Prevalence of Escherichia albertii in Raccoons (Procyon lotor), Japan

Detection of prolong excretion of Escherichia albertii in stool specimens of a 7-year-old child by a newly developed Eacdt gene-based quantitative real-time PCR method and molecular characterization of the isolates

Escherichia albertii is an emerging zoonotic foodborne pathogen. The clinical significance of this bacterium has increasingly been recognized worldwide. However, diagnostic method has not yet been established and its clinical manifestations are not fully understood. Here, we show that an Eacdt gene-based quantitative real-time PCR (qRT-PCR) developed in this study is 100% specific and sensitive when tested with 39 E. albertii and 36 non-E. albertii strains, respectively. Detection limit of the real-time PCR was 10 colony forming unit (CFU) and 1 pg of genomic DNA per PCR tube. When E. albertii was spiked with 4 × 100-106 CFU per mL to stool of healthy person, detection limit was 4.0 × 103 and 4.0 CFU per mL before and after enrichment culture, respectively. Moreover, the qRT-PCR was able to detect E. albertii in five children out of 246 (2%) but none from 142 adults suffering from gastroenteritis. All five E. albertii strains isolated carried eae and paa genes, however, only one strain harbored stx2f genes. Long-term shedding of stx2f gene-positive E. albertii in a child stool could be detected because of the qRT-PCR developed in this study which might have been missed if only conventional PCR and culture methods were employed. Furthermore, E. albertii isolated from siblings with diarrhea showed clonality by PFGE analysis. Taken together, these data suggest that the Eacdt gene-based qRT-PCR developed for the detection of E. albertii is useful and will assist in determining the real burden and clinical manifestation of E. albertii infections.

An interlaboratory study on the detection method for Escherichia albertii in food using real time PCR assay and selective agars

Escherichia albertii is an emerging enteropathogen. Although E. albertii-specific detection and isolation methods have been developed, their efficiency on food samples have not yet been systematically studied. To establish a series of effective methods for detecting E. albertii in food, an interlaboratory study was conducted in 11 laboratories using enrichment with modified E. coli broth supplemented with cefixime and tellurite (CT-mEC), real-time PCR assay, and plating on four kinds of selective agars. This study focused on the detection efficiency of an E. albertii-specific real-time PCR assay (EA-rtPCR) and plating on deoxycholate hydrogen sulfide lactose agar (DHL), MacConkey agar (MAC), DHL supplemented with rhamnose and xylose (RX-DHL), and MAC supplemented with rhamnose and xylose (RX-MAC). Chicken and bean sprout samples were inoculated with E. albertii either at 17.7 CFU/25 g (low inoculation level) or 88.5 CFU/25 g (high inoculation level), and uninoculated samples were used as controls. The sensitivity of EA-rtPCR was 1.000 for chicken and bean sprout samples inoculated with E. albertii at low and high inoculation levels. The Ct values of bean sprout samples were higher than those of the chicken samples. Analysis of microbial distribution by 16S rRNA gene amplicon sequencing in enriched cultures of bean sprout samples showed that approximately >96 % of the population comprised unidentified genus of family Enterobacteriaceae and genus Acinetobacter in samples which E. albertii was not isolated. The sensitivity of the plating methods for chicken and bean sprout samples inoculated with a high inoculation level of E. albertii was 1.000 and 0.848-0.970, respectively. The sensitivity of the plating methods for chicken and bean sprout samples inoculated with a low inoculation level of E. albertii was 0.939-1.000 and 0.515-0.727, respectively. The E. albertii-positive rate in all colonies isolated in this study was 89-90 % in RX-DHL and RX-MAC, and 64 and 44 % in DHL and MAC, respectively. Therefore, the sensitivity of RX-supplemented agar was higher than that of the agars without these sugars. Using a combination of enrichment in CT-mEC and E. albertii isolation on selective agars supplemented with RX, E. albertii at an inoculation level of over 17.5 CFU/25 g of food was detected with a sensitivity of 1.000 and 0.667-0.727 in chicken and bean sprouts, respectively. Therefore, screening for E. albertii-specific genes using EA-rtPCR followed by isolation with RX-DHL or RX-MAC is an efficient method for E. albertii detection in food.

Growth and Survival of Escherichia albertii in Food and Environmental Water at Various Temperatures

Escherichia albertii is an emerging foodborne pathogen that causes diarrhea. E. albertii has been isolated from various foods, including pork and chicken meat, and environmental waters, such as river water. Although many food poisoning cases have been reported, there have been insufficient analyses of bacterial population behaviors in food and environmental water. In this study, we inoculated 2-5 log CFU of E. albertii into 25 g of pork, chicken meat, Japanese rock oyster, Pacific oyster, and 300 mL of well water and seawater at 4°C, 10°C, 20°C, and 30°C, and analyzed the bacterial population behavior in food and environmental water. After 3 days at 4°C, the population of E. albertii strain EA21 and EA24 in foods maintained approximately 4 log CFU/25 g. After 3 days at 10°C, the population of E. albertii strains in pork and oysters maintained approximately 4 log CFU/25 g, and that in chicken meat increased to approximately 5-6 log CFU/25 g. After 2 days at 20°C, E. albertii strains grew to approximately 6-7 log CFU/25 g in pork and chicken meat, and E. albertii strain EA21 but not EA24 grew to 4.5 log CFU/25 g in Japanese rock oyster, E. albertii strain EA21 but not EA24 slightly grew to 3.1 log CFU/25 g in Pacific oyster. After 1 day at 30°C, E. albertii strains grew to approximately 7-8 log CFU/25 g in chicken meat and pork, grew to approximately 4-6 log CFU/25 g in Japanese rock oyster, and 6-7 log CFU/25 g in Pacific oyster. These results suggest that E. albertii survives without growth below 4°C and grew rapidly at 20°C and 30°C in foods, especially in meat. E. albertii strains did not grow in well water and seawater at 4°C, 10°C, 20°C, and 30°C. The population of E. albertii strains in well water and seawater decreased faster at 30°C than at 4°C, 10°C, and 20°C, suggesting that E. albertii has low viability at 30°C in environmental water.

Seasonality of detection rate of Escherichia albertii in wild raccoons (Procyon lotor) in Osaka, Japan

Escherichia albertii has increasingly been recognized as an important emerging zoonotic enteropathogen. Raccoon is shown to be one of the most vital reservoirs of this pathogen. E. albertii has been detected in 993 (62%) out of 1,606 wild raccoons in Osaka, Japan from 2017 to 2020 by Eacdt-PCR. The detection rate of E. albertii was increased from May to December (winter) and gradually decreased from January to April (spring). Furthermore, we could isolate E. albertii from 30% (196/664) of Eacdt-PCR positive samples and the monthly isolation rate seems to correlate with its detection rate. These data indicate that there is a seasonality regarding the prevalence of E. albertii in wild raccoon being higher in winter and lower in spring.

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.

The genomic epidemiology of Escherichia albertii infecting humans and birds in Great Britain

Escherichia albertii is a recently identified gastrointestinal bacterial pathogen of humans and animals which is typically misidentified as pathotypes of diarrhoeagenic Escherichia coli or Shigella species and is generally only detected during genomic surveillance of other Enterobacteriaceae. The incidence of E. albertii is likely underestimated, and its epidemiology and clinical relevance are poorly characterised. Here, we whole genome sequenced E. albertii isolates from humans (n = 83) and birds (n = 79) isolated in Great Britain between 2000 and 2021 and analysed these alongside a broader public dataset (n = 475) to address these gaps. We found human and avian isolates typically (90%; 148/164) belonged to host-associated monophyletic groups with distinct virulence and antimicrobial resistance profiles. Overlaid patient epidemiological data suggested that human infection was likely related to travel and possibly foodborne transmission. The Shiga toxin encoding stx2f gene was associated with clinical disease (OR = 10.27, 95% CI = 2.98-35.45 p = 0.0002) in finches. Our results suggest that improved future surveillance will further elucidate disease ecology and public and animal health risks associated with E. albertii.

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

Escherichia albertii is an emerging zoonotic foodborne enteropathogen leading to human gastroenteritis outbreaks. Although E. albertii has been isolated from birds which have been considered as the potential reservoirs of this bacterium, its prevalence in migratory birds has rarely been described. In this study, E. albertii in migratory birds from Poyang Lake was investigated and characterized using whole genome sequencing. Eighty-one fecal samples from nine species of migratory birds were collected and 24/81 (29.6%) tested PCR-positive for E. albertii-specific genes. A total of 47 isolates was recovered from 18 out of 24 PCR-positive samples. All isolates carried eae and cdtB genes. These isolates were classified into eight E. albertii O-genotypes (EAOgs) (including three novel EAOgs) and three E. albertii H-genotypes (EAHgs). Whole genome phylogeny separated migratory bird-derived isolates into different lineages, some isolates in this study were phylogenetically closely grouped with poultry-derived or patient-derived strains. Our findings showed that migratory birds may serve as an important reservoir for heterogeneous E. albertii, thereby acting as potential transmission vehicles of E. albertii to humans.

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.

Isolation and characterization of Escherichia albertii from wild and safeguarded animals in Okayama Prefecture and its prefectural borders, Japan

Escherichia albertii has recently been recognized as a zoonotic enteropathogen associated with food poisoning. The reservoirs and transmission routes of this bacterium to humans are still unclear. In this study, we performed a survey of E. albertii in fecal specimens of wild and safeguarded animals in Okayama Prefecture and its prefectural borders, Japan to understand its reservoir in the environment. Forty-two E. albertii were isolated from 10 and 31 droppings of 59 crows and 125 starlings, respectively. Fifty-two E. albertii were isolated from 906 mammal droppings, and out of 52 isolates, origin of 33, 6 and 1 isolates were from martens, foxes, and rabbit, respectively, however, origin of 12 isolates remained unknown. Three E. albertii were isolated from two and one feces of 159 dogs and 76 cats, respectively. Pulsed-filed gel electrophoresis analysis grouped 97 E. albertii strains into 66 pulsotypes including 36 and 30 pulsotypes of isolates from mammals and birds, respectively. E. albertii strains isolated in this study were genetically diverse. Although clonal relationship was not observed between mammal and bird isolates, there were intra- and inter-species relationship in mammalian isolates. All E. albertii strains were positive for eae and Eacdt virulence genes. Furthermore, 20 and 7 strains also carried Eccdt-I and stx2f genes, respectively. Taken together, the results indicate that genetically diverse and potentially virulent E. albertii are distributed among various wild and safeguarded animals in Okayama Prefecture, and the animals could also be reservoirs of E. albertii.

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.

Isolation and characterization of Escherichia albertii originated from the broiler farms in Mississippi and Alabama

Escherichia albertii is an emerging foodborne enteropathogen with increasing outbreaks worldwide, particularly in Japan recently. However, major features of this zoonotic pathogen, such as prevalence, virulence, and antibiotic resistance (AR), still remain under characterized. In a recent pilot study, we reported isolation of E. albertii from a chicken farm in Tennessee, suggesting chicken is an important reservoir for E. albertii. In this large-scale study, we examined prevalence of E. albertii in 9 farms in Mississippi and Alabama. Of a total of 270 cloacal swabs (30 per farm), 43 were PCR positive and 12 E. albertii strains were isolated with different isolation rates in individual farms ranging from 0 to 23.3 %. Both PFGE and whole genome analysis showed the E. albertii from different farms were phylogenetically distant, but those from the same farm displayed clonal relationships. Consistently, the antibiogram, AR gene profiles, and plasmid replicon types were similar across the strains in the same farm. Notably, 9 of the 12 E. albertii strains displayed multidrug resistance; one strain was even resistant to imipenem, a clinically important carbapenem antibiotic. In addition, comparative genomics analysis showed that two chicken E. albertii clusters displayed very close evolutionary relationships and similar virulence gene profiles to human E. albertii strains. In vitro growth assay demonstrated that the anti-enterobactin antibodies could dramatically inhibit the growth of two representative chicken E. albertii, supporting the feasibility of the novel enterobactin-based immune intervention for controlling this emerging pathogen. Taken together, the findings from this study further indicated chickens as an important reservoir for E. albertii in the U.S., highlighting the need to prevent and control E. albertii in poultry production.

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

Molecular Study of Escherichia albertii in Pediatric Urinary Tract Infections

Background:

There are insufficient data about the presence of E. albertii as a causative organism in urinary tract infection in pediatric patients. Objective: The present study aimed to detect E. albertii by polymerase chain reaction (PCR) for detection of uidA, mdh, and lysP genes among isolated E.coli from children with urinary tract infection.

Methods:

The present study was a cross-sectional retrograde study which was carried out on 100 isolates of phenotypically confirmed E.coli detected in urine samples of children suffering from urinary tract infection. The isolates were subjected to molecular identification by PCR for uidA, mdh, and lysP genes.

Results:

E. albertii was identified by PCR in 7% of the isolates and E.coli was identified in 93% of the isolates. Two mdh and lysP genes were detected for E. albertii and the uidA gene for E. coli. E. albertii isolates had marked resistance to gentamicin (71.4%), followed by resistance to ciprofloxacin (57.1%), meropenem and imipenem (42.9% each) and ESBL activity by double discs method was reported in 57.1% of the isolates. However, none of the isolates had shown resistance to nalidixic acid and only one isolate had resistance to norfloxacin. There was a statistically insignificant difference between resistance to the used antibiotics such as aztreonam (P=0.083), ampicillin/clavulanate (P=0.5), ciprofloxacin (P=0.69), gentamicin (P=0.3) and ceftazidime (P=1.00).

Conclusion:

The present study highlights the emergence of E. albertii as a pathogen associated with urinary tract infections in children. There is marked antibiotic resistance of this pathogen, especially toward extended spectrum beta-lactams antibiotics. The identification method depends mainly on genetic studies. Further longitudinal studies with large number of patients are required to verify the accurate prevalence of this bacterium.

[Molecular epidemiology of Escherichia albertii, emerging zoonotic enteropathogen]

Escherichia albertii is an emerging zoonotic enteric pathogen, closely related to E. coli. Several foodborne outbreaks caused by E. albertii accounting for >100 patients have recently occurred in Japan. This bacterium carries eae gene, similar to enteropathogenic E. coli. Some of them harbor Shiga toxin 2 (stx2a, stx2f) genes, primary virulence factor of enterohemorrhagic E. coli (EHEC), suggesting that the Stx2 producers could cause severe diseases such as HUS in humans. However, due to lack of the knowledges about its bacteriological characteristics and of the diagnostic methods, E. albertii-related infections might have been underestimated, and the infection sources and routes have not yet been understood. We had continuously performed molecular epidemiological studies targeting for cytolethal distending toxin-producing E. coli, and unexpectedly found that cdt-II gene-positive isolates were not E. coli but E. albertii. This finding led us to initiate research more focusing on E. albertii. We have constructed simple, efficient and reliable methods for the detection, isolation and identification of this bacterium by developing an E. albertii-specific PCR assay targeting Eacdt genes and E. albertii-selective isolation medium named XRM-MacConkey agar. We have also identified raccoons as a potential natural reservoir of E. albertii through wildlife survey using these methods. Here, I describe what I have studied with my colleagues.

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

The Changing Face of the Family Enterobacteriaceae (Order: "Enterobacterales"): New Members, Taxonomic Issues, Geographic Expansion, and New Diseases and Disease Syndromes

The family Enterobacteriaceae has undergone significant morphogenetic changes in its more than 85-year history, particularly during the past 2 decades (2000 to 2020). The development and introduction of new and novel molecular methods coupled with innovative laboratory techniques have led to many advances. We now know that the global range of enterobacteria is much more expansive than previously recognized, as they play important roles in the environment in vegetative processes and through widespread environmental distribution through insect vectors. In humans, many new species have been described, some associated with specific disease processes. Some established species are now observed in new infectious disease settings and syndromes. The results of molecular taxonomic and phylogenetics studies suggest that the current family Enterobacteriaceae should possibly be divided into seven or more separate families. The logarithmic explosion in the number of enterobacterial species described brings into question the relevancy, need, and mechanisms to potentially identify these taxa. This review covers the progression, transformation, and morphogenesis of the family from the seminal Centers for Disease Control and Prevention publication (J. J. Farmer III, B. R. Davis, F. W. Hickman-Brenner, A. McWhorter, et al., J Clin Microbiol 21:46-76, 1985, https://doi.org/10.1128/JCM.21.1.46-76.1985) to the present.

Isolation and characterization of Escherichia albertii in poultry at the pre-harvest level

Escherichia albertii, often misidentified as Escherichia coli, has become an emerging foodborne human enteric pathogen. However, the prevalence and major animal reservoirs of this significant pathogen are still not clear. Here, we performed comprehensive microbiological, molecular, comparative genomics and animal studies to understand the status and features of E. albertii in the US domestic and food animals. Although no E. albertii was identified in a total of 1,022 diverse E. coli strains isolated from pets and food animals in a retrospective screening, in a pilot study, E. albertii was successfully isolated from a broiler farm (6 out of 20 chickens). The chicken E. albertii isolates showed clonal relationship as indicated by both pulsed-field gel electrophoresis (PFGE) and whole-genome sequence analysis. The isolated chicken E. albertii displayed multidrug resistance; all the resistance determinants including the extended-spectrum beta-lactamase gene, carried by plasmids, could be conjugatively transferred to E. coli, which was further confirmed by S1-PFGE and Southern hybridization. Whole-genome sequence-based phylogenetic analysis showed the chicken E. albertii strains were phylogenetically close to those of human origins. Challenge experiment demonstrated that the E. albertii strains isolated from human and wild bird could successfully colonize in the chicken intestine. Together, this study, for the first time, reported the isolation of E. albertii in poultry at the pre-hrvest level. The findings from multi-tier characterization of the chicken E. albertii strains indicated the importance of chickens as a reservoir for E. albertii. A large scale of E. albertii survey in poultry production at the pre-harvest level is highly warranted in the future.

Accurate identification of Escherichia albertii by matrix-assisted laser desorption ionization-time of flight mass spectrometry

A specific identification protocol for Escherichia albertii by using a MALDI-TOF/MS method was developed. For this purpose, a novel database was established which can differentiate E. albertii from E. coli by combining the mass spectra obtained from 58 E. albertii and 36 E. coli strains.