Shiga Toxin�Cproducing Escherichia coli Strains Negative for Locus of Enterocyte Effacement

Most Shiga toxin–producing Escherichia coli (STEC) infections that are associated with severe sequelae such as hemolytic uremic syndrome (HUS) are caused by attaching and effacing pathogens that carry the locus of enterocyte effacement (LEE). However, a proportion of STEC isolates that do not carry LEE have been associated with HUS. To clarify the emergence of LEE-negative STEC, we compared the genetic composition of the virulence plasmids pO113 and pO157 from LEE-negative and LEE-positive STEC, respectively. The complete nucleotide sequence of pO113 showed that several plasmid genes were shared by STEC O157:H7. In addition, allelic profiling of the ehxA gene demonstrated that pO113 belongs to a different evolutionary lineage than pO157 and that the virulence plasmids of LEE-negative STEC strains were highly related. In contrast, multilocus sequence typing of 17 LEE-negative STEC isolates showed several clonal groups, suggesting that pathogenic LEE-negative STEC has emerged several times throughout its evolution.     

Shiga Toxin–Associated Hemolytic Uremic Syndrome in Adults,France, 2009–2017

We conducted a retrospective study on hemolytic uremic syndrome caused by Shiga toxin–producing Escherichia coli (STEC) in 96 adults enrolled in the cohort of the National Reference Center for Thrombotic Microangiopathies network in France during 2009–2017. Most infections were caused by STEC strains not belonging to the O157 or O104 serogroups. Thirty (31.3%) patients had multiple risk factors for thrombotic microangiopathy. In total, 61 (63.5%) patients required dialysis, 50 (52.1%) had a serious neurologic complication, 34 (35.4%) required mechanical ventilation, and 19 (19.8%) died during hospitalization. We used multivariate analysis to determine that the greatest risk factors for death were underlying immunodeficiency (hazard ratio 3.54) and severe neurologic events (hazard ratio 3.40). According to multivariate analysis and propensity score-matching, eculizumab treatment was not associated with survival. We found that underlying conditions, especially immunodeficiency, are strongly associated with decreased survival in adults who have hemolytic uremic syndrome caused by STEC.     

Spatiotemporal Dynamics of Sporadic Shiga Toxin–Producing Escherichia coli Enteritis,Ireland, 2013–2017

The Republic of Ireland regularly reports the highest annual crude incidence rates of Shiga toxin–producing Escherichia coli (STEC) enteritis in the European Union, ≈10 times the average. We investigated spatiotemporal patterns of STEC enteritis in Ireland using multiple statistical tools. Overall, we georeferenced 2,755 cases of infection during January 2013–December 2017; we found >1 case notified in 2,340 (12.6%) of 18,641 Census Small Areas. We encountered the highest case numbers in children 0–5 years of age (n = 1,101, 39.6%) and associated with serogroups O26 (n = 800, 29%) and O157 (n = 638, 23.2%). Overall, we identified 17 space-time clusters, ranging from 2 (2014) to 5 (2017) clusters of sporadic infection per year; we detected recurrent clustering in 3 distinct geographic regions in the west and mid-west, all of which are primarily rural. Our findings can be used to enable targeted epidemiologic intervention and surveillance.     

Geographic Divergence of Bovine and Human Shiga Toxin–Producing Escherichia coli O157:H7 Genotypes,New Zealand

Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a zoonotic pathogen of public health concern worldwide. To compare the local and large-scale geographic distributions of genotypes of STEC O157:H7 isolates obtained from various bovine and human sources during 2008–2011, we used pulsed-field gel electrophoresis and Shiga toxin–encoding bacteriophage insertion (SBI) typing. Using multivariate methods, we compared isolates from the North and South Islands of New Zealand with isolates from Australia and the United States. The STEC O157:H7 population structure differed substantially between the 2 islands and showed evidence of finer scale spatial structuring, which is consistent with highly localized transmission rather than disseminated foodborne outbreaks. The distribution of SBI types differed markedly among isolates from New Zealand, Australia, and the United States. Our findings also provide evidence for the historic introduction into New Zealand of a subset of globally circulating STEC O157:H7 strains that have continued to evolve and be transmitted locally between cattle and humans.     

Shiga Toxin–Producing Escherichia coli O157, England and Wales, 1983–2012

We evaluated clinical Shiga toxin–producing Escherichia coli O157 infections in England and Wales during 1983–2012 to describe changes in microbiological and surveillance methods. A strain replacement event was captured; phage type (PT) 2 decreased to account for just 3% of cases by 2012, whereas PT8 and PT21/28 strains concurrently emerged, constituting almost two thirds of cases by 2012. Despite interventions to control and reduce transmission, incidence remained constant. However, sources of infection changed over time; outbreaks caused by contaminated meat and milk declined, suggesting that interventions aimed at reducing meat cross-contamination were effective. Petting farm and school and nursery outbreaks increased, suggesting the emergence of other modes of transmission and potentially contributing to the sustained incidence over time. Studies assessing interventions and consideration of policies and guidance should be undertaken to reduce Shiga toxin–producing E. coli O157 infections in England and Wales in line with the latest epidemiologic findings.     

Shiga Toxin�Cproducing Escherichia coli, New Mexico, USA, 2004�C2007

Sporadic infection with Shiga toxin–producing Escherichia coli (STEC) in New Mexico increased from 0.9 cases per 100,000 population (95% confidence interval [CI] 0.5–1.36) in 2004 to 1.7 (95% CI 1.14–2.26) in 2007. Non-O157 STEC was more common in nonwhite residents, children <5 years of age, and urban residents.     

2011-2019年33株人源非O157产志贺毒素大肠埃希菌耐药表型及耐药相关基因分析

目的了解人源非O157产志贺毒素大肠埃希菌(STEC)抗生素耐药表型及耐药基因携带状况。方法33株非O157 STEC菌株来自2011-2019年7个省份,包括青海、黑龙江(各1例),广西、山东(各2例),广东(4例),河南(11例),上海(12例),均分离自感染性腹泻患者粪便标本。采用改良微量肉汤法对非O157 STEC进行19种抗生素最小抑菌浓度(MIC)检测;通过全基因组测序进行O∶H血清分型、多位点序列分型(MLST)及耐药相关基因预测。结果33株非O157 STEC分为19种O∶H血清型、17种MLST序列型;10株菌对1种或以上抗生素耐药,5株为多重耐药菌株,对四环素耐药率最高(30.3%,10株),并检出阿奇霉素耐药菌株(12.1%,4株),但所有菌株均对碳青霉烯类药物敏感;共检出22种耐药基因,全部菌株均携带blaEC基因,并检出超广谱β-内酰胺酶(ESBL)基因型blaCTX-M-15(3.0%,1株),首次检出fosA7基因。结论中国7省份33株人源非O157 STEC中存在多重耐药和阿奇霉素耐药菌株,且携带多种耐药基因型,但均对碳青霉烯类药物敏感。     

Emergence and Polyclonal Dissemination of OXA-244–Producing Escherichia coli,France

Since 2016, OXA-244–producing Escherichia coli has been increasingly isolated in France. We sequenced 97 OXA-244–producing E. coli isolates and found a wide diversity of sequence types and a high prevalence of sequence type 38. Long-read sequencing demonstrated the chromosomal location of bla_OXA-244 inside the entire or truncated Tn51098.     

New Delhi Metallo-β-Lactamase–Producing Enterobacterales Bacteria,Switzerland, 2019–2020

Carbapenemase-producing Enterobacterales (CPE) bacteria are a critical global health concern; New Delhi metallo-β-lactamase (NDM) enzymes account for >25% of all CPE found in Switzerland. We characterized NDM-positive CPE submitted to the Swiss National Reference Center for Emerging Antibiotic Resistance during a 2-year period (January 2019–December 2020) phenotypically and by using whole-genome sequencing. Most isolates were either Klebsiella pneumoniae (59/141) or Escherichia coli (52/141), and >50% were obtained from screening swabs. Among the 108 sequenced isolates, NDM-1 was the most prevalent variant, occurring in 56 isolates, mostly K. pneumoniae (34/56); the next most prevalent was NDM-5, which occurred in 49 isolates, mostly E. coli (40/49). Fourteen isolates coproduced a second carbapenemase, predominantly an OXA-48-like enzyme, and almost one third of isolates produced a 16S rRNA methylase conferring panresistance to aminoglycosides. We identified successful plasmids and global lineages as major factors contributing to the increasing prevalence of NDMs in Switzerland.     

Trends in Population Dynamics of Escherichia coli Sequence Type 131, Calgary,Alberta, Canada, 2006–2016

Global expansion of antimicrobial drug–resistant Escherichia coli sequence type (ST) 131 is unrivaled among human bacteria. Understanding trends among ST131 clades will help with designing prevention strategies. We screened E. coli from blood samples (n = 1,784) obtained in Calgary, Alberta, Canada, during 2006, 2012, and 2016 by PCR for ST131 and positive samples (n = 344) underwent whole-genome sequencing. The incidence rate per 100,000 residents increased from 4.91 during 2006 to 12.35 during 2012 and 10.12 during 2016. ST131 belonged to clades A (10%), B (9%), and C (81%). Clades C1-nonM27 and B were common during 2006, and C2 containing bla_CTX-M-15, C1-M27 containing bla_CTX-M-27, and A were responsible for the increase of ST131 during 2012 and 2016. C2 was the most antimicrobial drug–resistant subclade and increased exponentially over time. Eradicating ST131, more specifically the C2 subclade, will lead to considerable public health benefits for persons in Calgary.     

Fosfomycin Resistance in Escherichia coli,Pennsylvania, USA

Fosfomycin resistance in Escherichia coli is rare in the United States. An extended-spectrum β-lactamase–producing E. coli clinical strain identified in Pennsylvania, USA, showed high-level fosfomycin resistance caused by the fosA3 gene. The IncFII plasmid carrying this gene had a structure similar to those found in China, where fosfomycin resistance is commonly described.     

Reduction in Antimicrobial Use and Resistance to Salmonella,Campylobacter, and Escherichia coli in Broiler Chickens,Canada, 2013–2019

Antimicrobial use contributes to the global rise of antimicrobial resistance (AMR). In 2014, the poultry industry in Canada initiated its Antimicrobial Use Reduction Strategy to mitigate AMR in the poultry sector. We monitored trends in antimicrobial use and AMR of foodborne bacteria (Salmonella, Escherichia coli, and Campylobacter) in broiler chickens during 2013 and 2019. We quantified the effect of antimicrobial use and management factors on AMR by using LASSO regression and generalized mixed-effect models. AMR in broiler chickens declined by 6%–38% after the decrease in prophylactic antimicrobial use. However, the withdrawal of individual compounds, such as cephalosporins and fluoroquinolones, prompted an increase in use of and resistance levels for other drug classes, such as aminoglycosides. Canada’s experience with antimicrobial use reduction illustrates the potential for progressive transitions from conventional antimicrobial-dependent broiler production to more sustainable production with respect to antimicrobial use.     

Mixing of Shiga toxin-producing and enteropathogenic Escherichia coli in a wastewater treatment plant receiving city and slaughterhouse wastewater

Wastewater of human and animal may contain Shiga toxin-producing (STEC) and enteropathogenic (EPEC) Escherichia coli. We evaluated the prevalence of such strains in a wastewater treatment plant (WWTP) receiving both city and slaughterhouse wastewater. PCR screenings were performed on 12,248 E. coli isolates. The prevalence of STEC in city wastewater, slaughterhouse wastewater and treated effluent was 0.22%, 0.07% and 0.22%, respectively. The prevalence of EPEC at the same sampling sites was 0.63%, 0.90% and 0.55%. No significant difference was observed between the sampling points. Treatment had no impact on these prevalences. Enterohemorrhagic E. coli (EHEC) O157:H7 and O111:H8 were isolated from the treated effluent rejected into the river. The characteristics of STEC and EPEC differed according to their origin. City wastewater contained STEC with various stx subtypes associated with serious human disease, whereas slaughterhouse wastewater contained exclusively STEC with stx_2e subtype. All the EPEC strains were classified as atypical and were screened for the ε, γ1 and β1 subtypes, known to be associated with the EHEC mainly involved in human infections in France. In city wastewater, eae subtypes remained largely unidentified; whereas eae-β1 was the most frequent subtype in slaughterhouse wastewater. Moreover, the EPEC isolated from slaughterhouse wastewater were positive for other EHEC-associated virulence markers, including top five serotypes, the ehxA gene, putative adherence genes and OI-122 associated genes. The possibility that city wastewater could contain a pool of stx genes associated with human disease and that slaughterhouse wastewater could contain a pool of EPEC sharing similar virulence genes with EHEC, was highlighted. Mixing of such strains in WWTP could lead to the emergence of EHEC by horizontal gene transfer.     

Whole-Genome Sequencing of Shiga Toxin–Producing Escherichia coli OX18 from a Fatal Hemolytic Uremic Syndrome Case

We report a fatal case of hemolytic uremic syndrome with urinary tract infection in Japan caused by Shiga toxin–producing Escherichia coli. We genotypically identified the isolate as OX18:H2. Whole-genome sequencing revealed 3 potentially pathogenic lineages (OX18:H2, H19, and H34) that have been continuously isolated in Japan.     

Global Incidence of Carbapenemase-Producing Escherichia coli ST131

We characterized Escherichia coli ST131 isolates among 116 carbapenemase-producing strains. Of isolates from 16 countries collected during 2008–2013, 35% belonged to ST131 and were associated with bla_KPC, H30 lineage, and virotype C. This study documents worldwide incidents of resistance to “last resort” antimicrobial drugs among a common pathogen in a successful sequence type.     

Limited Dissemination of Extended-Spectrum β-Lactamase– and Plasmid-Encoded AmpC–Producing Escherichia coli from Food and Farm Animals,Sweden

Extended-spectrum β-lactamase (ESBL)– and plasmid-encoded ampC (pAmpC)–producing Enterobacteriaceae might spread from farm animals to humans through food. However, most studies have been limited in number of isolates tested and areas studied. We examined genetic relatedness of 716 isolates from 4,854 samples collected from humans, farm animals, and foods in Sweden to determine whether foods and farm animals might act as reservoirs and dissemination routes for ESBL/pAmpC-producing Escherichia coli. Results showed that clonal spread to humans appears unlikely. However, we found limited dissemination of genes encoding ESBL/pAmpC and plasmids carrying these genes from foods and farm animals to healthy humans and patients. Poultry and chicken meat might be a reservoir and dissemination route to humans. Although we found no evidence of clonal spread of ESBL/pAmpC-producing E. coli from farm animals or foods to humans, ESBL/pAmpC-producing E. coli with identical genes and plasmids were present in farm animals, foods, and humans.     

Whole Genome Sequencing of an Unusual Serotype of Shiga Toxin–producing Escherichia coli

Shiga toxin–producing Escherichia coli serotype O117:K1:H7 is a cause of persistent diarrhea in travelers to tropical locations. Whole genome sequencing identified genetic mechanisms involved in the pathoadaptive phenotype. Sequencing also identified toxin and putative adherence genes flanked by sequences indicating horizontal gene transfer from Shigella dysenteriae and Salmonella spp., respectively.     

Prevalence of plasmid-mediated AmpC β-lactamases among uropathogenic Escherichia coli isolates in southwestern Iran

ObjectivesThis study was undertaken to evaluate AmpC β-lactamase-producing Escherichia coli urine isolates and to characterize the frequency of plasmid-mediated AmpC (pAmpC)-encoding genes.MethodsAntimicrobial susceptibility tests were performed using the disk diffusion technique. AmpC β-lactamase production was assessed with a phenotypic inhibitor-based method. The presence of 6 pAmpC-encoding cluster genes was detected by multiplex polymerase chain reaction (PCR).ResultsThe proportion of antibiotic resistance of E. coli isolates ranged from 7.4% to 90.5%, and more than half (51.6%) of the total isolates were multidrug-resistant (MDR). Among the 95 E. coli isolates, 60 (63.2%) were found to be cefoxitin-resistant, but only 14 (14.7%) isolates were confirmed as AmpC β-lactamase-producers. In the PCR assay, pAmpC-encoding genes were found in 15 (15.8%) isolates, and bla_DHA was the most prevalent type. However, bla_FOX, bla_MOX, and bla_ACC genes were not detected in the isolates.ConclusionOur findings contributed valuable information concerning antibiotic resistance, confirmatory phenotypic testing for AmpC production, and pAmpC β-lactamase gene content in E. coli isolates in southwestern Iran. The level of MDR recorded in AmpC-producing strains of this study was worrying; therefore, implementing strong infection control approaches to reduce the MDR burden is recommended.     

Natural and synthetic plant compounds as anti-biofilm agents against Escherichia coli O157:H7 biofilm

Escherichia coli is a common gram-negative bacterium found in the gut and intestinal tract of warm-blooded animals including humans. An evolved seropathotype E. coli O157:H7 (STEC) came into existence in 1982, since then it has been evolved as a stronger and more robust drug-resistant pathotype of E. coli. This drug resistance is due to horizontal gene transfer, natural gene evolution for survival, and most of the cases due to the ability of STEC to switch to the biofilm growth mode from planktonic lifestyle. During the growth in biofilm mode, Escherichia coli O157:H7 opts more robust ability to grow in adverse environments i.e., in presence of antibiotics and other antimicrobial chemicals. Due to the biofilm matrix, the microbial community acquires drug resistance. This makes the treatment of diseases caused by E. coli O157:H7 a complex challenge. To address the illnesses caused by this biofilm-forming pathogen, there are several possible strategies such as antibiotic therapies, synthetic antimicrobial chemicals, adjunct therapy of synergistic effect of multiple drugs, and more importantly plant originated compounds as a new anti-biofilm candidate. The present review summarizes various phytochemicals and their derivatives reported in the last decade mostly to eliminate the biofilm of STEC. The review will progressively reveal the antibiofilm mechanism of the phytochemicals against STEC and to be a potential candidate for the development of the future antibacterial drugs to STEC induced infections.