Search Results (37)

Background/Objectives: The presence of multi-drug-resistant (MDR) bacteria in healthy individuals poses a significant public health concern, as these strains may contribute to or even facilitate the dissemination of antibiotic resistance genes (ARGs) and virulence factors. In this study, we investigated the genomic features of antimicrobial-producing Escherichia coli strains from the gut microbiota of healthy individuals in Singapore. Methods: Using a large-scale screening approach, we analyzed 3107 E. coli isolates from 109 fecal samples for inhibitory activity against E. coli DH5α and performed whole-genome sequencing on 37 representative isolates. Results: Our findings reveal genetically diverse strains, with isolates belonging to five phylogroups (A, B1, B2, D, and F) and 23 unique sequence types (STs). Bacteriocin gene clusters were widespread (92% of isolates carried one or more bacteriocin gene clusters), with colicins and microcins dominating the profiles. Notably, we identified an hcp-et3-4 gene cluster encoding an effector linked to a Type VI secretion system. Approximately 40% of the sequenced isolates were MDR, with resistance for up to eight antibiotic classes in one strain (strain D96). Plasmids were the primary vehicles for ARG dissemination, but chromosomal resistance determinants were also detected. Additionally, over 55% of isolates were classified as potential extraintestinal pathogenic E. coli (ExPEC), raising concerns about their potential pathogenicity outside the intestinal tract. Conclusions: Our study highlights the co-occurrence of bacteriocin genes, ARGs, and virulence genes in gut-residing E. coli, underscoring their potential role in shaping microbial dynamics and antibiotic resistance. While bacteriocin-producing strains show potential as probiotic alternatives, careful assessment of their safety and genetic stability is necessary for therapeutic applications. Full article

Background/Objectives: Extraintestinal pathogenic Escherichia coli (ExPEC) strains, particularly those belonging to phylogenetic group B2, are clinically significant due to their frequent involvement in urinary tract infections (UTIs) and display antimicrobial resistance profiles. While the association of phylogroup B2 E. coli with human urinary tract infections is well established, the growing number of reports of ExPEC strains in canine UTIs highlights their clinical relevance in small animal medicine and raises concerns about their potential role in zoonotic transmission. This study investigated the microbiological and genomic features of E. coli strains isolated from dogs with UTIs in São Paulo, Brazil. Methods: Between March and May 2023, a total of 60 E. coli strains from canine UTIs were screened for antimicrobial susceptibility and phylotyping. Accordingly, four strains (6.6%) were identified as multidrug-resistant (MDR) or belonging to phylogroup B2 and, therefore, were submitted for characterization by whole-genome sequencing. Results: The four E. coli strains exhibited diverse antimicrobial resistance profiles, including resistance to third- and fourth-generation cephalosporins and fluoroquinolones. Phylogenetic groups B1, B2, and G, and sequence types (ST) 73, ST224, ST1193, and ST12960 were identified. The resistome included clinically important β-lactam resistance genes, such as bla_CTX-M-55 and bla_CMY-2, as well as mutations in the quinolone-resistance-determining region. Virulence factors associated with ExPEC pathogenesis, including adhesion, iron acquisition, immune evasion, and toxin, were detected. Plasmid sequences were identified as carrying antimicrobial resistance and virulence genes, highlighting the potential for horizontal gene transfer. Conclusions: Our findings underscore the importance of genomic surveillance in companion animals to better understand the epidemiology of ExPEC strains and monitor the spread of MDR strains. Full article

Antimicrobial resistance (AMR), particularly due to extended-spectrum β-lactamases (ESBLs) and carbapenemases (CPs), poses a critical threat to global health. This study aimed to characterize the molecular epidemiology, resistance profiles, and genomic features of ESBL- and CP-producing Escherichia coli and Klebsiella pneumonaie (ESBL/CP-Ec/Kp) isolates from a Spanish hospital (2020–2024) and explore links to environmental reservoirs like white storks foraging at a nearby landfill. A total of 121 clinical Ec/Kp isolates (55 ESBL-Ec, 1 CP-Ec, 35 ESBL-Kp, 17 CP-Kp, 13 ESBL+CP-Kp) underwent phenotypic testing, PCR, and whole-genome sequencing (WGS). Analyses included phylogenomics (cgMLST), detection of AMR genes, plasmid typing, and comparative genomics. Among ESBL-Ec, bla_CTX-M-15 was the most prevalent (60.0%), and one CP-Ec carrying bla_NDM-5 was identified. WGS of 44 selected ESBL/CP-Ec isolates revealed a variety of AMR genes, and 56.8% of isolates carried class one integrons (56.8%). IncF-type plasmids predominated, and 84.1% of isolates were assigned as ExPEC/UPEC. The lineage ST131 dominated (75%), with IncF-bla_CTX-M-15-carrying plasmids. Among the 18 ESBL/CP-Kp isolates sequenced, the lineage ST307 was the most frequent (44.4%), followed by ST15 and ST11, carrying a diversity of AMR determinants and plasmids (IncFIB(K), IncL, ColpVC). Virulence included ybt loci in ICEKp; hypervirulence genes were absent. Genomic analysis of 62 clinical isolates (44 Ec, 18 Kp) showed close phylogenetic links to stork-derived strains, with ST131-Ec and ST307-Kp from humans and birds differing just by ≤22 and ≤10 ADs, respectively, with a conserved plasmid content (i.e., IncL-bla_OXA-48, IncFIB(K)-bla_CTX-M-15). High-risk ESBL/CP-Ec/Kp clones persist across clinical and environmental contexts. WGS-based surveillance is key for understanding AMR spread and guiding interventions. Results support a One Health approach to combat AMR through cross-sector collaboration. Full article

Sternal bursitis is an underexplored lesion in poultry, often overlooked in microbiological diagnostics. In this study, we characterized 36 Escherichia coli isolates recovered from sternal bursitis in broiler chickens, combining phenotypic antimicrobial susceptibility testing, PCR-based screening, and whole genome sequencing (WGS). The genetic analysis revealed a diverse population spanning 15 sequence types, including ST155, ST201, and ST58. Resistance to tetracycline and ciprofloxacin was common, and several isolates carried genes encoding β-lactamases, including blaTEM-1B. Chromosomal mutations associated with quinolone and fosfomycin resistance (e.g., gyrA p.S83L, glpT_E448K) were also identified. WGS revealed a high number of virulence-associated genes per isolate (58–96), notably those linked to adhesion (fim, ecp clusters), secretion systems (T6SS), and iron acquisition (ent, fep, fes), suggesting strong pathogenic potential. Many isolates harbored virulence markers typical of ExPEC/APEC, such as iss, ompT, and traT, even in the absence of multidrug resistance. Our findings suggest that E. coli from sternal bursitis may act as reservoirs of resistance and virulence traits relevant to animal and public health. This highlights the need for including such lesions in genomic surveillance programs and reinforces the importance of integrated One Health approaches. Full article

Diarrhea in alpaca crias significantly impacts livestock health in high-altitude regions, with Escherichia coli as a common pathogen. This study analyzed 10 E. coli isolates from diarrheic and healthy alpacas using whole-genome sequencing to assess genetic diversity, virulence factors, and antibiotic resistance. Predominant sequence types (ST73, ST29), serotypes (O22:H1, O109:H11), and phylogroups (B2, B1, A) were identified. Virulence profiling revealed ExPEC-like and EPEC pathotypes, while resistance genes for β-lactams (blaEC-15), fosfomycin (glpT_E448K), and colistin (pmrB) were prevalent. These findings highlight the need for genomic surveillance and antimicrobial stewardship to manage E. coli infections in alpacas and reduce public health risks. 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

To determine the etiological agents responsible for acute pneumonia in puppies in China, this study utilized bronchoalveolar lavage (BAL) fluid extraction to enable the isolation, culture, biochemical identification, and 16S rRNA PCR amplification of the pathogens. Following preliminary identification, the pathogens underwent analysis for antibiotic resistance phenotypes and resistance genes. Additionally, the study examined the presence of virulence genes, conducted multilocus sequence typing (MLST), and performed whole-genome sequencing (WGS). The findings revealed that all four isolated pathogens were characterized as extraintestinal pathogenic Escherichia coli (ExPEC). The examined ExPEC strains demonstrated resistance to cephalosporins, tetracyclines, and penicillins, while remaining susceptible to aminoglycosides, beta-lactamase inhibitors, carbapenems, chloramphenicols, and sulfonamides. An analysis of virulence genes identified the presence of eight genes, namely CNF-I, fyuA, fimC, papC, ompA, fimH, irp2, and iroN, which are implicated in their invasiveness and potential to inflict tissue damage. The MLST analysis revealed that all ExPEC strains were classified under either sequence type ST131 (Achtman database) or ST43 (Pasteur database). The study further determined that these strains were absent in the kennel’s drinking water source, thereby ruling out water contamination as a potential factor in the emergence of ST131-type ExPEC. This study offers a theoretical framework and empirical evidence for elucidating the potential pathogenic mechanisms and clinical therapeutic strategies of ExPEC in the etiology of acute pneumonia in puppies. Full article

Escherichia coli is a frequent pathogen isolated from bloodstream infections. This study aimed to characterize the genetic features of EC092, an E. coli strain isolated from bacteremia that harbors enteroaggregative E. coli (EAEC) genetic markers, indicating its hybrid pathogenic potential. Whole-genome sequencing showed that EC092 belongs to phylogroup B1, ST278, and serotype O165:H4. Genes encoding virulence factors such as fimbriae, toxins, iron-uptake systems, autotransporter proteins (Pet, Pic, Sat, and SepA), and secretion systems were detected, as well as EAEC virulence genes (aggR, aatA, aaiC, and aap). EC092 was found to be closely related to the other EAEC prototype strains and highly similar in terms of virulence to three EAEC strains isolated from diarrhea. The genomic neighborhood of pet, pic, sat, sepA, and the EAEC virulence genes of EC092 and its three genetically related fecal EAEC strains showed an identical genomic organization and nucleotide sequences. Also, EC092 produced and secreted Pet, Pic, Sat, and SepA in the culture supernatant and resisted the bactericidal activity of normal human serum. Our results demonstrate that the strain EC092, isolated from bacteremia, is a hybrid pathogenic extraintestinal E. coli (ExPEC)/EAEC with virulence features that could mediate both extraintestinal and intestinal infections. Full article

This study aimed to identify contamination sources in raw milk and cheese on small farms in Brazil by isolating Escherichia coli at various stages of milk production and cheese manufacturing. The study targeted EAEC, EIEC, ETEC, EPEC, STEC, and ExPEC pathotypes, characterizing isolates for the presence of virulence genes, phylogroups, antimicrobial susceptibility, and phylogenetic relationships using PFGE and MLST. The presence of antimicrobial resistance genes and serogroups was also determined. Three categories of E. coli were identified: pathogenic, commensal, and ceftriaxone-resistant (ESBL) strains. Pathogenic EPEC, STEC, and ExPEC isolates were detected in milk and cheese samples. Most isolates belonged to phylogroups A and B1 and were resistant to antimicrobials such as nalidixic acid, ampicillin, kanamycin, streptomycin, sulfisoxazole, and tetracycline. Genetic analysis revealed that E. coli with identical virulence genes were present at different stages within the same farm. The most frequently identified serogroup was O18, and MLST identified ST131 associated with pathogenic isolates. The study concluded that E. coli was present at multiple points in milk collection and cheese production, with significant phylogroups and high antimicrobial resistance. These findings highlight the public health risk posed by contamination in raw milk and fresh cheese, emphasizing the need to adopt hygienic practices to control these microorganisms. Full article

The present study shows the genomic characterization of three pathogenic Escherichia coli hybrid strains. All strains were previously characterized as diarrheagenic pathotypes (DEC), obtained from feces. The three sequenced strains have genes that encode adhesins (fimH and iha) and iron uptake systems (iucC and iutA). Antibiotic resistance genes were also found for fluoroquinolone and aminoglycoside families in the three strains. The presence of genomic islands (GIs) in the sequenced study strains presented 100% identity (Ec-25.2) and 99% identity (Ec-36.1) with previously reported Extraintestinal Pathogenic E. coli (ExPEC) strains. The Ec-36.4 strain shared a 99% identity with GI from the Enterotoxigenic E. coli (ETEC) pathotype of the diarrheagenic E. coli strain. Ec-25.2 belongs to ST69 and harbors a FimH27 variant, while Ec-36.1 and Ec-36.4 belong to ST4238 and share a FimH54 variant. Four incompatibility groups associated with conjugative plasmids were identified (IncFIB, IncF11, IncI1, and IncB/O/K/Z), as well as Insertion Sequences and MITEs elements. Full article

The pyelonephritis-associated fimbria (P fimbria) is one of the most recognized adhesion determinants of extraintestinal pathogenic Escherichia coli strains (ExPECs). Twelve variants have been described for the gene encoding the P fimbria major structural subunit PapA and three variants for the gene encoding the adhesin subunit PapG. However, their distribution among the ExPEC diversity has not been comprehensively addressed. A complete landscape of that distribution might be valuable for delineating basic studies about the pathogenicity mechanisms of ExPECs and following up on the evolution of ExPEC lineages, particularly those most epidemiologically relevant. Therefore, we performed a massive descriptive study to detect the papA and papG variants along different E. coli genotypes represented by genomic sequences contained in the NCBI Assembly Refseq database. The most common papA variants were F11, F10, F48, F16, F12, and F7-2, which were found in significant association with the most relevant ExPEC genotypes, the phylogroups B2 and D, and the sequence types ST95, ST131, ST127, ST69, ST12, and ST73. On the other hand, the papGII variant was by far the most common followed by papGIII, and both were also found to have a significant association with common ExPEC genotypes. We noticed the presence of genomes, mainly belonging to the sequence type ST12, harboring two or three papA variants and two papG variants. Furthermore, the most common papA and papG variants were also detected in records representing strains isolated from humans and animals such as poultry, bovine, and dogs, supporting previous hypotheses of potential cross-transmission. Finally, we characterized a set of 17 genomes from Chilean uropathogenic E. coli strains and found that ST12 and ST73 were the predominant sequence types. Variants F7-1, F7-2, F8, F9, F11, F13, F14, F16, and F48 were detected for papA, and papGII and papGIII variants were detected for papG. Significant associations with the sequence types observed in the analysis of genomes contained in the NCBI Assembly Refseq database were also found in this collection in 16 of 19 cases for papA variants and 7 of 9 cases for the papG variants. This comprehensive characterization might support future basic studies about P fimbria-mediated ExPEC adherence and future typing or epidemiological studies to monitor the evolution of ExPECs producing P fimbria. Full article

Uropathogenic Escherichia coli (UPEC) is the main cause of urinary tract infections (UTIs) and carries virulence and resistance factors often found in mobilizable genetic elements, such as plasmids or pathogenicity islands (PAIs). UPEC is part of the extraintestinal pathogenic E. coli (ExPEC), but hybrid strains possessing both diarrheagenic E. coli (DEC) and ExPEC traits, termed “hypervirulent”, present a significant health threat. This study assessed the prevalence of UPEC PAIs, ExPEC sequence types (ST), DEC genes, carbapenemase and extended-spectrum β-lactamase (ESBL) phenotypes, resistance genotypes, and plasmids in 40 clinical isolates of UPEC. Results showed that 72.5% of isolates had PAIs, mainly PAI IV₅₃₆ (53%). ESBL phenotypes were found in 65% of β-lactam-resistant isolates, with 100% of carbapenem-resistant isolates producing carbapenemase. The predominant ESBL gene was bla_CTX-M-2 (60%), and the most common resistance gene in fluoroquinolone and aminoglycoside-resistant isolates was aac(6′)Ib (93%). Plasmids were present in 57% of isolates, and 70% belonged to the ST131 clonal group. Molecular markers for DEC pathotypes were detected in 20 isolates, with 60% classified as hybrid pathotypes. These findings indicate significant pathogenic potential and the presence of hybrid pathotypes in E. coli UTI clinical isolates in the Mexican population. Full article

Extraintestinal pathogenic Escherichia coli (ExPEC) account for over 80% and 60% of bacterial urinary tract infections (UTIs) in humans and animals, respectively. As shared uropathogenic E. coli (UPEC) strains have been previously reported among humans and pets, our study aimed to characterize E. coli lineages among UTI isolates from dogs and cats and to assess their overlaps with human UPEC lineages. We analysed 315 non-duplicate E. coli isolates from the UT of dogs (198) and cats (117) collected in central Germany in 2019 and 2020 utilizing whole genome sequencing and in silico methods. Phylogroup B2 (77.8%), dog-associated sequence type (ST) 372 (18.1%), and human-associated ST73 (16.6%), were predominant. Other STs included ST12 (8.6%), ST141 (5.1%), ST127 (4.8%), and ST131 (3.5%). Among these, 58.4% were assigned to the ExPEC group and 51.1% to the UPEC group based on their virulence associated gene (VAG) profile (ExPEC, presence of ≥VAGs: papAH and/or papC, sfa/focG, afaD/draBC, kpsMTII, and iutA; UPEC, additionally cnf1 or hlyD). Extended-spectrum cephalosporin (ESC) resistance mediated by extended-spectrum β-lactamases (ESBL) and AmpC-β-lactamase was identified in 1.9% of the isolates, along with one carbapenemase-producing isolate and one isolate carrying a mcr gene. Low occurrence of ESC-resistant or multidrug-resistant (MDR) isolates (2.9%) in the two most frequently detected STs implies that E. coli isolated from UTIs of companion animals are to a lesser extent associated with resistance, but possess virulence-associated genes enabling efficient UT colonization and carriage. Detection of human-related pandemic lineages suggests interspecies transmission and underscores the importance of monitoring companion animals. Full article

The misuse of antibiotics is accelerating antimicrobial resistance (AMR) in Escherichia coli isolated from farm animals. The genomes of ten multidrug-resistant (MDR) E. coli isolates from pigs were analyzed to determine their sequence types, serotypes, virulence, and AMR genes (ARGs). Additionally, the relationship was evaluated adding all the available genomes of Peruvian E. coli from humans using the cgMLST + HierCC scheme. Two aEPEC O186:H11-ST29 were identified, of which H11 and ST29 are reported in aEPEC isolates from different sources. An isolate ETEC-O149:H10-ST100 was identified, considered a high-risk clone that is frequently reported in different countries as a cause of diarrhea in piglets. One ExPEC O101:H11-ST167 was identified, for which ST167 is an international high-risk clone related to urinary infections in humans. We identified many ARGs, including extended-spectrum β-lactamase genes, and one ETEC harboring the mcr-1 gene. CgMLST + HierCC analysis differentiated three clusters, and in two, the human isolates were grouped with those of swine in the same cluster. We observed that Peruvian swine MDR E. coli cluster with Peruvian E. coli isolates from healthy humans and from clinical cases, which is of great public health concern and evidence that AMR surveillance should be strengthened based on the One Health approach. Full article