ABSTRACT
Escherichia albertii is an emerging zoonotic enteropathogen which mainly causes infectious diarrhea. Since the discovery and naming of Escherichia albertii, it was found to be responsible for several outbreaks of foodborne gastroenteritis and widely distributed in avian and wild animals. Due to the lack of specific identification system, the global Escherichia albertii infections might be underestimated. Though avian has been considered as the important reservoir of Escherichia albertii, its role in disease transmission remains unclear. This study reviewed the biochemical properties, genomic characteristics, isolation and identification methods of Escherichia albertii, and its prevalence in human, host animals and food. The risk of Escherichia albertii infection and future perspectives in this field were also discussed.
ABSTRACT
Objective:To understand the molecular characteristics of Escherichia coli producing Shiga toxin 2e subtype isolated from different sources in China. Methods:Three human-derived, 13 animal-derived and eight food-derived stx2e-positive Escherichia coli strains which were isolated during 2012 to 2018 were analyzed by antimicrobial susceptibility testing and whole genome sequencing. The stx subtype, serotype, multi-locus sequence type, virulence genes and antimicrobial resistance genes of each strain were determined by whole genome sequences. The phylogenetic relationship and genetic composition of Shiga-toxin prophage were explored. Results:Twenty-four stx2e-STEC strains were typed into 19 O∶H serotypes and 19 sequence types (STs). Each strain carried at least one kind of antimicrobial resistance gene and 19 out of 24 strains were resistant to at least one kind of antimicrobials. Three human-derived strains were heterogenous in serotypes and STs, but there were several animal and food-derived strains shared the same serotype or ST with human strains and showed close relationship in the phylogenetic analysis. The sequences of stx2e among all strains were highly conserved (similarity >99.7%), but there were significant differences in the size and the gene composition of Shiga toxin prophage genome. Conclusions:This is report about the characteristics of rare human-derived Stx2e-STEC strains in China. Comparing human isolates with animal-and food-derived strains, it indicates that Stx2e-STEC strains are highly genetic diversity and have the potential to infect humans.
ABSTRACT
Objective:To investigate the prevalence and molecular characteristics of Escherichia coli ( E. coli) producing a novel Shiga toxin 2k subtype in goat in Lanling county, Shandong province. Methods:In November 2019, 512 goat fecal samples were collected from different households in Lanling county, Shandong province. After enriched with EC broth, stx-positive samples were detected by PCR and inoculated in CHROMagar? ECC agar and CHROMagar? STEC agar. The whole genomes of stx-positive strains were sequenced. Based on the genomic senquences, the stx subtype, serotype, multi-locus sequence type and virulence genes of each strain were analyzed. Results:Eighty-six strains of Shiga toxin-producing E. coli (STEC) were isolated from 512 goat fecal samples. Five stx subtypes were identified and 37 strains were positive for stx2k. The 86 STEC strains belonged to 20 O∶H serotypes and 18 different sequence types (STs). Conclusions:STEC strains circulating in goats in Lanling county, Shandong province were heterogeneous in stx subtypes, serotypes and virulence gene profiles, and a certain proportion of strains producing a novel Shiga toxin 2k subtype were detected.
ABSTRACT
Shiga toxin (Stx), which can be divided into Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2), is an important virulence factor of Shigella spp. and certain strains of Escherichia coli. Stx, enco-ded by λ-like phage, blocks protein synthesis through removal of an adenine residue from the 28S rRNA. Stx can also induce apoptosis through multiple pathways. Humans may suffer from diarrhea, hemorrhagic colitis ( HC) and hemolytic uremic syndrome ( HUS) and even death when infected with Shiga toxin-producing bac-teria. At present, there is no specific treatment for diseases caused by Stx. In recent years, the application of Stx in cancer therapy and imaging has aroused great interest. This review provided a brief overview of Stx in its nomenclature, typing, structure, genetics, pathogenesis and application perspectives.
ABSTRACT
For the past several decades, the infectious disease profile in China has been shifting with rapid developments in social and economic aspects, environment, quality of food, water, housing, and public health infrastructure. Notably, 5 notifiable infectious diseases have been almost eradicated, and the incidence of 18 additional notifiable infectious diseases has been significantly reduced. Unexpectedly, the incidence of over 10 notifiable infectious diseases, including HIV, brucellosis, syphilis, and dengue fever, has been increasing. Nevertheless, frequent infectious disease outbreaks/events have been reported almost every year, and imported infectious diseases have increased since 2015. New pathogens and over 100 new genotypes or serotypes of known pathogens have been identified. Some infectious diseases seem to be exacerbated by various factors, including rapid urbanization, large numbers of migrant workers, changes in climate, ecology, and policies, such as returning farmland to forests. This review summarizes the current experiences and lessons from China in managing emerging and re-emerging infectious diseases, especially the effects of ecology, climate, and behavior, which should have merits in helping other countries to control and prevent infectious diseases.
Subject(s)
Humans , Behavior , China , Epidemiology , Climate , Communicable Diseases , Classification , Epidemiology , Communicable Diseases, Emerging , Epidemiology , Disease Outbreaks , Ecology , Forecasting , IncidenceABSTRACT
We investigated the carrying situation of Escherichia albertii from healthy people engaged in breeding and slaughtering poultry for a long time.We collected stool samples from people engaged in breeding and slaughtering poultry and other healthy people.After enriched with EC broth,eae-positive enrichment culture was directly streaked on MacConkey,and eaepositive lactose non-fermenting isolate was retained for further investigation.The 16S rDNA sequencing and multilocus sequence typing (MLST) were applied in the identification of E.albertii from suspected strains.Intimin subtypes and cdtB types of E.albertii strains were detected.Pulsed-field gel electrophoresis (PFGE) was used to detected genetic polymorphism of strains from this study and animal source ones.Results showed that two isolates were identified as E.albertii from 189 stools of people exposed to slaughtering chickens and ducks and one from 58 stools in control groups.No isolate was identified as E.albertii from 138 stools samples of people exposed to breeding poultry.Intimin subtypes of three isolates from stool samples were subtyped as sigma,iota 2,nu,and cdtB types were closely related to types Ⅱ/Ⅲ/Ⅴ.PFGE patterns of the three strains was distinguishable (＜80％ similarity),and appeared in different cluster with chickens,ducks and other sources of E.albertii strains.The rate of carrying E.albertii to a certain extent exist in healthy people engaged in slaughtering chickens and ducks,and the relationship between these strains and strains from poultry should be further investigated.
ABSTRACT
Objective To understand the molecular characteristics of human-derived non-O157 Shiga toxin-producing Escherichia coil (STEC) strains circulating in five regions of China.Methods Twenty-seven non-O157 STEC strains isolated in five geographic regions were investigated by serotyping, stx1/stx2 subtyping and PCR screening for adhesion and other virulence genes.A multilocus sequence typing (MLST) scheme provided by E.coil MLST database were performed to amplify and sequence seven housekeeping genes (adk, icd, fumC, rgyrB, purA, mdh and recA) in those strains.Results Twenty-seven non-O157 STEC strains were typed into 16 O∶H serotypes.Among those strains, 11 harbored stx1a, 12 harbored stx1c, two harbored stx2e and the other three strains respectively harbored stx1a+stx2b, stx2d and stx2g.Positive rates of eae, efa1, saa, paa, toxB, astA and ehxA genes were 18.5%, 18.5%, 29.6%, 22.2%, 11.1%, 11.1% and 25.9%, respectively.The 27 strains were typed into 16 different sequence types (STs) based upon MLST.Conclusion Human-derived non-O157 STEC strains circulating in five regions of China are heterogeneous in their serotypes, stx1/stx2 subtypes and virulence gene profiles.
ABSTRACT
Objective To investigate the antibiotic resistance, virulence genes, and sequence types of Enterococcus faecium ( E. faecium) strains isolated from children under 3 years old in Sui county, Henan province. Methods Kirby-Bauer antibiotic testing was performed to analyze the antibiotic sensitivi-ties of E. faecium strains to 15 common antibiotics. PCR analysis was used to detect the virulence genes car-ried by the E. faecium strains. Multilocus sequence typing ( MLST) was performed for the typing of E. faeci-um strains. Results Forty-seven E. faecium strains were isolated from 120 stool samples collected from chil-dren under 3 years old in Sui county, Henan province, of which 95. 7% were antibiotic-resistant strains. Most of the isolated E. faecium strains were resistant to rifampicin, accounting for 91. 5% (43/47) of all isolates, followed by those resistant to erythromycin and tetracycline, which accounted for 68. 1% (32/47). Moreover, high resistance rates to those antibiotics commonly used in clinical treatments of E. faecium infec-tion including β-lactam and aminoglycosides antibiotics were observed. Those strains resistant to more than three kinds of antibiotics belonged to the same clonal complex including 12 strains of clonal complex 17 ( CC17) harboring the virulence gene of hyl. All of the isolated E. faecium strains were susceptible to vanco-mycin, linezolid, chloromycetin and nitrofurantoin. Conclusion The E. faecium strains isolated from chil-dren under 3 years old in Sui county, Henan province were multi-antibiotic resistant. There were drug-resist-ance strains belonging to the CC17 and carrying the virulence gene of hyl.
ABSTRACT
<p><b>OBJECTIVE</b>To understand the distribution of diarrheagenic Escherichia (E.) coli in population in Shanghai and discuss the practice model of cooperation in enteric infectious disease prevention and control between public health institution and hospital.</p><p><b>METHODS</b>Sentinel hospitals were assigned, standard detection and identification of diarrheagenic E. coli were conducted, incidence curve of diarrheagenic E. coli infection was drawn and epidemiologic survey and laboratory detection were conducted for suspect diarrheagenic E. coli infection outbreaks.</p><p><b>RESULTS</b>A total of 7 204 stool specimens were collected from diarrhea patients in 4 hospitals during 2012-2013, in which 712 (9.9% ) were diarrheagenic E. coli positive, including 351 enteropathogenic E. coli (EPEC) strains, 292 enterotoxigenic E. coli (ETEC) strains, 32 enteroinvasive E. coli(EIEC) strains and 6 Shiga toxin-producing E. coli (STEC/EHEC) strains, as well as 31 mixed strains. EPEC infection mainly occurred in children aged 1-5 years; and all of these infections were caused by aEPEC. The incidence peak of ETEC infection was during August, the positive rate was >20%. The ETEC infection mainly occurred in infants aged 1-28 days in 2012 and in people aged 20-60 years in 2013 (P<0.05). ST was the major type (59.6%), followed by LT (27.8%) and ST/LT (12.6%). EIEC infection increased in children obviously in 2013 (P<0.01). No EHEC O157:H7 case was detected, but two EHEC O26:H11 (eae-hlyA-stx1a) cases in children were reported for the first time in Shanghai. The survey result indicated that the multidrug-resistant ETEC (STh-CS21-CFA/I-ClyA-EatA-ST2332-SHNL0005) strain causing outbreak in 15 newborns in Shanghai in 2012 was in the same clone as the strain detected in Zigong in Sichuan province.</p><p><b>CONCLUSION</b>Significant change has occurred in diarrheagenic E. coli distribution in Shanghai in recent years, ETEC has potential risk to cause outbreak of hospital acquired infection in neonates and food borne infection. The active surveillance on ETEC and other enteric pathogens by both public health institutions and hospitals need to be improved.</p>
Subject(s)
Adult , Child, Preschool , Humans , Infant , Infant, Newborn , Middle Aged , Young Adult , China , Epidemiology , Diarrhea , Microbiology , Disease Outbreaks , Enteropathogenic Escherichia coli , Enterotoxigenic Escherichia coli , Escherichia coli Infections , Epidemiology , Incidence , Sentinel SurveillanceABSTRACT
<p><b>OBJECTIVE</b>To investigate the molecular typing feature of enteropathogenic Escherichia coli (EPEC) strains isolated from different reservoirs in eight provinces of China from 2006 to 2014.</p><p><b>METHODS</b>According to the time, place, reservoir, and PFGE pattern of the EPEC strains isolated from stools of humans with diarrhea, animal feces, and foods in eight provinces of China between 2006 and 2014, 149 EPEC strains were selected and characterized by multilocus sequence typing (MLST) using seven housekeeping genes provided by E.coli MLST database. Strain analysis demonstrated 56 different sequence types (STs). SeqMan II, MEGA 5.05, and eBURST V3 were applied to analyze the genetic relationships of domestic and forein existing 392 strains (243 EPEC strains included in the E.coli MLST database and 149 EPEC strains comprised in the present study).</p><p><b>RESULTS</b>Among the 56 different STs, the prevalent ST was ST-40, which included 19 (19/149, 12.8%) isolates. Nineteen new STs were identified. Eleven new alleles were detected in six house-keeping genes (adk, fumC, gyrB, icd, mdh, and purA). Six STs were simultaneously detected among EPEC strains isolated from patients with diarrhea and animals. And these EPEC strains were all aEPEC strains. Two STs were simultaneously identified among EPEC strains isolated from patients with diarrhea and foods. Also, these EPEC strains were all aEPEC strains. 33 out of 173 STs were divided into five major clone complexes by eBURST, STC-29, STC-10, STC-20, STC-28, and STC-517. The remaining EPEC strains included in the other 140 STs were part of the other clone complexes or just were singletons.</p><p><b>CONCLUSION</b>A high degree of phylogenetic heterogeneity was observed among the EPEC strains isolated in eight provinces of China. The EPEC strains with same STs of human isolates isolated from animal feces and foods were all aEPEC strains.</p>
Subject(s)
Animals , Humans , China , Diarrhea , Enteropathogenic Escherichia coli , Escherichia coli , Escherichia coli Proteins , Feces , Multilocus Sequence Typing , PhylogenyABSTRACT
Objective To analyze the subtypes of eae genes in various non-O157 Shiga toxin-pro-ducing Escherichia coli ( STEC) strains isolated in China.Methods The complete nucleotide sequences of 10 eae genes were amplified by PCR and sequenced.The BLASTn software was used to analyze the se-quences for eae gene subtyping.A phylogenetic tree was constructed based on the10 ea e gene sequences to-gether with the gene sequences of 30 different subtypes in GenBank and those of STEC strains of 7 prevalent serotypes (O157 ∶H7, O26 ∶H11, O103 ∶H2, O111 ∶H8, O145 ∶H28, O45 ∶H2 and O121 ∶H19) using MEGA 5.0.Multilocus sequence typing (MLST) was performed on the 10 STEC strains with reference to the Escherichia coli ( E.coli) MLST website ( http://mlst.warwick.ac.uk/mlst/dbs/Ecoli) for the typing of multiple loci.A minimum spanning tree ( MST) was constructed using the BioNumerics software to inves-tigate the phylogenetic relationships between the 10 eae gene-positive STEC strains in this study and hemolyt-ic uremic syndrome-associated enterohemorrhagic E.coli ( HUSEC) strains as well as all human STEC strains of O157, O26, O45, O103, O111, O121 and O145 serotypes submitted to the E.coli MLST website data-base.Results The complete nucleotide sequences of eae genes in 10 non-O157 STEC strains were 2.8 kb in length and belonged to 3 known subtypes.The predominant subtype wasβ1, accounting for 60%of the 10 STEC strains (6/10), followed byθandγ1 subtypes with two strains in each type.The eae gene sequences in certain strains were identical to those of the prevalent serotypes.Seven sequence types ( STs) were identi-fied from the 10 STEC strains carrying eae gene.Conclusion The eae genes harbored by the non-O157 STEC strains isolated from different specimens in China were diverse and had close phylogenetic relationships with the highly pathogenic and prevalent STEC strains.This study implied that the STEC strains harboring eae gene had high pathogenic potential.
ABSTRACT
Objective To investigate the effects of shiga toxin ( Stx ) phage on the expression of type Ⅲsecretion system (T3SS) in E.coli O157 ∶H7.Methods A standard E.coli O157 ∶H7 strain, EDL933 and a natural Stx phage defective mutant of EDL 933 strain, TUV93-0 were used for this study .The expression of T3SS proteins was compared between EDL 933 and TUV93-0 strains.The expression of five operons ( LEE1-LEE5 ) was evaluated by measuring the green fluorescent protein ( GFP ) in five different plasmids with LEE1-LEE5 promoters, respectively.Results The expression of T3SS proteins in TUV93-0 mutant were significantly increased than those in EDL 933 strain.Moreover, the expression of LEE1, LEE2 and LEE5 were also increased in TUV93-0 mutant.Conclusion The deletion of Stx phage might enhance T3SS expression through the regulation of LEE 1.
ABSTRACT
Objective To investigate the tellurite resistance level,the presence of tellurite resistance (ter) gene cluster and their relationships in non-O157 Shiga toxin-producing Escherichia coli(STEC) isolates.Methods Tellurite resistance level was evaluated by plate dilution method and the ter gene cluster was tested by PCR.Results Only 5 of 39 non-O157 STEC isolates tested in this study were identified to have ter gene cluster,which showed relatively high levels of tellurite resistance ranging from 128 μg/ml to 512 μg/ml.In contrast,the other 34 isolates without ter gene cluster were sensitive to potassium tellurite and showed very low levels of tellurite resistance,the minimal inhibitory concentration (MIC) was ＜1 μg/ml for 29 isolates,8 μg/ml for 2 isolates and 2 μg/ml for 3 isolates.Conclusion Most non-O157 STEC isolates were sensitive to potassium tellurite.It could be concluded that much attention should be paid when screening the non-O157 STEC isolates using the selective medium supplemented with potassium tellurite.
ABSTRACT
Objective To investigate the effect of FNR on type Ⅲ secretion system (T3SS) in E.coli O157 ∶ H7.Methods fnr mutant was constructed by λRed recombineering technology promoted by Bet and Exo proteins using PCR products.Results Through bacterial infection assays and immunofluorescence microscopy,it was found that the adhesion ability was decreased insignificantly infnr mutant compared to the wild type ZAP198.However,the secreted proteins were reduced significantly in the mutant from the secretion profile.Conclusion The reason might be that high ClpXP protein caused by the deletion of fnr degraded GrlA resulting in the inhibition of LEE(locus of enterocyte effacement) and T3SS.
ABSTRACT
Eight geographical isolates of Schistosoma japonicum from Taiwan and mainland China and one isolate of Schistosoma mansoni were studied by RAPD analysis using six arbitrary primers and SSR-PCR analysis using a (CA)8RY primer. The genetic distance was determined by the percentage of unshared bands. The RAPD and SSR-PCR results showed that the genetic distance between S. mansoni and S. japonicum was more than 0.900 and 0.850 respectively; the genetic distance between the eight geographical isolates of S. japonicum was 0.000 to 0.232 and 0.066 to 0.368 respectively. These results demonstrated the usefulness of RAPD and SSR-PCR for showing the differences of inter- and intra-species of Schistosoma. The results also suggest that there is genetic diversity among the different geographical strains of S. japonicum in China.