Detection of Escherichia albertii from chicken meat and giblets

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.

Development of a novel modified selective medium cefixime-tellurite-phosphate-xylose-rhamnose MacConkey agar for isolation of Escherichia albertii and its evaluation with food samples

Since cefixime and tellurite are known to inhibit most bacteria belonging to Enterobacterales, we found that addition of tellurite inhibited E. albertii growth in Luria Bertani broth but not in tryptic soy broth (TSB), and addition of phosphate and soy peptone enhanced E. albertii growth in TSB in presence of tellurite. Subsequently, to find the positive factor present in TSB, E. albertii growth was examined in tryptone, soy peptone, glucose, or phosphate deficient tryptic soy agar plates. Phosphate, soy peptone, and/or glucose deficiency indeed decreased E. albertii growth. However, none of the substances are specifically present in xylose-rhamnose-melibiose (XRM)-MacConkey agar and thus, not affecting E. albertii growth. Altogether, a novel E. albertii selective differential medium, XRM-MacConkey medium containing cefixime (C), tellurite (T), phosphate (P), and soy peptone (S) (named CT-PS-XR-MacConkey medium), which differentiate E. albertii (colorless) from E. coli (red) by colony color, has been developed. The CT-PS-XR-MacConkey agar was evaluated with 156 bacterial strains including 65 E. albertii. While all E. albertii strains grew as colorless colonies, 54 strains of 9 different genera belonging to 19 different species were unable to grow on this medium. However, rest of these bacterial strains grew either as colorless or as red colonies. Furthermore, spiking experiments using chicken meat as food samples showed that the CT-PS-XR-MacConkey medium is highly selective for E. albertii than XRM-MacConkey agar. Altogether, the results suggest that the CT-PS-XR-MacConkey agar is indeed a useful selective medium for isolation of E. albertii from food samples.

Isolation and Detection of the Emerging Pathogen Escherichia albertii in Clinical Stool Samples and the Potential Transmission by Meat Samples in Retail

The significance of Escherichia albertii as a foodborne pathogen is increasingly acknowledged, but the assessment of its occurrence and transmission remains challenging due to the lack of validation of selective isolation, detection, and identification methods. The aim of the present study was to examine its presence on various meat samples at the retail level in order to assess a potential foodborne transmission and its occurrence in clinical stool samples. First, the evaluation and selection of a selective enrichment broth and isolation medium, combined with an optimized identification by MALDI-TOF MS, as well as a suitable DNA extraction method and a PCR-based detection strategy were developed. After the evaluation of existing isolation strategies and the formulation of an adapted enrichment and isolation medium, 100% isolation specificity was not achieved. An identity confirmation of suspected colonies remains necessary. A total of 292 samples, including 45 beef fillet, 51 minced beef, 50 pork fillet, 30 minced pork, 30 chicken carcass, 51 chicken fillet, and 35 minced chicken samples were examined. Samples were all collected at the retail level, including supermarkets and local butcheries. Escherichia albertii was isolated from two chicken fillets (3.9%) and additionally detected in one minced chicken (4.5%) and two other chicken fillet (4.5%) samples by a PCR assay. All beef and pork samples tested negative for its presence, but transmission through these meat types cannot be excluded, as it potentially correlates with the level of fecal contamination that was significantly higher on poultry products. With other hygienic conditions and processing steps applied, the presence of E. albertii on food can therefore differ in other parts of the world. Escherichia albertii was present in 0.4% of the 2419 clinical stool samples examined. The future development of a chromogenic isolation medium, as well as further extensive epidemiologic approaches and a genomic comparison of human, food, and animal isolates, could enhance the assessment of the emerging pathogen status and its potential as a foodborne hazard.

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.

Conditional expression of flagellar motility, curli fimbriae, and biofilms in Shiga toxin- producing Escherichia albertii

Escherichia albertii is an emerging foodborne pathogen. We previously reported that some avian Shiga toxin-producing E. albertii strains exhibited higher or comparable cytotoxicity in Vero-d2EGFP cells with several enterohemorrhagic E. coli (EHEC) outbreak strains. To better understand the environmental persistence of this pathogen, comparative genomics and phenotypic assays were applied to assess adhesion capability, motility, and biofilm formation in E. albertii. Among the 108 adherence-related genes, those involved in biogenesis of curli fimbriae, hemorrhagic E. coli pilus, type 1 fimbriae, and Sfm fimbriae were conserved in E. albertii. All 20 E. albertii strains carried a complete set of primary flagellar genes that were organized into four gene clusters, while five strains possessed genes related to the secondary flagella, also known as lateral flagella. Compared to EHEC strain EDL933, the eight chemotaxis genes located within the primary flagellar gene clusters were deleted in E. albertii. Additional deletion of motility genes flhABCD and motBC was identified in several E. albertii strains. Swimming motility was detected in three strains when grown in LB medium, however, when grown in 5% TSB or in the pond water-supplemented with 10% pigeon droppings, an additional four strains became motile. Although all E. albertii strains carried curli genes, curli fimbriae were detected only in four, eight, and nine strains following 24, 48, and 120 h incubation, respectively. Type 1 fimbriae were undetectable in any of the strains grown at 37°C or 28°C. Strong biofilms were detected in strains that produced curli fimbriae and in a chicken isolate that was curli fimbriae negative but carried genes encoding adhesive fimbriae K88, a signature of enterotoxigenic E. coli strains causing neonatal diarrhea in piglets. In all phenotypic traits examined, no correlation was revealed between the strains isolated from different sources, or between the strains with and without Shiga toxin genes. The phenotypic variations could not be explained solely by the genetic diversity or the difference in adherence genes repertoire, implying complex regulation in expression of various adhesins. Strains that exhibited a high level of cytotoxicity and were also proficient in biofilm production, may have potential to emerge into high-risk pathogens.

Escherichia albertii as a Potential Enteropathogen in the Light of Epidemiological and Genomic Studies

Escherichia albertii is a new enteropathogen of humans and animals. The aim of the study was to assess the prevalence and pathogenicity of E. albertii strains isolated in northeastern Poland using epidemiological and genomic studies. In 2015-2018, a total of 1154 fecal samples from children and adults, 497 bird droppings, 212 food samples, 92 water samples, and 500 lactose-negative E. coli strains were tested. A total of 42 E. albertii strains were isolated. The PCR method was suitable for their rapid identification. In total, 33.3% of E. albertii isolates were resistant to one antibiotic, and 16.7% to two. Isolates were sensitive to cefepime, imipenem, levofloxacin, gentamicin, trimethoprim/sulfamethoxazole, and did not produce ESBL β-lactamases. High genetic variability of E. albertii has been demonstrated. In the PFGE method, 90.5% of the strains had distinct pulsotypes. In MLST typing, 85.7% of strains were assigned distinct sequence types (STs), of which 64% were novel ST types. Cytolethal distending toxin (CDT) and Paa toxin genes were found in 100% of E. albertii isolates. Genes encoding toxins, IbeA, CdtB type 2, Tsh and Shiga (Stx2f), were found in 26.2%, 9.7%, 1.7%, and 0.4% of E. albertii isolates, respectively. The chromosome size of the tested strains ranged from 4,573,338 to 5,141,010 bp (average 4,784,003 bp), and at least one plasmid was present in all strains. The study contributes to a more accurate assessment of the genetic diversity of E. albertii and the potential threat it poses to public health.

Occurrence and Characteristics of Escherichia albertii in Wild Birds and Poultry Flocks in Switzerland

Escherichia albertii, a zoonotic pathogen, has sporadically been associated with infectious diarrhea in humans. Poultry and wild birds are considered potential reservoirs. We assessed the occurrence of E. albertii in 280 fecal samples from wild birds (n = 130) and pooled fecal samples collected at slaughterhouse level from poultry flocks (n = 150) in Switzerland. Using an E. albertii-specific PCR targeting the Eacdt gene, 23.8% (31/130) of the samples from wild birds, but not from the pooled poultry fecal samples, tested positive for Eacdt. The positive samples originated from 11 bird species belonging to eight families. Strain isolation was attempted on the PCR-positive samples by subculturing the broth cultures onto xylose–MacConkey plates. Isolation was possible on 12 of the 31 Eacdt-PCR-positive samples. Whole-genome sequencing revealed that the strains belonged to nine distinct sequence types, with ST13420 and ST5967 being represented by two and three isolates, respectively. All strains harbored the eae gene, while two strains were also positive for stx2f. Our study thus shows that E. albertii is present in the Swiss wild bird population, which can potentially act as a source of this pathogen to humans, other animals, and the environment.

Microbiology and Epidemiology of Escherichia albertii—An Emerging Elusive Foodborne Pathogen

Escherichia albertii, a close relative of E. coli, is an emerging zoonotic foodborne pathogen associated with watery diarrhea mainly in children and immunocompromised individuals. E. albertii was initially classified as eae-positive Hafnia alvei, however, as more genetic and biochemical information became available it was reassigned to its current novel taxonomy. Its infections are common under conditions of poor hygiene with confirmed transmission via contaminated water and food, mainly poultry-based products. This pathogen has been isolated from various domestic and wild animals, with most isolates being derived from birds, implying that birds among other wild animals might act as its reservoir. Due to the absence of standardized isolation and identification protocols, E. albertii can be misidentified as other Enterobacteriaceae. Exploiting phenotypes such as its inability to ferment rhamnose and xylose and PCR assays targeting E. albertii-specific genes such as the cytolethal distending toxin and the DNA-binding transcriptional activator of cysteine biosynthesis encoding genes can be used to accurately identify this pathogen. Several gaps exist in our knowledge of E. albertii and need to be bridged. A deeper understanding of E. albertii epidemiology and physiology is required to allow the development of effective measures to control its transmission and infections. Overall, current data suggest that E. albertii might play a more significant role in global infectious diarrhea cases than previously assumed and is often overlooked or misidentified. Therefore, simple, and efficient diagnostic tools that cover E. albertii biodiversity are required for effective isolation and identification of this elusive agent of diarrhea.

Detection of Escherichia albertii in Retail Oysters

ABSTRACT

Escherichia albertii is an emerging foodborne pathogen. Owing to its distribution in river water, it is important to determine the presence of E. albertii in aquaculture-related foods. In this study, we investigated the distribution of E. albertii in retail oyster samples. A total of 427 raw oyster samples (385 Pacific oysters and 42 Japanese rock oysters) were enriched in modified Escherichia coli broth (mEC) or mEC supplemented with novobiocin (NmEC) at 42°C. The cultures were used for E. albertii-specific nested PCR assay, as well as for E. albertii isolation using deoxycholate hydrogen sulfide lactose agar (DHL), DHL supplemented with rhamnose and xylose, and MacConkey agar supplemented with rhamnose and xylose. The population of E. albertii in nested PCR-positive samples was determined using the most-probable-number (MPN) method. E. albertii isolates were subjected to biochemical and genetic characterization. E. albertii was detected in 5 (1.6%) of 315 Pacific oyster samples (one piece each), 2 (2.9%) of 70 Pacific oyster samples (25 g each), and 2 (4.8%) of 42 Japanese rock oyster samples procured from four geographically distinct regions. A total of 64 E. albertii strains were isolated from eight of the nine nested PCR assay-positive oyster samples, and the MPN value was under the detection limit (<3 MPN/10 g). A specific season or month for detecting E. albertii was not observed in this study, suggesting that the pathogen is present in seawater. All the E. albertii isolates, except one, were positive for the virulence factor eae, indicating that these isolates have the potential to infect humans.

HIGHLIGHTS

[Prevalence of Foodborne Pathogens in Retail Meat in Saitama, Japan]

We investigated the prevalence of Campylobacter jejuni, Campylobacter coli, Salmonella, enterohemorrhagic Escherichia coli, enterotoxigenic Escherichia coli, Yersinia enterocolitica, and Escherichia albertii in domestic chicken and pork sold at retail stores in Saitama Prefecture, Japan. Campylobacter was detected in 35.7% (60/168) of chicken samples and 7.3% (14/190) of pork samples. C. jejuni and C. coli were predominant in chicken and pork, respectively. Salmonella was found in 58.1% (100/172) of chicken samples and 19.9% (41/206) of pork samples. Moreover, Salmonella Schwarzengrund was the major serovar observed in chicken isolates, whereas S. Typhimurium monophasic variant was in pork isolates. Furthermore, ETEC was found in 0.6% (1/160) of chicken samples and 2.4% (5/206) of pork samples. Y. enterocolitica was absent from all (83/83) chicken samples but was present in 9.3% (18/193) of pork samples, with a prevalence in pork tongues as high as 21.0% (13/62 samples). However, EHEC and E. albertii were not detected in our study. Therefore, the results of this study indicate that chicken was highly contaminated with Campylobacter sp. and Salmonella, and pork was with Y. enterocolitica serotype O3, Campylobacter sp., Salmonella, and ETEC.

Proposal of a novel selective enrichment broth, NCT-mTSB, for isolation of Escherichia albertii from poultry samples

AIMS

Escherichia albertii is an emerging diarrheagenic pathogen causing food- and water-borne infection in humans. However, no selective enrichment broths for E. albertii have ever been reported. In this study, we tested several basal media, selective supplements and culture conditions which enabled selective enrichment of E. albertii.

METHODS AND RESULTS

We developed a selective enrichment broth, novobiocin-cefixime-tellurite supplemented modified tryptic soy broth (NCT-mTSB). NCT-mTSB supported the growth of 22 E. albertii strains, while inhibited growth of other Enterobacteriaceae at 37°C, except for Escherichia coli and Shigella spp. Enrichment of E. albertii was improved further by growth at 44°C, a temperature that suppresses growth of several strains of E. coli/Shigella. Combined use of NCT-mTSB with XR-DH-agar, xylose-rhamnose supplemented deoxycholate hydrogen sulphide agar, enabled isolation of E. albertii when at least 1 CFU of the bacterium was present per gram of chicken meat. This level of enrichment was superior to those obtained using buffered peptone water, modified-EC broth, or mTSB (with novobiocin).

CONCLUSIONS

Novobiocin-cefixime-tellurite supplemented modified tryptic soy broth enabled effective enrichment of E. albertii from poultry samples and was helpful for isolation of this bacterium.

SIGNIFICANCE AND IMPACT OF STUDY

To our knowledge, this is the first report of selective enrichment of E. albertii from poultry samples.

Detection, isolation and molecular characterization of Escherichia albertii in wild birds in West Japan

Escherichia albertii is an emerging zoonotic foodborne pathogen. Several outbreaks of E. albertii have occurred particularly in Japan. Although birds have been considered as one of the most important reservoirs of this bacterium, information regarding the prevalence in birds is still scanty. We performed a survey of E. albertii in wild birds in Japan, and examined characteristics of the isolates. E. albertii specific gene was detected in 5 cloacal swabs out of 156 birds by PCR. Four E. albertii were isolated from a swallow with 2 different E. albertii strains and 2 pigeons in a flock by XRM-MacConkey agar. These isolates were assigned to biogroup 3, shown no resistance to any antimicrobials tested, and classified into 2 EAO-genotypes (EAOg2 and EAOg33) and untypable. Similar to clinical E. albertii strains, these isolates carried virulence genes including eae (n=4), paa (n=4), Eccdt-I (n=2) and stx2f (n=1) in addition to Eacdt. Interestingly, stx2f genes in a strain were located on an inducible bacteriophage, which can confer the ability to produce Stx2f to E. coli. In conclusion, Japanese wild birds carried E. albertii at the similar levels to the reported prevalence in birds. These isolates may have a potential to cause gastroenteritis in humans.

Evaluating Methods for Detecting Escherichia albertii in Chicken Meat

ABSTRACT

Escherichia albertii is an emerging foodborne pathogen. The source of the E. albertii infection in most foodborne outbreaks is unknown because E. albertii is difficult to isolate from suspected food or water. E. albertii has a broad host range among birds and can be isolated from chicken meat. In this study, PCR assay, enrichment, and isolation conditions for detecting E. albertii in chicken meat were evaluated. The growth of 47 E. albertii strains isolated in Japan between 1994 and 2018 and a type strain was evaluated in modified EC broth (mEC) and mEC supplemented with novobiocin (NmEC) and on media containing carbohydrates. The enzyme used for the nested PCR, the enrichment conditions, the most-probable-number (MPN) method, and agar media were also evaluated with chicken meat. To distinguish E. albertii from presumptive non-E. albertii bacteria, desoxycholate hydrogen sulfide lactose agar (DHL), MacConkey agar (MAC), and these agars supplemented with rhamnose and xylose (RX-DHL and RX-MAC, respectively) were used. All E. albertii strains grew in mEC and NmEC at both 36 and 42°C and did not utilize rhamnose, sucrose, or xylose. Both the first and nested PCRs with TaKaRa Ex Taq, which was 10 to 100 times more active than the other enzymes, produced positive results in enrichment culture of 25 g of chicken meat inoculated with >20 CFU of E. albertii and incubated in mEC and NmEC at 42°C for 22 ± 2 h. Thus, the first PCR was sensitive enough to detect E. albertii in chicken meat. The MPN values in mEC and NmEC were 0.5- and 2.3-fold higher than the original inoculated bacterial levels, respectively. E. albertii in chicken meat was more efficiently isolated with enrichment in NmEC (70.1 to 100%) and plating onto RX-DHL (85.4%) and RX-MAC (100%) compared with enrichment in mEC (53.5 to 83.3%) and plating onto DHL (70.1%) and MAC (92.4%). Thus, optimized conditions for the surveillance of E. albertii contamination in food and investigations of E. albertii outbreaks, including the infectious dose, were clarified.

HIGHLIGHTS

Isolation and Identification of Escherichia albertii in Broiler Chickens From Kermanshah

Background: F Escherichia albertii is generally recognized as a human pathogen with a limited number of strains. It has also been identified as a cause of mortality among birds. The clinical significance and prevalence of E. albertii are somewhat unknown. Objectives: The aim of the present study was to isolate and identify E. albertii as a causative agent of respiratory infections in broilers. Materials and Methods: During a three-month period (Winter 2018), 200 samples of the air sacs of 100 chickens with suspected colibacillosis were collected. Routine biochemical tests were performed and suspected isolates of E. albertii were selected for polymerase chain reaction (PCR). Results: A total of 68 suspected samples of E. albertii and Escherichia coli were isolated. Further, E. coli was detected in all the suspected samples using species-specific sequences of E. coli (uidA) and E. albertii (mdh and lysP). Conclusion: Escherichia albertii was not identified as a cause of respiratory infection in broilers.

Escherichia albertii Pathogenesis

Escherichia albertii is an emerging enteropathogen of humans and many avian species. This bacterium is a close relative of Escherichia coli and has been frequently misidentified as enteropathogenic or enterohemorrhagic E. coli due to their similarity in phenotypic and genetic features, such as various biochemical properties and the possession of a type III secretion system encoded by the locus of enterocyte effacement. This pathogen causes outbreaks of gastroenteritis, and some strains produce Shiga toxin. Although many genetic and phenotypic studies have been published and the genome sequences of more than 200 E. albertii strains are now available, the clinical significance of this species is not yet fully understood. The apparent zoonotic nature of the disease requires a deeper understanding of the transmission routes and mechanisms of E. albertii to develop effective measures to control its transmission and infection. Here, we review the current knowledge of the phylogenic relationship of E. albertii with other Escherichia species and the biochemical and genetic properties of E. albertii, with particular emphasis on the repertoire of virulence factors and the mechanisms of pathogenicity, and we hope this provides a basis for future studies of this important emerging enteropathogen.

Non-biogroup 1 or 2 Strains of the Emerging Zoonotic Pathogen Escherichia albertii, Their Proposed Assignment to Biogroup 3, and Their Commonly Detected Characteristics

Escherichia albertii, a zoonotic enteropathogen, is responsible for outbreaks of disease in humans. Identifying strains of E. albertii by phenotypic characterization tests is difficult because of its poorly defined properties. Screening its phenotypic characteristics is, nevertheless, a necessary prerequisite for further genetic analysis of its properties, and species-specific polymerase chain reaction (PCR) analysis can be used to type the pathogen. While two E. albertii biogroups (1 and 2) have been described, strains with characteristics divergent from both biogroups have been reported worldwide. The aim of the present study was to evaluate the characteristics of non-biogroup 1 or 2 strains, and discern the characteristics common to all of the E. albertii strains from this study. Altogether, 107/414 field isolates were selected for examination based on pulsed-field gel electrophoresis analysis. The 107 strains were isolated from 92 sources, including humans and pigeon feces, other wild birds, and retail chicken livers. All strains were then examined using various culture-based, biochemical (API 50CHE tests, API Zym test, and others) and molecular (virulence gene screening, multi-locus sequence analysis) testing methods. Our results revealed that all field strains (n = 107) showed non-biogroup 1 or 2 characteristics, with multiple sequence differences. Variations in indole production and the lysine decarboxylase activity profiles among the isolates made identification of E. albertii very difficult. Therefore, we propose that non-biogroup 1 or 2 of E. albertii should be assigned to biogroup 3 to make screening of them easier in public health and clinical laboratory settings. Clearly, having group criteria for indole-negative/lysine-positive, indole-positive/lysine-negative, and indole-positive/lysine-positive E. albertii biogroups 1, 2, and 3 strains, respectively, should provide for more accurate identification of E. albertii isolates. Based on our findings, we recommend that isolates displaying phenotype mobility-negativity (sulfide-indole-motility medium, 37°C), hydrogen sulfide production-negativity (triple sugar iron medium), acid production-negativity from xylose, negative β-glucuronidase activity properties, and showing indole production and lysine decarboxylase activity profiles in accordance with one of the three biogroups, should be further assessed using an E. albertii-specific PCR assay.

The Evasive Enemy: Insights into the Virulence and Epidemiology of the Emerging Attaching and Effacing Pathogen Escherichia albertii

The diarrheic attaching and effacing (A/E) pathogen Escherichia albertii was first isolated from infants in Bangladesh in 1991, although the bacterium was initially classified as Hafnia alvei Subsequent genetic and biochemical interrogation of these isolates raised concerns about their initial taxonomic placement. It was not until 2003 that these isolates were reassigned to the novel taxon Escherichia albertii because they were genetically more closely related to E. coli, although they had diverged sufficiently to warrant a novel species name. Unfortunately, new isolates continue to be mistyped as enteropathogenic E. coli (EPEC) or enterohemorrhagic E. coli (EHEC) owing to shared traits, most notably the ability to form A/E lesions. Consequently, E. albertii remains an underappreciated A/E pathogen, despite multiple reports demonstrating that many provisional EPEC and EHEC isolates incriminated in disease outbreaks are actually E. albertii Metagenomic studies on dozens of E. albertii isolates reveal a genetic architecture that boasts an arsenal of candidate virulence factors to rival that of its better-characterized cousins, EPEC and EHEC. Beyond these computational comparisons, studies addressing the regulation, structure, function, and mechanism of action of its repertoire of virulence factors are lacking. Thus, the paucity of knowledge about the epidemiology, virulence, and antibiotic resistance of E. albertii, coupled with its misclassification and its ability to develop multidrug resistance in a single step, highlights the challenges in combating this emerging pathogen. This review seeks to synthesize our current but incomplete understanding of the biology of E. albertii.

Multidrug-Resistant Escherichia albertii: Co-occurrence of β-Lactamase and MCR-1 Encoding Genes

Escherichia albertii is an emerging member of the Enterobacteriaceae causing human and animal enteric infections. Antimicrobial resistance among enteropathogens has been reported to be increasing in the past years. The purpose of this study was to investigate antibiotic resistance and resistance genes in E. albertii isolated from Zigong city, Sichuan province, China. The susceptibility to 21 antimicrobial agents was determined by Kirby-Bauer disk diffusion method. The highest prevalence was tetracycline resistance with a rate of 62.7%, followed by resistance to nalidixic acid and streptomycin with a rate of 56.9 and 51.0%, respectively. All isolates were sensitive or intermediate susceptible to imipenem, meropenem, amoxicillin-clavulanic acid, and levofloxacin. Among 51 E. albertii isolates, 15 were extended-spectrum β-lactamase-producing as confirmed by the double disk test. The main β-lactamase gene groups, i.e., blaTEM, blaSHV, and blaCTX-M, were detected in17, 20, and 22 isolates, respectively. Furthermore, four colistin-resistant isolates with minimum inhibitory concentrations of 8 mg/L were identified. The colistin-resistant isolates all harbored mcr-1 and blaCTX-M-55. Genome sequencing showed that E. albertii strain SP140150 carried mcr-1 and blaCTX-M-55 in two different plasmids. This study provided significant information regarding antibiotic resistance profiles and identified the co-occurrence of β-lactamase and MCR-1 encoding genes in E. albertii isolates.

Characterization of four Escherichia albertii isolates collected from animals living in Antarctica and Patagonia

Escherichia albertii is a recently discovered species with a limited number of well characterized strains. The aim of this study was to characterize four of the E. albertii strains, which were among 41 identified Escherichia strains isolated from the feces of living animals on James Ross Island, Antarctica, and Isla Magdalena, Patagonia. Sequencing of 16S rDNA, automated ribotyping, and rep-PCR were used to identify the four E. albertii isolates. Phylogenetic analyses based on multi-locus sequence typing showed these isolates to be genetically most similar to the members of E. albertii phylogroup G3. These isolates encoded several virulence factors including those, which are characteristic of E. albertii (cytolethal distending toxin and intimin) as well as bacteriocin determinants that typically have a very low prevalence in E. coli strains (D, E7). Moreover, E. albertii protein extracts caused cell cycle arrest in human cell line A375, probably because of cytolethal distending toxin activity.

Prevalence of eae-positive, lactose non-fermenting Escherichia albertii from retail raw meat in China

Escherichia albertii is a newly emerging enteric pathogen that has been associated with gastroenteritis in humans. Recently, E. albertii has also been detected in healthy and sick birds, animals, chicken meat and water. In the present study, the prevalence and characteristics of the eae-positive, lactose non-fermenting E. albertii strains in retail raw meat in China were evaluated. Thirty isolates of such strains of E. albertii were identified from 446 (6·73%) samples, including duck intestines (21·43%, 6/28), duck meat (9·52%, 2/21), chicken intestines (8·99%, 17/189), chicken meat (5·66%, 3/53), mutton meat (4·55%, 1/22) and pork meat (2·44%, 1/41). None was isolated from 92 samples of raw beef meat. Strains were identified as E. albertii by phenotypic properties, diagnostic PCR, sequence analysis of the 16S rRNA gene, and housekeeping genes. Five intimin subtypes were harboured by these strains. All strains possessed the II/III/V subtype group of the cdtB gene, with two strains carrying another copy of the I/IV subtype group. Pulsed-field gel electrophoresis showed high genetic diversity of E. albertii in raw meats. Our findings indicate that E. albertii can contaminate various raw meats, posing a potential threat to public health.