Is Shiga Toxin-Negative Escherichia coli O157:H7 Enteropathogenic or Enterohemorrhagic Escherichia coli? Comprehensive Molecular Analysis Using Whole-Genome Sequencing

The ability ofEscherichia coliO157:H7 to induce cellular damage leading to disease in humans is related to numerous virulence factors, most notably thestxgene, encoding Shiga toxin (Stx) and carried by a bacteriophage. Loss of the Stx-encoding bacteriophage may occur during infection or culturing of the strain. Here, we collectedstx-positive andstx-negative variants ofE. coliO157:H7/NM (nonmotile) isolates from patients with gastrointestinal complaints. Isolates were characterized by whole-genome sequencing (WGS), and their virulence properties and phylogenetic relationship were determined. Because of the presence of theeaegene but lack of thebfpAgene, thestx-negative isolates were considered atypical enteropathogenicE. coli(aEPEC). However, they had phenotypic characteristics similar to those of the Shiga toxin-producingE. coli(STEC) isolates and belonged to the same sequence type, ST11. Furthermore, EPEC and STEC isolates shared similar virulence genes, the locus of enterocyte effacement region, and plasmids. Core genome phylogenetic analysis using a gene-by-gene typing approach showed that the sorbitol-fermenting (SF)stx-negative isolates clustered together with an SF STEC isolate and that one non-sorbitol-fermenting (NSF)stx-negative isolate clustered together with NSF STEC isolates. Therefore, thesestx-negative isolates were thought either to have lost the Stx phage or to be a progenitor of STEC O157:H7/NM. As detection of STEC infections is often based solely on the identification of the presence ofstxgenes, these may be misdiagnosed in routine laboratories. Therefore, an improved diagnostic approach is required to manage identification, strategies for treatment, and prevention of transmission of these potentially pathogenic strains.

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Genomic surveillance of Escherichia coli and Klebsiella spp. in hospital sink drains and patients

Microbial Genomics ◽

10.1099/mgen.0.000391 ◽

2020 ◽

Vol 6 (7) ◽

Author(s):

Bede Constantinides ◽

Kevin K. Chau ◽

T. Phuong Quan ◽

Gillian Rodger ◽

Monique I. Andersson ◽

...

Keyword(s):

Escherichia Coli ◽

Antimicrobial Resistance ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Type Species ◽

Whole Genome ◽

Content Type ◽

E Coli ◽

Link Type ◽

Antimicrobial Resistance Genes

Escherichia coli and Klebsiella spp. are important human pathogens that cause a wide spectrum of clinical disease. In healthcare settings, sinks and other wastewater sites have been shown to be reservoirs of antimicrobial-resistant E. coli and Klebsiella spp., particularly in the context of outbreaks of resistant strains amongst patients. Without focusing exclusively on resistance markers or a clinical outbreak, we demonstrate that many hospital sink drains are abundantly and persistently colonized with diverse populations of E. coli , Klebsiella pneumoniae and Klebsiella oxytoca , including both antimicrobial-resistant and susceptible strains. Using whole-genome sequencing of 439 isolates, we show that environmental bacterial populations are largely structured by ward and sink, with only a handful of lineages, such as E. coli ST635, being widely distributed, suggesting different prevailing ecologies, which may vary as a result of different inputs and selection pressures. Whole-genome sequencing of 46 contemporaneous patient isolates identified one (2 %; 95 % CI 0.05–11 %) E. coli urine infection-associated isolate with high similarity to a prior sink isolate, suggesting that sinks may contribute to up to 10 % of infections caused by these organisms in patients on the ward over the same timeframe. Using metagenomics from 20 sink-timepoints, we show that sinks also harbour many clinically relevant antimicrobial resistance genes including bla CTX-M, bla SHV and mcr, and may act as niches for the exchange and amplification of these genes. Our study reinforces the potential role of sinks in contributing to Enterobacterales infection and antimicrobial resistance in hospital patients, something that could be amenable to intervention. This article contains data hosted by Microreact.

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Frequency and Mechanisms of Spontaneous Fosfomycin Nonsusceptibility Observed upon Disk Diffusion Testing of Escherichia coli

Journal of Clinical Microbiology ◽

10.1128/jcm.01368-17 ◽

2017 ◽

Vol 56 (1) ◽

Cited By ~ 16

Author(s):

Aaron E. Lucas ◽

Ryota Ito ◽

Mustapha M. Mustapha ◽

Christi L. McElheny ◽

Roberta T. Mettus ◽

...

Keyword(s):

Escherichia Coli ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Multidrug Resistant ◽

Clinical Isolates ◽

Whole Genome ◽

Zone Of Inhibition ◽

Content Type ◽

E Coli ◽

Disk Diffusion Testing

ABSTRACTFosfomycin maintains activity against mostEscherichia coliclinical isolates, but the growth ofE. colicolonies within the zone of inhibition around the fosfomycin disk is occasionally observed upon susceptibility testing. We aimed to estimate the frequency of such nonsusceptible inner colony mutants and identify the underlying resistance mechanisms. Disk diffusion testing of fosfomycin was performed on 649 multidrug-resistantE. coliclinical isolates collected between 2011 and 2015. For those producing inner colonies inside the susceptible range, the parental strains and their representative inner colony mutants were subjected to MIC testing, whole-genome sequencing, reverse transcription-quantitative PCR (qRT-PCR), and carbohydrate utilization studies. Of the 649E. coliclinical isolates, 5 (0.8%) consistently produced nonsusceptible inner colonies. Whole-genome sequencing revealed the deletion ofuhpTencoding hexose-6-phosphate antiporter in 4 of theE. coliinner colony mutants, while the remaining mutant contained a nonsense mutation inuhpA. The expression ofuhpTwas absent in the mutant strains withuhpTdeletion and was not inducible in the strain with theuhpAmutation, unlike in its parental strain. All 5 inner colony mutants had reduced growth on minimal medium supplemented with glucose-6-phosphate. In conclusion, fosfomycin-nonsusceptible inner colony mutants can occur due to the loss of function or induction of UhpT but are rare among multidrug-resistantE. coliclinical strains. Considering that these mutants carry high biological costs, we suggest that fosfomycin susceptibility of strains that generate inner colony mutants can be interpreted on the basis of the zone of inhibition without accounting for the inner colonies.

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Whole-Genome Sequencing Analysis of a stx-Negative Escherichia coli O63:H6 Isolate Associated with Hemolytic Uremic Syndrome

Diagnostics ◽

10.3390/diagnostics11101823 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1823

Author(s):

Tae Yeul Kim ◽

Tae-Min La ◽

Taesoo Kim ◽

Sun Ae Yun ◽

Sang-Won Lee ◽

...

Keyword(s):

Escherichia Coli ◽

Hemolytic Uremic Syndrome ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Virulence Gene ◽

Enterohemorrhagic Escherichia Coli ◽

Whole Genome ◽

Sequencing Analysis ◽

E Coli ◽

Uremic Syndrome

Shiga toxin-encoding genes (stx) of enterohemorrhagic Escherichia coli (EHEC) can be lost during infection or in vitro cultivation, and in clinical practice, it is difficult to distinguish EHEC that have lost stx (EHEC-LST) from enteropathogenic E. coli (EPEC), as both are stx-negative and eae-positive. In this study, we performed whole-genome sequencing (WGS) of a stx-negative, eae-positive E. coli O63:H6 isolate from a child with hemolytic uremic syndrome and compared its genome with those of nine E. coli O63:H6 strains in public databases. Virulence gene profiles were analyzed and core-genome multilocus sequence typing (cgMLST) was conducted. The virulence gene profile of our isolate was consistent with EHEC, except for the absence of stx, and the isolate clustered with seven EHEC strains but was distant from two EPEC strains in cgMLST. In genome alignment, our isolate exhibited a high nucleotide identity with EHEC strain 377323_2f but displayed a gap corresponding to the stx-harboring prophage sequence. Overall, our isolate was genetically closely related to EHEC strains, consistent with this being an EHEC-LST strain. As EHEC-LST may be misdiagnosed as EPEC in routine laboratories, comparative genomic analysis using WGS can be useful to determine whether stx-negative and eae-positive isolates are EHEC-LST or EPEC.

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MCR-1 and OXA-48 In Vivo Acquisition in KPC-Producing Escherichia coli after Colistin Treatment

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02540-16 ◽

2017 ◽

Vol 61 (8) ◽

Cited By ~ 32

Author(s):

Racha Beyrouthy ◽

Frederic Robin ◽

Aude Lessene ◽

Igor Lacombat ◽

Laurent Dortet ◽

...

Keyword(s):

Escherichia Coli ◽

Klebsiella Pneumoniae ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Whole Genome ◽

Content Type ◽

First Report ◽

E Coli ◽

Carbapenem Resistant

ABSTRACT The spread of mcr-1-encoding plasmids into carbapenem-resistant Enterobacteriaceae raises concerns about the emergence of untreatable bacteria. We report the acquisition of mcr-1 in a carbapenem-resistant Escherichia coli strain after a 3-week course of colistin in a patient repatriated to France from Portugal. Whole-genome sequencing revealed that the Klebsiella pneumoniae carbapenemase-producing E. coli strain acquired two plasmids, an IncL OXA-48-encoding plasmid and an IncX4 mcr-1-encoding plasmid. This is the first report of mcr-1 in carbapenemase-encoding bacteria in France.

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Phenotypic H-Antigen Typing by Mass Spectrometry Combined with Genetic Typing of H Antigens, O Antigens, and Toxins by Whole-Genome Sequencing Enhances Identification of Escherichia coli Isolates

Journal of Clinical Microbiology ◽

10.1128/jcm.00422-16 ◽

2016 ◽

Vol 54 (8) ◽

pp. 2162-2168 ◽

Cited By ~ 4

Author(s):

Keding Cheng ◽

Huixia Chui ◽

Larissa Domish ◽

Angela Sloan ◽

Drexler Hernandez ◽

...

Keyword(s):

Mass Spectrometry ◽

Escherichia Coli ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Shiga Toxin ◽

Gene Pair ◽

Whole Genome ◽

Genetic Typing ◽

Content Type ◽

O Antigens

Mass spectrometry-based phenotypic H-antigen typing (MS-H) combined with whole-genome-sequencing-based genetic identification of H antigens, O antigens, and toxins (WGS-HOT) was used to type 60 clinicalEscherichia coliisolates, 43 of which were previously identified as nonmotile, H type undetermined, or O rough by serotyping or having shown discordant MS-H and serotyping results. Whole-genome sequencing confirmed that MS-H was able to provide more accurate data regarding H antigen expression than serotyping. Further, enhanced and more confident O antigen identification resulted from gene cluster based typing in combination with conventional typing based on the gene pair comprisingwzxandwzyand that comprisingwzmandwzt. The O antigen was identified in 94.6% of the isolates when the two genetic O typing approaches (gene pair and gene cluster) were used in conjunction, in comparison to 78.6% when the gene pair database was used alone. In addition, 98.2% of the isolates showed the existence of genes for various toxins and/or virulence factors, among which verotoxins (Shiga toxin 1 and/or Shiga toxin 2) were 100% concordant with conventional PCR based testing results. With more applications of mass spectrometry and whole-genome sequencing in clinical microbiology laboratories, this combined phenotypic and genetic typing platform (MS-H plus WGS-HOT) should be ideal for pathogenicE. colityping.

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Validation of Whole-Genome Sequencing for Identification and Characterization of Shiga Toxin-ProducingEscherichia coliTo Produce Standardized Data To Enable Data Sharing

Journal of Clinical Microbiology ◽

10.1128/jcm.01388-17 ◽

2017 ◽

Vol 56 (3) ◽

Cited By ~ 5

Author(s):

Anne Holmes ◽

Timothy J. Dallman ◽

Sharif Shabaan ◽

Mary Hanson ◽

Lesley Allison

Keyword(s):

Public Health ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Shiga Toxin ◽

Reference Laboratory ◽

Whole Genome ◽

Public Health Action ◽

Data Set ◽

Content Type ◽

E Coli

ABSTRACTWhole-genome sequencing (WGS) is rapidly becoming the method of choice for outbreak investigations and public health surveillance of microbial pathogens. The combination of improved cluster resolution and prediction of resistance and virulence phenotypes provided by a single tool is extremely advantageous. However, the data produced are complex, and standard bioinformatics pipelines are required to translate the output into easily interpreted epidemiologically relevant information for public health action. The main aim of this study was to validate the implementation of WGS at the ScottishEscherichia coliO157/STEC Reference Laboratory (SERL) using the Public Health England (PHE) bioinformatics pipeline to produce standardized data to enable interlaboratory comparison of results generated at two national reference laboratories. In addition, we evaluated the BioNumerics whole-genome multilocus sequence typing (wgMLST) andE. coligenotyping plug-in tools using the same data set. A panel of 150 well-characterized isolates of Shiga toxin-producingE. coli(STEC) that had been sequenced and analyzed at PHE using the PHE pipeline and database (SnapperDB) was assembled to provide identification and typing data, including serotype (O:H type), sequence type (ST), virulence genes (eaeand Shiga toxin [stx] subtype), and a single-nucleotide polymorphism (SNP) address. To validate the implementation of sequencing at the SERL, DNA was reextracted from the isolates and sequenced and analyzed using the PHE pipeline, which had been installed at the SERL; the output was then compared with the PHE data. The results showed a very high correlation between the data, ranging from 93% to 100%, suggesting that the standardization of WGS between our reference laboratories is possible. We also found excellent correlation between the results obtained using the PHE pipeline and BioNumerics, except for the detection ofstx2aandstx2cwhen these subtypes are both carried by strains.

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Complete Genome Sequence of a Lytic T7-Like Phage, Escherichia Phage vB_EcoP-Ro45lw, Isolated from Nonfecal Compost Samples

Microbiology Resource Announcements ◽

10.1128/mra.00036-19 ◽

2019 ◽

Vol 8 (9) ◽

Cited By ~ 1

Author(s):

Yen-Te Liao ◽

Fang Liu ◽

Vivian C. H. Wu

Keyword(s):

Escherichia Coli ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Genome Sequence ◽

Shiga Toxin ◽

Complete Genome Sequence ◽

Complete Genome ◽

Lytic Phage ◽

Whole Genome ◽

Content Type

Although isolation of the bacteriophages (phages) specific to Shiga toxin-producing Escherichia coli (STEC) is increasing, the number of those specific to STEC non-O157 strains, instead of STEC O157, with whole-genome sequencing characterization is relatively low. Here, we announce the complete genome sequence of a T7-like lytic phage against STEC O45.

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Whole-Genome Sequencing of Multidrug-Resistant Escherichia coli Strains Harboring the mcr-1 Gene, Isolated from Seawater of the Algiers Coast in Algeria

Microbiology Resource Announcements ◽

10.1128/mra.00638-19 ◽

2019 ◽

Vol 8 (34) ◽

Cited By ~ 2

Author(s):

M. Berrazeg ◽

A. Deriet ◽

S. C. J. De Keersmaecker ◽

B. Verhaegen ◽

K. Vanneste ◽

...

Keyword(s):

Escherichia Coli ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Treatment Efficacy ◽

Multidrug Resistant ◽

Whole Genome ◽

Colistin Resistance ◽

Content Type ◽

E Coli

Colistin resistance has emerged worldwide and is threatening the treatment efficacy of multiresistant Escherichia coli strains in humans and animals. Here, we communicate the whole-genome sequencing (WGS) of two colistin-resistant E. coli strains, M49 and M78, with genomes sizes of 4,947,168 and 5,178,716 bp, respectively, isolated from seawaters of the Algiers coast.

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Molecular Epidemiology of Shiga Toxin-ProducingEscherichia coli(STEC) on New Zealand Dairy Farms: Application of a Culture-Independent Assay and Whole-Genome Sequencing

Applied and Environmental Microbiology ◽

10.1128/aem.00481-18 ◽

2018 ◽

Vol 84 (14) ◽

Cited By ~ 13

Author(s):

A. Springer Browne ◽

Anne C. Midwinter ◽

Helen Withers ◽

Adrian L. Cookson ◽

Patrick J. Biggs ◽

...

Keyword(s):

Risk Factors ◽

New Zealand ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Shiga Toxin ◽

Dairy Farms ◽

Whole Genome ◽

Content Type ◽

E Coli ◽

Culture Independent

ABSTRACTNew Zealand has a relatively high incidence of human cases of Shiga toxin-producingEscherichia coli(STEC), with 8.9 STEC cases per 100,000 people reported in 2016. Previous research showed living near cattle and contact with cattle feces as significant risk factors for STEC infections in humans in New Zealand, but infection was not linked to food-associated factors. During the 2014 spring calving season, a random, stratified, cross-sectional study of dairy farms (n= 102) in six regions across New Zealand assessed the prevalence of the “Top 7” STEC bacteria (serogroups O157, O26, O45, O103, O111, O121, and O145) in young calves (n= 1,508), using a culture-independent diagnostic test (PCR/MALDI-TOF). Twenty percent (306/1,508) of calves on 75% (76/102) of dairy farms were positive for at least one of the “Top 7” STEC bacteria. STEC carriage by calves was associated with environmental factors, increased calf age, region, and increased number of calves in a shared calf pen. The intraclass correlation coefficient (ρ) indicated strong clustering of “Top 7” STEC-positive calves for O157, O26, and O45 serogroups within the same pens and farms, indicating that if one calf was positive, others in the same environment were likely to be positive as well. This finding was further evaluated with whole-genome sequencing, which indicated that a singleE. coliO26 clonal strain could be found in calves in the same pen or farm, but different strains existed on different farms. This study provides evidence that would be useful for designing on-farm interventions to reduce direct and indirect human exposure to STEC bacteria.IMPORTANCECattle are asymptomatic carriers of Shiga toxin-producingE. coli(STEC) bacteria that can cause bloody diarrhea and kidney failure in humans if ingested. New Zealand has relatively high numbers of STEC cases, and contact with cattle feces and living near cattle are risk factors for human infection. This study assessed the national prevalence of STEC in young dairy cattle by randomly selecting 102 farms throughout New Zealand. The study used a molecular laboratory method that has relatively high sensitivity and specificity compared to traditional methods. “Top 7” STEC was found in 20% of calves on 75% of the farms studied, indicating widespread prevalence across the country. By examining the risk factors associated with calf carriage, potential interventions that could decrease the prevalence of “Top 7” STEC bacteria at the farm level were identified, which could benefit both public health and food safety.

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Utility of Whole-Genome Sequencing of Escherichia coli O157 for Outbreak Detection and Epidemiological Surveillance

Journal of Clinical Microbiology ◽

10.1128/jcm.01066-15 ◽

2015 ◽

Vol 53 (11) ◽

pp. 3565-3573 ◽

Cited By ~ 48

Author(s):

Anne Holmes ◽

Lesley Allison ◽

Melissa Ward ◽

Timothy J. Dallman ◽

Richard Clark ◽

...

Keyword(s):

Escherichia Coli ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Outbreak Detection ◽

Epidemiological Surveillance ◽

Personal Genome ◽

Whole Genome ◽

Content Type ◽

E Coli ◽

Antimicrobial Resistance Genes

Detailed laboratory characterization ofEscherichia coliO157 is essential to inform epidemiological investigations. This study assessed the utility of whole-genome sequencing (WGS) for outbreak detection and epidemiological surveillance ofE. coliO157, and the data were used to identify discernible associations between genotypes and clinical outcomes. One hundred fiveE. coliO157 strains isolated over a 5-year period from human fecal samples in Lothian, Scotland, were sequenced with the Ion Torrent Personal Genome Machine. A total of 8,721 variable sites in the core genome were identified among the 105 isolates; 47% of the single nucleotide polymorphisms (SNPs) were attributable to six “atypical”E. coliO157 strains and included recombinant regions. Phylogenetic analyses showed that WGS correlated well with the epidemiological data. Epidemiological links existed between cases whose isolates differed by three or fewer SNPs. WGS also correlated well with multilocus variable-number tandem repeat analysis (MLVA) typing data, with only three discordant results observed, all among isolates from cases not known to be epidemiologically related. WGS produced a better-supported, higher-resolution phylogeny than MLVA, confirming that the method is more suitable for epidemiological surveillance ofE. coliO157. A combination ofinsilicoanalyses (VirulenceFinder, ResFinder, and local BLAST searches) were used to determinestxsubtypes, multilocus sequence types (15 loci), and the presence of virulence and acquired antimicrobial resistance genes. There was a high level of correlation between the WGS data and our routine typing methods, although some discordant results were observed, mostly related to the limitation of short sequence read assembly. The data were used to identify sublineages and clades ofE. coliO157, and when they were correlated with the clinical outcome data, they showed that one clade, Ic3, was significantly associated with severe disease. Together, the results show that WGS data can provide higher resolution of the relationships betweenE. coliO157 isolates than that provided by MLVA. The method has the potential to streamline the laboratory workflow and provide detailed information for the clinical management of patients and public health interventions.

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