining the good survival of bacterial strains under conditions simulating the gastrointestinal tract is the type of capsule used for their production and storage. The best antimicrobial activity against most common human gastrointestinal pathogens such as Eschericha coli, Shigella, Salmonella spp., Clostridioides difficile (the largest inhibition zones) are shown by probiotic products with the greatest diversity of bacterial strains.

Detection of Foodborne Pathogens in Acute Gastroenteritis Patient’s Stool Samples Using the BioFire® FilmArray® Gastrointestinal PCR Panel in the Republic of Trinidad and Tobago, West Indies

In 2009, the burden of illness study for acute gastroenteritis in Trinidad and Tobago highlighted that ~10% of stool samples tested were positive for a foodborne pathogen. The study also noted that limited laboratory screening for pathogens contributed to a lack of etiology as public health hospitals only routinely tested for Salmonella and Shigella, and sometimes for Escherichia coli and Campylobacter. To better understand the foodborne pathogens responsible for acute gastroenteritis, enhanced testing using the BioFire® FilmArray® Gastrointestinal PCR panel was used to screen diarrheal stool samples for 22 pathogens from patients in 2018. The five general public health hospitals (San Fernando, Mt. Hope, Port of Spain, Sangre Grande, and Tobago) were notified of research activities and diarrheal stool samples were collected from all acute gastroenteritis patients. A total of 66 stools were screened and ~30% of samples tested positive for a foodborne pathogen. The current study showed that a much wider range of enteric pathogens were associated with acute gastroenteritis in Trinidad and Tobago than previously reported in 2009. These findings can be used by health officials to guide appropriate interventions, as well as to provide evidence for adoption of the PCR panel detection method at public health hospitals to benefit patient care.

Molecular characterization of diarrheagenic Escherichia coli isolates from children with diarrhea: A cross-sectional study in four provinces of Mozambique: Diarrheagenic Escherichia coli in Mozambique

OBJECTIVES

Analyze the frequency of diarrheagenic Escherichia coli (DEC) pathotypes and their antimicrobial resistance profiles among children aged <15 years with diarrhea in four Mozambican provinces.

METHODS

A cross-sectional hospital-based surveillance program of diarrhea was implemented in Maputo, Sofala, Zambézia, and Nampula. A single stool sample was collected from each child from May 2014 to May 2017. Culture methods and biochemical characterization were performed to detect E. coli strains. DEC pathotypes were determined by conventional polymerase chain reaction targeting specific virulence genes. Antimicrobial susceptibility was assessed by the Kirby-Bauer method.

RESULTS

From 723 specimens analyzed by culture, 262 were positive for E. coli. A total of 208 samples were tested by polymerase chain reaction for DEC identification, of which 101 (48.6%) were positive for a DEC pathotype. The predominant pathotypes were enteroaggregative (66.3%, 67/101), enteropathogenic (15.8%, 16/101), enterotoxigenic (13.9%, 14/101), and enteroinvasive E. coli (4.0%, 4/101). No Shiga toxin-producing E. coli was identified. Regardless of the province, the most frequent pathotype was enteroaggregative E. coli. Isolated DEC presented high frequency of resistance to ampicillin (97.8%), tetracycline (68.3%), chloramphenicol (28.4%), nalidixic acid (19.5%), and gentamicin (14.4%).

CONCLUSION

Children with diarrhea in Mozambique had DEC and higher resistance to ampicillin and tetracycline.

Gold nanoparticles (AuNP)-based aptasensor for enteropathogenic Escherichia coli detection

BACKGROUND

Diarrhea is a major cause of severe gastrointestinal illness in the infant especially in many developing countries. Although this molecular technique has been accepted as standard technique to detect Diarrhea-causing EPEC, the practical aspect of this technique for in-site rapid screening purposes is still facing a major challenge. In this study, we characterized EPEC specific aptamers and applied it as an AuNP-based aptasensor for point of care (POC) diagnosis purpose.

METHODS

As many as six selected DNA aptamers was screened using target bacteria and the bound aptamer was measured by qPCR technique. Moreover, Kd value for each optimal bound aptamer was measured by using the same technique. Colorimetry assay was applied to test specificity and LOD of AuNP-based aptasensor.

RESULTS

Two DNA aptamers have been successfully obtained to detect Enteropathogenic Escherichia coli K.1.1. DNA aptamer S8-7 exhibited constant dissociation (Kd) value of 17.08 nM, while DNA aptamer S10-5 exhibited Kd value of 34.14 nM. AuNP-based aptasensor showed high selectivity and specificity for EPEC K.1.1 with a limit of detection (LOD) value of 10⁵ CFU/mL. Truncation study on DNA aptamer S8-7 showed that elimination of primer binding sequence only slightly increased both performance of detection and LOD value of AuNP-based aptasensor.

CONCLUSION

Further study is necessary to improve AuNP-aptasensor performance such as through mutagenesis approach on targeted DNA aptamers before AuNP-based aptasensor can be applied as a biosensor in point of care (POC) diagnosis.

Enteropathogenic Escherichia coli (EPEC) expressing a non-functional bundle-forming pili (BFP) also leads to increased growth failure and intestinal inflammation in C57BL/6 mice

Bundle-forming pili (BFP) are implicated in the virulence of typical enteropathogenic E. coli (EPEC), resulting in enhanced colonization and mild to severe disease outcomes; hence, non-functional BFP may have a major influence on disease outcomes in vivo. Weaned antibiotic pre-treated C57BL/6 mice were orally infected with EPEC strain UMD901 (E2348/69 bfpA C129S); mice were monitored daily for body weight; stool specimens were collected daily; and intestinal tissues were collected at the termination of the experiment on day 3 post-infection. Real-time PCR was used to quantify fecal shedding and tissue burden. Intestinal inflammatory biomarkers lipocalin-2 (LCN-2) and myeloperoxidase (MPO) were also assessed. Infection caused substantial body weight loss, bloody diarrhea, and intestinal colonization with fecal and intestinal tissue inflammatory biomarkers that were comparable to those previously published with the wild-type typical EPEC strain. Here we further report on the evaluation of an EPEC infection model, showing how disruption of bfp function does not impair, and may even worsen diarrhea, colonization, and intestinal disruption and inflammation. More research is needed to understand the role of bfp in pathogenicity of EPEC infections in vivo.

Regulated necrosis, a proinflammatory cell death, potentially counteracts pathogenic infections

Since the discovery of cell apoptosis, other gene-regulated cell deaths are gradually appreciated, including pyroptosis, ferroptosis, and necroptosis. Necroptosis is, so far, one of the best-characterized regulated necrosis. In response to diverse stimuli (death receptor or toll-like receptor stimulation, pathogenic infection, or other factors), necroptosis is initiated and precisely regulated by the receptor-interacting protein kinase 3 (RIPK3) with the involvement of its partners (RIPK1, TRIF, DAI, or others), ultimately leading to the activation of its downstream substrate, mixed lineage kinase domain-like (MLKL). Necroptosis plays a significant role in the host's defense against pathogenic infections. Although much has been recognized regarding modulatory mechanisms of necroptosis during pathogenic infection, the exact role of necroptosis at different stages of infectious diseases is still being unveiled, e.g., how and when pathogens utilize or evade necroptosis to facilitate their invasion and how hosts manipulate necroptosis to counteract these detrimental effects brought by pathogenic infections and further eliminate the encroaching pathogens. In this review, we summarize and discuss the recent progress in the role of necroptosis during a series of viral, bacterial, and parasitic infections with zoonotic potentials, aiming to provide references and directions for the prevention and control of infectious diseases of both human and animals.

Infection With Escherichia Coli Pathotypes Is Associated With Biomarkers of Gut Enteropathy and Nutritional Status Among Malnourished Children in Bangladesh

Escherichia coli (E. coli) pathotypes are the most common cause of diarrhea, especially in developing countries. Environmental Enteric Dysfunction (EED) is presumed to be the result of infection with one or more pathotypes and can affect intestinal health and childhood growth. We sought to investigate the association of E. coli pathotypes infection with biomarkers of EED and nutritional status among slum-dwelling malnourished children in Bangladesh. This study comprised a total of 1050 stunted and at risk of stunting children. TaqMan Array Card assays were used to determine the presence of E. coli pathotypes in feces. Prevalence of infection with EAEC was highest (68.8%) in this cohort of children, followed by EPEC (55.9%), ETEC (44%), Shigella/EIEC (19.4%) and STEC (3.2%). The levels of myeloperoxidase and calprotectin were significantly higher in EAEC (P=0.02 and P=0.04), EPEC (P=0.02 and P=0.03) and Shigella/EIEC (P=0.05 and P=0.02) positive participants while, only calprotectin was significantly higher in ETEC (P=0.01) positive participants. Reg1B was significantly higher in participants with EAEC (P=0.004) while, neopterin levels were significantly lower in ETEC (P=0.003) and Shigella/EIEC (P=0.003) positive cases. A significant positive relationship was observed between EAEC and fecal levels of Reg1B (β = 0.28; 95% CI = 0.12, 0.43; p-value<0.001). Besides, ETEC was found to be positively and significantly associated with the levels of calprotectin (β = 0.14; 95 percent CI = 0.01, 0.26; p-value=0.037) and negatively with neopterin (β = -0.16; 95% CI = -0.30, -0.02; p-value=0.021). On the other hand, infection with EPEC was found to be negatively associated with length-for-age (β = -0.12; 95% CI = -0.22, -0.03; p-value=0.011) and weight-for-age (β = -0.11; 95% CI = -0.22, -0.01; p-value=0.037). The study findings suggest that infection with certain E. coli pathotypes (EAEC and ETEC) influences gut health and EPEC is associated with linear growth and underweight in Bangladeshi children.

Genomic Diversity, Virulence Gene, and Prophage Arrays of Bovine and Human Shiga Toxigenic and Enteropathogenic Escherichia coli Strains Isolated in Hungary

Escherichia coli belonging to the enterohemorrhagic (EHEC), Shiga toxin-producing (STEC) and atypical enteropathogenic (aEPEC) pathotypes are significant foodborne zoonotic pathogens posing serious health risks, with healthy cattle as their main reservoir. A representative sampling of Hungarian cattle farms during 2017-2018 yielded a prevalence of 6.5 and 5.8% for STEC and aEPEC out of 309 samples. The draft genomes of twelve STEC (of them 9 EHEC) and four aEPEC of bovine origin were determined. For comparative purposes, we also included 3 EHEC and 2 aEPEC strains of human origin, as well four commensal isolates and one extraintestinal pathogenic E. coli (ExPEC) obtained from animals in a final set of 26 strains for a WGS-based analysis. Apart from key virulence genes, these isolates harbored several additional virulence genes with arrays characteristic for the site of isolation. The most frequent insertion site of Shiga toxin (stx) encoding prophages was yehV for the Stx1 prophage and wrbA and sbcB for Stx2. For O157:H7 strains, the locus of enterocyte effacement pathogenicity island was present at the selC site, with integration at pheV for other serotypes, and pheU in the case of O26:H11 strains. Several LEE-negative STEC and aEPEC as well as commensal isolates carried additional prophages, with an average of ten prophage regions per isolate. Comparative phylogenomic analysis showed no clear separation between bovine and human lineages among the isolates characterized in the current study. Similarities in virulence gene arrays and close phylogenetic relations of bovine and human isolates underline the zoonotic potential of bovine aEPEC and STEC and emphasize the need for frequent monitoring of these pathogens in livestock.

Phage display of environmental protein toxins and virulence factors reveals the prevalence, persistence, and genetics of antibody responses

Microbial exposures are crucial environmental factors that impact healthspan by sculpting the immune system and microbiota. Antibody profiling via Phage ImmunoPrecipitation Sequencing (PhIP-Seq) provides a high-throughput, cost-effective approach for detecting exposure and response to microbial protein products. We designed and constructed a library of 95,601 56-amino acid peptide tiles spanning 14,430 proteins with "toxin" or "virulence factor" keyword annotations. We used PhIP-Seq to profile the antibodies of ∼1,000 individuals against this "ToxScan" library. In addition to enumerating immunodominant antibody epitopes, we studied the age-dependent stability of the ToxScan profile and used a genome-wide association study to find that the MHC-II locus modulates bacterial epitope selection. We detected previously described anti-flagellin antibody responses in a Crohn's disease cohort and identified an association between anti-flagellin antibodies and juvenile dermatomyositis. PhIP-Seq with the ToxScan library is thus an effective tool for studying the environmental determinants of health and disease at cohort scale.

Genetic characterization and antimicrobial susceptibility of Escherichia coli isolated from household water sources in northern Ghana

The microbial quality of household water is an important issue in developing countries, especially in Ghana, where many people still depend on unimproved sources of water. The present study investigated the prevalence, genetic characteristics, and antimicrobial resistance profile of Escherichia coli from surface water sources. Fifty-two water samples were analyzed by using a spread plate, a biochemical test, and multiplex polymerase chain reactions. E. coli was isolated from each of the 52 water samples. Of these isolates, 75% were noted to possess virulence genes. Approximately 54% of the isolates were characterized as follows: enterotoxigenic E. coli (ETEC, 10.26%), enteropathogenic E. coli (EPEC, 17.95%), verotoxigenic E. coli (VTEC, 23.07%), and enteroinvasive E. coli (EIEC, 2.57%). Eighteen of the fifty-two isolates could not be characterized due to heterogeneity in banding. The disc diffusion method was used to test for antimicrobial susceptibility. The isolates were most resistant to ceftazidime, augmentin, and cefuroxime. Multidrug resistance was recorded in 48.1% of the isolates. In contrast, the isolates were most susceptible to ciprofloxacin (86.5%), nitrofurantoin (84.6%), and ofloxacin (75%). These results revealed a high diversity and widespread of E. coli in northern Ghana. The study provides important data for public health nationwide surveillance of E. coli in surface water across the country.

Food animals as reservoirs and potential sources of multidrug-resistant diarrheagenic E. coli pathotypes: Focus on intensive pig farming in South Africa

Background

Diarrheagenic E. coli (DEC) strains are a major cause of diarrheal diseases in both developed and developing countries. Healthy asymptomatic animals may be reservoirs of zoonotic DEC, which may enter the food chain via the weak points in hygiene practices.

Aim

We investigated the prevalence of DEC along the pig production continuum from farm-to-fork.

Methods

A total of 417 samples were collected from specific points along the pig production system, that is, farm, transport, abattoir and food. E. coli was isolated and enumerated using Colilert. Ten isolates from each Quanti-tray were selected randomly and phenotypically identified using eosin methylene blue agar selective media. Real-time polymerase chain reaction (PCR) was used to confirm the species and to classify them into the various diarrheagenic pathotypes. Antimicrobial susceptibility was determined against a panel of 20 antibiotics using the Kirby-Bauer disk diffusion method and EUCAST guideline.

Results

The final sample size consisted of 1044 isolates, of which 45.40% (474/1044) were DEC and 73% (762/1044) were multidrug-resistant. Enteroinvasive E. coli (EIEC) was the most predominant DEC at all the sampling sites.

Conclusion

The presence of DEC in food animal production environments and food of animal origin could serve as reservoirs for transmitting these bacteria to humans, especially in occupationally exposed workers and via food. Adherence to good hygienic practices along the pig production continuum is essential for mitigating the risk of transmission and infection, and ensuring food safety.