Identification and Genomic Characterization of Escherichia albertii in Migratory Birds from Poyang Lake, China

Genomic insights and epidemiology of mcr-1-Carrying Escherichia albertii isolated from agricultural soil in China

BACKGROUND

Polymyxins are critical in treating multidrug-resistant Gram-negative bacteria infections, yet their overuse has spurred the emergence of polymyxin-resistant pathogens globally. This study aims to analyze the genomic characteristics of the Escherichia albertii strain 6S-65-1 carrying the mcr-1 gene and to investigate the global epidemiology of mcr-1-carrying E. albertii strains.

RESULTS

In this study, we identified and analyzed a polymyxin-resistant Escherichia albertii strain (6S-65-1) carrying the mcr-1 gene, isolated from agricultural soil in China. Whole-genome sequencing and comparative genomic analyses revealed two chromosomal integrations of the mcr-1 gene within Tn6330 transposon structures, indicating its capacity for horizontal gene transfer. Strain 6S-65-1 also harbors other antimicrobial resistance genes, including tet(A), sul3, and aph (3')-Ia, enhancing its resistance profile. Comparative genomic analysis of E. albertii genomes in the NCBI database revealed that mcr-1-carrying E. albertii strains are geographically restricted to China and Japan, and have been isolated from both animals and humans. Phylogenetic analysis revealed that strain 6S-65-1 was most closely related to a human-derived strain from Japan (SAMD00164101), with both strains carried virulence genes (cdt, paa, and eae) that enable them to form attaching and effacing (A/E) lesions. Among all publicly available ST4619 E. albertii genomes, strain 6S-65-1 is the first to carry the mcr-1 gene.

CONCLUSION

Our findings offer new insights into the epidemiology and genomic features of mcr-1-carrying E. albertii, underscoring the need for targeted management strategies to curb its spread. These findings underscore the importance of "One Health" approaches to antimicrobial resistance, which require coordinated efforts across human, animal and the environmental health sectors.

Cases of Isolation of Escherichia albertii Strains from Commercial Quails with Gastroenteritis in Russia

Escherichia albertii is a lactose-negative Escherichia that causes gastritis and enteritis in humans. An analysis of possible sources of infection points out that poultry may be a significant reservoir for this pathogen. The question of whether E. albertii can cause infections in poultry is still unanswered. Our article describes the isolation of E. albertii, for the first time in Russia, from the intestines of birds on a quail farm and a characterization of obtained cultures. We isolated different bacteria from pathological poultry material using bacteriological methods and ruled them out as probable causes for enteritis. The biochemical identification of E. albertii and antibiotic sensitivity were performed using a Vitek-2 Compact instrument. Bacterial identification was carried out using the MALDI-TOF Biotyper instrument. E. albertii-specific genes, virulence factor genes, and microcin genes were detected by real-time PCR. It was concluded that E. albertii isolated from sites of intestinal inflammation are a potential cause of enteritis and high poultry mortality-up to 15% of total livestock for 10- to 20-day-old quails. One of the E. albertii culture differed from the main group of Escherichia by its biochemical properties, and subsequent PCR analysis showed a lack of the intimin gene (eae). We describe the first occasion of infection caused by E. albertii in industrial quails. During the study, it was found that, according to the molecular-genetic and phenotypic properties of isolated strains in quails, there were at least two clonal groups of E. albertii differing in antibiotic resistance, biochemical indices, and presence of the eae (intimin) gene.

Whole-genome-based characterization of Escherichia albertii strains isolated from paediatric diarrhoeal cases in Kolkata, India

Escherichia albertii is a Gram-negative facultative anaerobic bacterium that causes diarrhoea in humans. This study shows the isolation of E. albertii from hospitalized paediatric diarrhoeal cases and genome-based characteristics with putative virulence factors and antimicrobial resistance. E. albertii isolates were identified by species-specific PCR, targeting the gene encoding cytolethal distending toxin (Ea-cdt). The genome of E. albertii was sequenced to identify (i) genes encoding virulence factors (ii) antibiotic resistance-encoding genes, including the mobile genetic elements and (iii) core gene-based phylogenetic relationships and pan-genome features. A total of 10 (1.2%) E. albertii isolates were isolated from 854 faecal samples, of which 6 (60%) were found as the sole pathogen and the remaining 4 (40%) were identified along with other pathogens, such as enteroaggregative Escherichia coli, rotavirus and adenovirus. Patients from whom E. albertii was isolated presented cholera-like diarrhoea, i.e. with watery stool (60%) with moderate dehydration (100%), fever (20%) and abdominal pain (20%). The antimicrobial susceptibility testing of E. albertii showed that most of the isolates were susceptible or reduced susceptible to most of the antibiotics except resistance to erythromycin (80%), tetracycline (50%), nalidixic acid (40%), ampicillin (40%), doxycycline (30%) and ceftriaxone (20%). In the whole-genome sequence, E. albertii isolates revealed several virulence-encoding genes, namely the intimin (eae, E. coli attaching and effacing), the cytolethal distending toxin type II subunit A (cdt-IIA), adhesion (paa, porcine attaching- and effacing-associated), non-LEE (locus of enterocyte effacement) encoded effector A (nleA) and antimicrobial resistance genes (ARGs) conferring resistance to tetracycline (tetA, tetR), sulphonamides (sul2), fluoroquinolones (qnrS) and beta-lactamases (bla CTX-M, blaTEM). The SNP-based phylogenetic analysis of 647 whole genomes of E. albertii isolates from the National Center for Biotechnology Information databases did not reveal any comparable clustering pattern based on the biological source and place of isolation. The genome of some of the E. albertii was closely related to those of the isolates from China and the United Kingdom. The PFGE patterns revealed that most of the E. albertii isolates were distinct clones. This study reports on the extensive genome analysis of diarrhoea-associated E. albertii harbouring multiple virulence and ARGs.

Occurrence and cross contamination of Escherichia albertii in retail chicken outlets in Bangladesh

Escherichia albertii is an emerging zoonotic pathogen linked to human gastrointestinal illnesses, with poultry meats being considered as a key source of human infections. However, there is little information regarding the distribution and characteristics of this bacterium in Bangladesh. This study investigated the occurrence, antimicrobial resistance, and virulence of E. albertii in chicken meats from retail outlets in Bangladesh. We collected samples from 61 dressed chickens across 17 retail shops from 4 upazilas, along with swabs from cloaca, processing utensils, and worker hands. Detection of E. albertii by species-specific PCR revealed substantial occurrence of E. albertii in retail chicken meat (63.9 %), cloaca (71.4 %), human hand (45.5 %), bleeding cone (13.3 %) and blade (10 %). Almost all the E. albertii isolates (94.4 %) exhibited resistance to at least one of the tested antimicrobials, among which 50 % were multidrug resistant, including resistance to clinically relevant antimicrobials such as tetracycline, ampicillin, gentamicin, kanamycin, nalidixic acid and ciprofloxacin. Whole genome sequencing analysis identified the presence of corresponding antimicrobial resistance genes and critical virulence genes (eae, Eacdt). Notably, although wgSNP-based phylogenetic analysis showed the genomic diversity of the isolates, some of the isolates from the same shop displayed clonal relationships among meats, cloacal swabs, and human hand swabs, indicating contamination during processing. These findings highlight the public health risk posed by E. albertii in retail poultry, underlining the poultry's role as a potential vector for zoonotic transmission and the need for improved biosecurity and antimicrobial management practices in poultry production.

Genomic characterization of multidrug-resistant Escherichia albertii of fish origin-first isolation and insights into a potential food safety threat

Introduction

Escherichia albertii is an emerging food-borne pathogen with zoonotic potential which is often under-reported due to misidentifications.

Materials and methods

The current study identified E. albertii from retail fish sold in market which was confirmed by phenotypic (colorless colonies on Xylose-Rhamnose-Melibiose MacConkey Agar), genotypic (dual target uniplex PCR-based detection) and genomic methods (CheckM analysis). In this paper we report the phenotypic characters of the isolate and genomic features such as resistome, virulome and mobilome followed by in silico O and H antigen based typing and comparative phylogenomics using various tools (RAST, RGI v6.0.0, ABRicate v1.0.1, PathogenFinder v1.1, PlasmidFinder v2.0, BacAnt v3.3.1, Phigaro v2.4.0, MAFFT v7.490, FigTree v1.4.4).

Results and discussion

Multidrug resistance was identified with reduced susceptibility to gentamicin, azithromycin, ceftazidime and cefotaxime with a Multiple Antibiotic Resistance (MAR) index of 0.33. Clinically important virulence genes such as eae, cdt, east1 formed a part of the virulome and the probability of being pathogenic to humans was found to be 0.883. The genome was found to harbor mobile genetic elements such as plasmids [IncFIA, IncFIB(pB171), IncFII(pSE11)], transposons (Tn3411, Tn6292) and prophages (Siphoviridae, Myoviridae, Podoviridae). Various typing methods such as biotyping, multilocus sequence typing and in silico O and H antigen typing classified the isolate into biotype 3, multi locus sequence type 4596, O-genotype 4 and H-genotype 1. Phylogenomically, the isolate was placed close to isolate from neighboring country of China. Identification of virulent multidrug-resistant E. albertii from new food source such as fishes increases the risk for fish eating population and necessitates the requirement of further elucidation and development of appropriate control strategies.

Differential Cytotoxic Effects of Cell-Free Supernatants of Emerging Pathogens Escherichia albertii and Escherichia fergusonii on Four Cell Lines Reveal Vero Cells as a Putative Candidate for Cytotoxicity Analysis

Escherichia albertii and Escherichia fergusonii are recognized as emerging pathogens with zoonotic potential. Despite their increasing importance, there is a paucity of data on the cytotoxicity of these two pathogens. Therefore, in the present study, we investigated the cytotoxic potentials of the cell-free supernatants from 10 E. albertii and 15 E. fergusonii isolates for their cytotoxic effects on four different cell lines (CHO, Vero, HeLa, and MDCK). All E. albertii isolates (100%) and all but one E. fergusonii (93.33%) were cytotoxic. E. albertii isolates produced similar cytotoxicity titres across the cell lines, whereas the Vero cell was found to be the most sensitive to toxins produced by E. fergusonii (p < 0.05), followed by HeLa and CHO cells. MDCK was the least sensitive cell line to E. fergusonii toxins (p < 0.05). PCR detection of cytotoxicity-associated genes (cdtB, stx1, and stx2) indicated uniform possession of cdtB gene by all E. albertii isolates, while stx1 and stx2 genes were harboured neither by E. albertii, nor E. fergusonii. Taken together, our results provided experimental evidence of the cytotoxic effects of these two emerging pathogens, and Vero cells were identified as an optimal candidate to study the cytotoxic effects of E. albertii and E. fergusonii.

Characterization of Escherichia coli strains producing Shiga Toxin 2f subtype from domestic Pigeon

Shiga toxin-producing Escherichia coli (STEC) can cause mild diarrhea even severe hemolytic uremic syndrome (HUS). Shiga toxin (Stx) is the primary virulence factor. Two Stx types and several subtypes have been identified. STEC strains encoding stx2f (Stx2f-STECs) are frequently identified from pigeons. Stx2f was initially considered to be associated with mild symptoms, more recently Stx2f-STECs have been isolated from HUS cases, indicating their pathogenic potential. Here, we investigated the prevalence of Stx2f-STECs among domestic pigeons in two regions in China, characterized the strains using whole-genome sequencing (WGS), and assessed the Stx2f transcriptions. Thirty-two Stx2f-STECs (4.36%) were culture-positive out of 734 fecal samples (one strain per sample). No other stx subtype-containing strain was isolated. Four serotypes and two sequence types were determined, and a novel sequence type ST15057 was identified. All strains harbored the E. coli attaching and effacing gene eae. Two types of Stx2f prophages were assigned. Stx2f-STECs showed variable Stx transcription levels induced by mitomycin C. Whole genome single-nucleotide polymorphism (wgSNP) analysis revealed different genetic backgrounds between pigeon-derived strains and those from diarrheal or HUS patients. In contrast, pigeon-derived Stx2f-STECs from diverse regions exhibited genetic similarity. Our study reports the prevalence and characteristics of Stx2f-STECs from pigeons in China. The pigeon-derived strains might pose low public health risk.

An outbreak associated with Escherichia albertii in a junior high school, China

Escherichia albertii is an emerging foodborne enteropathogen associated with infectious diarrhoea in humans. In February 2023, an outbreak of acute gastroenteric cases was reported in a junior high school located in Hangzhou, Zhejiang province, China. Twenty-two investigated patients presented diarrhoea (22/22, 100%), abdominal pain (21/22, 95.5%), nausea (6/22, 27.3%), and vomiting (3/22, 13.6%). E. albertii strains were successfully isolated from anal swabs collected from six patients. Each isolate was classified as sequence type ST2686, harboured eae-β gene, and carried both cdtB-I and cdtB-II subtypes, being serotyped as EAOg32:EAHg4 serotype. A comprehensive whole-genome phylogenetic analysis revealed that the six isolates formed a distinct cluster, separate from other strains. These isolates exhibited minimal genetic variation, differing from one another by 0 to 1 single nucleotide polymorphism, suggesting a common origin from a single clone. To the best of our knowledge, this represented the first reported outbreak of gastroenteritis attributed to E. albertii outside of Japan on a global scale.

Genetic Diversity and Expression of Intimin in Escherichia albertii Isolated from Humans, Animals, and Food

Escherichia albertii (E. albertii) is an emerging diarrheagenic pathogen associated with sporadic infections and human gastroenteric outbreaks. The eae gene, which encodes intimin in the locus of enterocyte effacement (LEE) operon, contributes to the establishment of the attaching and effacing (A/E) lesion. Increasing collection of E. albertii strains from various sources has resulted in a rapid increase in the number of eae subtypes. This study systematically investigated the prevalence and genetic diversity of eae among E. albertii strains isolated from humans, animals, and food. The eae gene was present in 452/459 (98.5%) strains and 23 subtypes were identified including two novel subtypes, named eae-α11 and η3. The eae-σ subtype was the most predominant among humans, animals, and food-derived strains, while eae-γ3, τ, and α11 were unique in human-derived strains. Additionally, the LEE island was also analyzed at genomic, transcriptional, and functional levels through genomic analysis, quantitative reverse transcription PCR, and HEp-2 cell adherence assays, respectively. The eae transcript levels were variable and associated with eae subtypes. Three different adherence patterns, including localized adherence-like (LAL), diffuse adherence (DA), and detachment (DE), were observed among E. albertii strains. This study demonstrated a high diversity of functional intimin in E. albertii strains isolated from humans, animals, and food. Further in vivo and in vitro studies are warranted to better elucidate the role of intimin or LEE in different genetic backgrounds.

Escherichia albertii isolated from the bloodstream of a patient with liver cirrhosis in China: A case report

A rare case of bacteremia caused by Escherichia albertii, in a 50-year-old male with liver cirrhosis was reported. Clear, colorless, and circular colonies were recovered on blood agar after 24 h of aerobic incubation at 37 °C. The isolate was identified as E. albertii using MALDI-TOF/MS and confirmed by the diagnostic triplex-PCR targeting clpX, lysP, and mdh genes. The administration of piperacillin/tazobactam intravenously (4.5g every 8 hours) for 3 days was effective. This study suggested that specific strains of E. albertii have been implicated in causing extraintestinal infections in humans, similar to extraintestinal pathogenic E. coli (ExPEC). However, a comprehensive understanding of the underlying pathogenic mechanisms requires further exploration.

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