Search Results (117)

Avian pathogenic Escherichia coli (APEC) is highly infective in poultry, causing significant economic losses to the poultry industry. As an extraintestinal pathogenic strain, adherence is a critical step in the infection. The functions of several adhesins, including type I, P, and Curli fimbriae, have been extensively studied. However, the roles of other adhesins, like Sfm, remain largely unexplored. Sfm is widely present in E. coli. Although the Sfm cluster is an ortholog of the fim gene cluster of Salmonella type I fimbriae, the biological function of Sfm in APEC has not yet been elucidated. To investigate whether Sfm in APEC CE129 plays a role in virulence, in this study, we constructed recombinant strains by expressing Sfm in the fimbriae-deficient strain SE5000. Additionally, a CE129 sfmA mutant strain was constructed. The resulting changes in adherence, biofilm formation, resistance to macrophage phagocytosis, and resistance to serum bactericidal ability were observed. The adherence ability of CE129ΔsfmA was reduced by 41%. HD-11 cells demonstrated a 30% increase in the phagocytosis of CE129ΔsfmA, and a 50% reduction in SE5000 (pBR322-sfm). The sfm deletion mutant showed a 23.9% reduction in the resistance to serum bactericidal ability, while SE5000 (pBR322-sfm) displayed a 32% increase. SE5000 (pBR322-sfm) exhibited a 34% increase in biofilm formation, and CE129ΔsfmA demonstrated a 21% decrease. Real-time PCR was employed to examine the impact of Sfm deletion on the transcription level of key virulence factors (fimA, fliC, papC, tsh, ompA, and iss). The results indicated that Sfm in CE129 is closely associated with bacterial adherence and survivability, contributing to biofilm formation and influencing the expression of key virulence factors. This study yields initial insight into the functional roles of Sfm in APEC and provides a foundation for the effective control of E. coli in the poultry industry. Full article

Avian pathogenic Escherichia coli (APEC) poses a global threat to poultry health and public safety due to its high lethality, limited treatment options, and potential for zoonotic transmission via the food chain. However, long-term genomic surveillance remains limited, especially in countries like China where poultry farming is highly intensive. This study aimed to characterize the population structure, virulence traits, and antimicrobial resistance of 81 APEC isolates from diseased chickens collected over 16 years from Shandong and neighboring provinces in eastern China. The isolates were grouped into seven Clermont phylogroups, with A and B1 being dominant. MLST revealed 27 STs, and serotyping identified 29 O and 16 H antigens, showing high genetic diversity. The minor phylogroups (B2, C, D, E, G) encoded more virulence genes and had higher virulence-plasmid ColV carriage, with enrichment for iron-uptake, protectins, and extraintestinal toxins. In contrast, the dominant phylogroups A and B1 primarily carried adhesin and enterotoxin genes. Antimicrobial resistance was widespread: 76.5% of isolates were multidrug-resistant. The minor phylogroups exhibited higher tetracycline resistance (mediated by tet(A)), whereas the major phylogroups showed increased resistance to third- and fourth-generation cephalosporins (due to bla_CTX-M-type ESBL genes). These findings offer crucial data for APEC prevention and control, safeguarding the poultry industry and public health. Full article

In this study, we found that the deletion of the gene evfG in the type VI secretion system (T6SS) gene cluster significantly affected the motility of porcine extraintestinal pathogenic Escherichia coli (ExPEC) strain PCN033. Furthermore, the bacterial motility assay showed that ΔevfG mutants exhibited reduced motility compared to the parental strain. Transmission electron microscopy (TEM) showed a significant reduction in the number of flagella in the mutant ΔevfG when compared with PCN033. To further explore the reasons why the deletion of evfG affects the motility of PCN033, transcriptomic and metabolomic analyses were conducted. The omics analyses showed that 134 differentially accumulated metabolites and 2236 differentially expressed genes were identified between the mutant ΔevfG and the parental strain PCN033. The metabolome profile and functional annotation analyses indicated that the impaired motility of ΔevfG was connected to the downregulation of the expression levels of genes associated with the energy metabolism pathway and flagellar assembly. Our study provides a new insight into the diminished PCN033 motility induced by evfG deletion. Moreover, the candidate genes and metabolites regulated by the gene evfG in the T6SS, which was involved in the motility of PCN033, were reported in this study. Full article

Untreated water bodies are critical ecological niches where environmental conditions can drive the adaptive evolution of bacterial populations, enabling them to acquire new traits such as antibiotic-resistance genes. Escherichia coli is typically a commensal bacterium but can evolve into a pathogenic form, known as Diarrheagenic E. coli, responsible for both intestinal and extraintestinal diseases. This study focuses on the characterization of E. coli isolates from water samples collected from the Matasnillo River and the influence of the Juan Díaz Wastewater Treatment Plant (WWTP). While isolates from the Matasnillo River were classified as commensal, 18% of the isolates from the WWTP belonged to either phylogroups D or B2. Pathotype analysis revealed the presence of Entero-Toxigenic and Entero-Hemorrhagic E. coli in the WWTP. Moreover, Matasnillo River isolates exhibited resistance mainly to the quinolone ciprofloxacin, whereas those from the WWTP influent showed resistance to multiple broad-spectrum antibiotics. Sequencing analysis revealed the prevalence of the transmissible quinolone resistance qnrB19 among the Matasnillo River isolates and mutations conferring resistance to quinolone in gyrA, parC, and parE. These findings highlight the importance of monitoring antibiotic-resistant bacterial contamination in both freshwater and wastewater to mitigate the risk of the spread of resistant pathogens and potential epidemic outbreaks. Full article

Irrigation water can serve as a reservoir and transmission route for pathogenic Escherichia coli, posing a threat to food safety and public health. This study builds upon a previous survey conducted in Hermosillo, Sonora (Mexico), where 445 samples were collected from a local Honeydew melon farm and associated packing facilities. Among the 32 E. coli strains recovered, two strains, A34 and A51, were isolated from irrigation water and selected for further molecular characterization by PCR, due to their high pathogenic potential. Both strains were identified as hybrid aEPEC/STEC pathotypes carrying bfpA and stx1 virulence genes. Adhesion assays in HeLa cells revealed aggregative and diffuse patterns, suggesting enhanced colonization capacity. Phylogenetic analysis classified A34 within group B2 as associated with extraintestinal pathogenicity and antimicrobial resistance, while A51 was unassigned to any known phylogroup. Serotyping revealed somatic antigens shared with Shigella boydii 16, suggesting possible horizontal gene transfer or antigenic convergence. Antibiotic susceptibility testing showed resistance to multiple β-lactam antibiotics, including cephalosporins, linked to the presence of bla_CTX-M-151 and bla_CTX-M-9. Although no plasmid-mediated quinolone resistance genes were detected, resistance may involve efflux pumps or mutations in gyrA and parC. These findings are consistent with previous reports of E. coli adaptability in agricultural environments, suggesting potential genetic adaptability. While our data support the presence of virulence and resistance markers, further studies would be required to demonstrate mechanisms such as horizontal gene transfer or adaptive evolution. Full article

Escherichia coli contamination in poultry is a significant concern due to its potential to cause foodborne illness. The presence of extraintestinal pathogenic E. coli (ExPEC) strains in chicken carcasses can lead to severe human infections. This study investigates the prevalence, virulence, and antibiotic resistance of E. coli isolates from chicken carcasses processed in both wet market and industrial environments, with a focus on the detection capabilities of MALDI-TOF MS. A total of 119 E. coli isolates were obtained. Only a small proportion (5/119) carried enteropathogenic virulence genes. In contrast, 71.42% (85/119) of the isolates harbored multiple extraintestinal virulence genes. Among these, iucC and sitA, which are associated with systemic infections, were present in 68.24% (58/85) and 43.53% (37/85) of the isolates, respectively. Furthermore, 47.06% (56/119) of the isolates carrying at least two extraintestinal virulence genes were classified as ExPEC. Additionally, 94.6% (54/56) of ExPEC isolates were multidrug resistant (MDR), showing resistance to over three antibiotic classes, raising concerns about the spread of antibiotic resistance. MALDI-TOF MS profiling revealed significant heterogeneity among the ExPEC isolates, with no distinct clustering patterns based on processing environment or sampling site. These findings underscore the public health risks posed by ExPEC in poultry and emphasize the need for improved surveillance, stringent hygiene practices, and responsible antibiotic use in poultry production. Full article

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a foodborne pathogen that causes a variety of diseases, ranging from self-limiting gastroenteritis to life-threatening extra-intestinal diseases such as hemolytic uremic syndrome. EspF, an effector protein secreted by the type III secretion system of EHEC, is primarily responsible for the development of inflammatory colitis. Our previous study revealed that EspF interacts with the host Annexin A6 (ANXA6) protein and targets the endoplasmic reticulum (ER). Given the critical effects of ER stress on the host responses of gastroenteritis, we explored the role of EspF–ANXA6 interaction in ER stress. Caco-2 cells were infected with different strains of EHEC and transfected with modified plasmids to establish in vitro research models. Our results revealed that infection with espF-deletion EHEC strains significantly exacerbated ER stress. Specifically, the phosphorylation of eIF2α was elevated, and the expression levels of BiP, ATF4, and CHOP were increased by more than 15% compared to those in cells infected with wild-type EHEC strains. Further experiments showed that EspF co-localizes with BiP and down-regulates the PERK pathway. Meanwhile, the EspF–ANXA6 interaction could aggravate the inhibition of the PERK pathway and stimulate calcium influx to disturb ER homeostasis, eventually leading to apoptosis. Our findings suggest that the EspF–ANXA6 interaction could inhibit ER stress through the PERK pathway, which may limit cell-to-cell communication and block the clearance of bacteria in host cells. Full article

Pathogenic Escherichia coli can cause a variety of intestinal and extra-intestinal infections in humans and animals. The availability and subsequent misuse of antimicrobials, especially in poultry production systems, has contributed immensely to the emergence and spread of multidrug-resistant E. coli. This study investigated the genotypic characterization of colistin-resistant E. coli and selected antimicrobial-resistance encoding genes along with their phenotypic resistant pattern and the multiple antimicrobial resistant (MAR) index from village chickens in Kelantan. Sixty E. coli isolates obtained from a previous study’s stock culture were enriched and analyzed using routine microbiological methods: Kirby–Bauer disc diffusion method, minimum inhibitory concentration (MIC), and PCR amplification of E. coli species-specific and multidrug-resistance mcr-positive E. coli. All the isolates were confirmed as E. coli and 16.6% (10/60) were positive for mcr. Five isolates were positive for mcr-1, three for mcr-4, and two for mcr-9. The mcr-positive isolates showed varying degrees of resistance to different antimicrobials. The isolates were resistant to gentamicin (100%), chloramphenicol (100%), and tetracycline (89.4%) and susceptible to ceftaxidime (2.26%) and imipenem (18%). Furthermore, 100%, 94.7%, and 89.4% of isolates from village chickens belonged to phylogroup C, B2, and E, while 21.0% and 42.1% of the isolates belonged to phylogroup A and B1, respectively. Sequence types (STs) of selected E. coli isolates were further analyzed using multi-locus sequence typing, and 10 different STs were identified. This study showed the emerging threats of multidrug-resistant mcr-positive E. coli gene in village chickens that are believed to be raised with minimal or no antibiotics. Full article

Background: Extra-intestinal pathogenic Escherichia coli (ExPEC) represents a major global public health challenge due to its ability to cause diverse clinical infections, including urinary tract infections, bacteremia, neonatal meningitis, and sepsis. The growing prevalence of multidrug-resistant (MDR) ExPEC strains, which rapidly erode antibiotic efficacy, underscores vaccine development as a critical priority. Bioconjugate vaccines have emerged as a promising approach to mitigate ExPEC-associated infections. Methods and Results: In this study, we utilized protein glycan coupling technology (PGCT) based on oligosaccharyltransferase (OST) PglL to engineer a tetravalent bioconjugate vaccine targeting four predominant ExPEC serotypes (O1, O2, O6, and O25). We conducted a series of experiments to demonstrate the efficacy of the conjugate vaccine in eliciting humoral immune responses and inducing the production of specific antibodies against Escherichia coli O1, O2, O6, or O25 serotypes. Conclusions: This work establishes the first application of the O-linked PGCT system for engineering bioconjugate vaccines against ExPEC infections. Full article

Escherichia coli (E. coli) is a Gram-negative, commensal/pathogenic bacteria found in human intestines and the natural environment. Pathogenic E. coli is known as extra-intestinal pathogenic E. coli (ExPEC) or intestinal pathogenic E. coli (InPEC). InPEC E. coli strains are separated into six pathogenic groups, known as enteropathogenic (EPEC), enterotoxigenic (ETEC), enteroinvasive (EIEC), enteroaggregative (EAEC), enterohaemorrhagic (EHEC), and diffusely adherent (DAEC), that have various virulence factors that cause infection. Virulence factors refer to a combination of distinctive accessory traits that affect a broad range of cellular processes in pathogens. There are two important virulence factors that directly interact with cells to cause diarrhoeal diseases within the intestines: adhesion and colonization factors and exotoxins. Virulence factors are crucial for bacteria to overcome the host’s immune system and result in antibiotic resistance. Antibiotics are used to combat the symptoms and duration of infection by pathogenic E. coli. However, the misuse and overuse of antibiotics have led to the global concern of antibiotic resistance. Currently, the antibiotic colistin is the last-resort drug to fight infection caused by this bacterium. Antibiotic resistance can be achieved in two main ways: horizontal gene transfer and mutation in different genes. The genetic basis for developing antibiotic resistance in E. coli occurs through four mechanisms: limiting drug uptake, modification of the drug target, inactivation of the drug, and active efflux of the drug. These mechanisms use different processes to remove the antibiotic from the bacterial cell or prevent the antibiotic from entering the bacterial cell or binding to targets. This prevents drugs from working effectively, and bacteria can acquire antibiotic resistance. E. coli is classified into different phylogenetic groups (A, B1, B2, D1, D2, E, and clade I). It is a very versatile bacterium that can easily adapt to different environmental factors. The present review gathered information about the pathogenicity, antimicrobial resistance, and phylogenetics of E. coli. These aspects are interconnected; thus, it will provide information on tracking the spread of pathogenic strains and antibiotic resistance genes of different strains using phylogenetics and how antibiotic resistance genes evolve. Understanding genetic variation in E. coli will help in monitoring and controlling outbreaks and in developing novel antibiotics and treatment. The increasing rate of antibiotic resistance, and the ability of E. coli to evolve rapidly, suggest that in-depth research is needed in these areas. Full article

E. coli pathotypes, which cause extra-intestinal infections, pose significant public health challenges, emphasizing the need for virulence gene surveillance to understand their dynamics. Key virulence genes have been identified in E. coli from Andean community countries, predominantly linked to human and animal sources. However, detailed data on virulence profiles from environmental and food sources remain limited. This study utilized an in silico approach to analyze 2402 whole-genome sequences from EnteroBase, known for associations with antimicrobial resistance genes. Of the isolates, 30% were classified as ExPEC, averaging 39 virulence genes per isolate, with adhesin-related genes being the most predominant. These findings were consistent across human, environmental, animal, and food samples. Human and animal isolates exhibited greater diversity in adhesin, secreted factors, and toxin genes compared to other sources, whereas food samples contained the fewest factors. ST449 isolates exhibited an average of 50 virulence genes per genome, with secreted factors and adhesins equally represented, while ST131, ST38, and ST10 carried around 40 genes, predominantly adhesins. Overall, the diversity and frequency of virulence genes exceeded prior reports in the region, highlighting the importance of monitoring these traits to identify emerging patterns in pathogenic E. coli strains frequently subjected to antibiotic exposure. Full article

Extraintestinal pathogenic Escherichia coli (ExPEC) is a group of Escherichia coli strains that can cause severe infectious diseases outside the gastrointestinal tract, such as urinary tract infections, meningitis, septicemia, etc. We report a case of a calf herd infection by ExPEC with high rates of morbidity and mortality. The research purpose of this study was to thoroughly investigate the characteristics of the ExPEC responsible for the calf herd infection. Specifically, we aimed to understand the mechanisms underlying its multidrug resistance and high pathogenicity. Clinical samples were collected for the isolation and identification of ExPECs, cultured on MacConkey agar, and further tested by PCR for the uidA gene, 16S rRNA gene sequencing, and adhesion patterns on HEp-2 cells. The antimicrobial activity was determined using the disk diffusion method according to Clinical & Laboratory Standards Institute (CLSI) guidelines. The pathogenicity was assessed through the experimental infection of Kunming mice, tracking their survival and weight changes, and performing autopsies for bacterial counts and histopathological analysis. Additionally, whole-genome sequencing (WGS) and a comprehensive analysis were performed, including multilocus sequence typing (MLST), serotyping, drug-resistance gene analysis, virulence factor analysis, metabolic pathway analysis, and enrichment analysis, using various online tools and databases. An ExPEC strain named RZ-13 was responsible for this case and was identified as ST345 and O134: H21. Among the 14 antibiotics tested, 13 showed resistance, indicating that the RZ-13 strain is a multidrug-resistant (MDR) bacterium. The experimental infection of Kunming mice proved the greater pathogenicity of RZ-13 than that of CICC 24186. The comprehensive WGS revealed the presence of 28 antibiotic resistance genes and 86 virulence-related genes in the genome of the strain, corroborating its clinical manifestations of MDR and high pathogenicity. Our study isolated a MDR ExPEC strain, RZ-13, with a strong pathogenicity. This is the first case report of ExPEC leading to severe mortality in calf herds in China, underscoring the need for the rational use of antibiotics to reduce the risk of the generation and transmission of MDR bacteria from food-producing animals to ensure food safety and public health. Full article

Neonatal sepsis is a major cause of mortality in preterm infants, with Escherichia coli as one of the leading pathogens. Few studies have examined the interplay between virulence factors, resistance profiles, phylogroups, and clinical outcomes in this population. We analyzed 52 E. coli strains isolated from 49 preterm neonates diagnosed with sepsis at a tertiary-level hospital in Mexico. Strains underwent phylogenetic classification, virulence gene profiling, and antimicrobial resistance testing. PFGE was used to assess genetic relatedness and outbreak clusters. Clinical data were correlated with molecular findings. Phylogroups A and B2 accounted for 46% of strains. Phylogroup A exhibited notable virulence, with high prevalence of the pathogenicity island described in virulent extra-intestinal E. coli strains (PAI), aerobactin siderophore receptor AerJ (iutA), and yersiniabactin siderophore receptor (fyuA) genes, alongside significant resistance profiles. PFGE identified two dominating branches. Branch A, comprising phylogroups A and B2, displayed high resistance and was prevalent in the neonatal intensive care unit. Branch C, with phylogroups A and D, showed less multidrug resistance but was significantly associated with maternal chorioamnionitis. This study redefines E. coli pathogenicity in neonatal sepsis, highlighting the virulence of traditionally non-pathogenic phylogroups. High virulence strains were associated with more severe outcomes. These findings underscore the need for enhanced strategies in targeted prevention, improved diagnostics, and tailored treatments for high-risk preterm populations. Full article

The functions of bacterial plasmid-encoded toxin–antitoxin (TA) systems are unambiguous in the sense of controlling cells that fail to inherit a plasmid copy. However, its role in chromosomal copies is contradictory, including stress-response-promoting fitness and antibiotic treatment survival. A hybrid pathogenic Escherichia coli strain may have the ability to colonize distinct host niches, facing contrasting stress environments. Herein, we determined the influence of multiple environmental stress factors on the bacterial growth dynamic and expression profile of previously described TA systems present in the chromosome of a hybrid atypical enteropathogenic and extraintestinal E. coli strain. Genomic analysis revealed 26 TA loci and the presence of five type II TA systems in the chromosome. Among the tested stress conditions, osmotic and acid stress significantly altered the growth dynamics of the hybrid strain, enhancing the necessary time to reach the stationary phase. Using qPCR analyses, 80% of the studied TA systems were differentially expressed in at least one of the tested conditions, either in the log or in the stationary phase. These data indicate that type II TA systems may contribute to the physiology of pathogenic hybrid strains, enabling their adaptation to different milieus. Full article

Background: Foodborne diseases are a serious public health concern, and food-producing animals are a major source of contamination. Methods: The present study analysed Escherichia coli and Salmonella spp. isolated from faecal samples of 100 fattening pigs and from 52 samples of pork meat. Results: The results showed that the majority of the analysed meat samples were considered satisfactory in terms of microbiological quality (92.3% for E. coli and 94.2% for Salmonella spp.). Salmonella spp. was identified in 5.8% of the meat samples, whereas E. coli was detected in 89.5% of all samples (69.2% in meat and 100% in faecal samples). Furthermore, 1.9% of the faecal samples contained Shiga-toxin-producing E. coli and 3.9% contained enterotoxigenic E. coli. All sequenced isolates presented virulence genes for extraintestinal pathogenic E. coli. Moreover, 75.0% of E. coli isolates from meat and 71.8% from faeces samples showed antibiotic resistance, with 40.7% and 51.4%, respectively, being multidrug-resistant (MDR). The most prevalent resistances were to tetracycline, ampicillin, and sulfamethoxazole, and one E. coli isolate showed resistance to extended-spectrum β-lactamase. Conclusions: This study highlights the role of pigs as a potential source of human contamination and the importance of a One Health approach to ensure food safety and to promote public health. Full article