Epidemic profile of Shiga-toxin-producing Escherichia coli O104:H4 outbreak in Germany

Shiga Toxin-Associated Hemolytic Uremic Syndrome: A Narrative Review

The severity of human infection by one of the many Shiga toxin-producing Escherichia coli (STEC) is determined by a number of factors: the bacterial genome, the capacity of human societies to prevent foodborne epidemics, the medical condition of infected patients (in particular their hydration status, often compromised by severe diarrhea), and by our capacity to devise new therapeutic approaches, most specifically to combat the bacterial virulence factors, as opposed to our current strategies that essentially aim to palliate organ deficiencies. The last major outbreak in 2011 in Germany, which killed more than 50 people in Europe, was evidence that an effective treatment was still lacking. Herein, we review the current knowledge of STEC virulence, how societies organize the prevention of human disease, and how physicians treat (and, hopefully, will treat) its potentially fatal complications. In particular, we focus on STEC-induced hemolytic and uremic syndrome (HUS), where the intrusion of toxins inside endothelial cells results in massive cell death, activation of the coagulation within capillaries, and eventually organ failure.

Hemolytic uremic syndrome caused by Shiga toxin-producing Escherichia coli in children: incidence, risk factors, and clinical outcome

BACKGROUND

Hemolytic uremic syndrome (HUS) is a multisystemic disease. In a nationwide study, we characterized the incidence, clinical course, and prognosis of HUS caused by Shiga toxin (Stx)-producing Escherichia coli (STEC) strains with emphasis on risk factors, disease severity, and long-term outcome.

METHODS

The data on pediatric HUS patients from 2000 to 2016 were collected from the medical records. STEC isolates from fecal cultures of HUS and non-HUS patients were collected from the same time period and characterized by whole genome sequencing analysis.

RESULTS

Fifty-eight out of 262 culture-positive cases developed verified (n = 58, 22%) STEC-HUS. Another 29 cases had probable STEC-HUS, the annual incidence of STEC-HUS being 0.5 per 100,000 children. Eleven different serogroups were detected, O157 being the most common (n = 37, 66%). Age under 3 years (OR 2.4), stx2 (OR 9.7), and stx2a (OR 16.6) were found to be risk factors for HUS. Fifty-five patients (63%) needed dialysis. Twenty-nine patients (33%) developed major neurological symptoms. Complete renal recovery was observed in 57 patients after a median 4.0 years of follow-up. Age under 3 years, leukocyte count over 20 × 10⁹/L, and need for dialysis were predictive factors for poor renal outcome.

CONCLUSIONS

Age under 3 years, stx2, and stx2a were risk factors for HUS in STEC-positive children. However, serogroup or stx types did not predict the renal outcome or major CNS symptoms.

Origin and Evolution of Hybrid Shiga Toxin-Producing and Uropathogenic Escherichia coli Strains of Sequence Type 141

Hybrid Shiga toxin-producing Escherichia coli (STEC) and uropathogenic E. coli (UPEC) strains of multilocus sequence type 141 (ST141) cause both urinary tract infections and diarrhea in humans and are phylogenetically positioned between STEC and UPEC strains. We used comparative genomic analysis of 85 temporally and spatially diverse ST141 E. coli strains, including 14 STEC/UPEC hybrids, collected in Germany (n = 13) and the United States (n = 1) to reconstruct their molecular evolution. Whole-genome sequencing data showed that 89% of the ST141 E. coli strains either were STEC/UPEC hybrids or contained a mixture of virulence genes from other pathotypes. Core genome analysis and ancestral reconstruction revealed that the ST141 E. coli strains clustered into two lineages that evolved from a common ancestor in the mid-19th century. The STEC/UPEC hybrid emerged ∼100 years ago by acquiring an stx prophage, which integrated into previously unknown insertion site between rcsB and rcsD, followed by the insertion of a pathogenicity island (PAI) similar to PAI II of UPEC strain 536 (PAI II536-like). The two variants of PAI II536-like were associated with tRNA genes leuX and pheU, respectively. Finally, microevolution within PAI II536-like and acquisition of the enterohemorrhagic E. coli plasmid were observed. Our data suggest that intestinal pathogenic E. coli (IPEC)/extraintestinal pathogenic E. coli (ExPEC) hybrids are widespread and that selection pressure within the ST141 E. coli population led to the emergence of the STEC/UPEC hybrid as a clinically important subgroup. We hypothesize that ST141 E. coli strains serve as a melting pot for pathogroup conversion between IPEC and ExPEC, contrasting the classical theory of pathogen emergence from nonpathogens and corroborating our recent phenomenon of heteropathogenicity among pathogenic E. coli strains.

O-serogroups, virulence genes, antimicrobial susceptibility, and MLST genotypes of Shiga toxin-producing Escherichia coli from swine and cattle in Central China

Background

Shiga toxin-producing Escherichia coli (STEC) is a leading cause of worldwide food-borne and waterborne infections. Despite an increase in the number of STEC outbreaks, there is a lack of data on prevalence of STEC at the farm level, distribution of serogroups, and virulence factors.

Results

In the present study, a total of 91 (6.16%) STEC strains were isolated from 1477 samples including pig intestines, pig feces, cattle feces, milk, and water from dairy farms. The isolation rates of STEC strains from pig intestines, pig feces, and cattle feces were 7.41% (32/432), 4.38% (21/480), and 9.57% (38/397), respectively. No STEC was isolated from the fresh milk and water samples. By O-serotyping methods, a total of 30 types of O-antigens were determined, and the main types were O100, O97, O91, O149, O26, O92, O102, O157, and O34. Detection of selected virulence genes (stx₁, stx₂, eae, ehxA, saa) revealed that over 94.51% (86/91) of the isolates carried more than two types of virulence associated genes, and approximately 71.43% (65/91) of the isolates carried both stx₁ and stx₂, simultaneously. Antimicrobial susceptibility tests showed that most of the STEC isolates were susceptible to ofloxacin and norfloxacin, but showed resistance to tetracycline, kanamycin, trimethoprim-sulfamethoxazole, streptomycin, amoxicillin, and ampicillin. MLST determined 13 categories of sequence types (STs), and ST297 (31.87%; 29/91) was the most dominant clone. This clone displayed a close relationship to virulent strains STEC ST678 (O104: H4). The prevalence of ST297 clones should receive more attentions.

Conclusions

Our preliminary data revealed that a heterogeneous group of STEC is present, but the non-O157 serogroups and some ST clones such as ST297 should receive more attentions.

The Role of Pathogenic E. coli in Fresh Vegetables: Behavior, Contamination Factors, and Preventive Measures

Many raw vegetables, such as tomato, chili, onion, lettuce, arugula, spinach, and cilantro, are incorporated into fresh dishes including ready-to-eat salads and sauces. The consumption of these foods confers a high nutritional value to the human diet. However, the number of foodborne outbreaks associated with fresh produce has been increasing, with Escherichia coli being the most common pathogen associated with them. In humans, pathogenic E. coli strains cause diarrhea, hemorrhagic colitis, hemolytic uremic syndrome, and other indications. Vegetables can be contaminated with E. coli at any point from pre- to postharvest. This bacterium is able to survive in many environmental conditions due to a variety of mechanisms, such as adhesion to surfaces and internalization in fresh products, thereby limiting the usefulness of conventional processing and chemical sanitizing methods used by the food industry. The aim of this review is to provide a general description of the behavior and importance of pathogenic E. coli in ready-to-eat vegetable dishes. This information can contribute to the development of effective control measures for enhancing food safety.

Top-Down Proteomic Identification of Shiga Toxin 1 and 2 from Pathogenic Escherichia coli Using MALDI-TOF-TOF Tandem Mass Spectrometry

Shiga-toxin-producing Escherichia coli (STEC) are a burden on agriculture and a threat to public health. Rapid methods are needed to identify STEC strains and characterize the Shiga toxin (Stx) they produce. We analyzed three STEC strains for Stx expression, using antibiotic induction, matrix-assisted laser desorption/ionization time-of-flight-time-of-flight (MALDI-TOF-TOF) mass spectrometry, and top-down proteomic analysis. E. coli O157:H- strain 493/89 is a clinical isolate linked to an outbreak of hemolytic uremic syndrome (HUS) in Germany in the late 1980s. E. coli O145:H28 strains RM12367-C1 and RM14496-C1 were isolated from an agricultural region in California. The stx operon of the two environmental strains were determined by whole genome sequencing (WGS). STEC strain 493/89 expressed Shiga toxin 2a (Stx2a) as identified by tandem mass spectrometry (MS/MS) of its B-subunit that allowed identification of the type and subtype of the toxin. RM12367-C1 also expressed Stx2a as identified by its B-subunit. RM14496-C1 expressed Shiga toxin 1a (Stx1a) as identified from its B-subunit. The B-subunits of Stx1 and Stx2 both have an intramolecular disulfide bond. MS/MS was obtained on both the disulfide-bond-intact and disulfide-bond-reduced B-subunit, with the latter being used for top-down proteomic identification. Top-down proteomic analysis was consistent with WGS.

Detection of Escherichia coli O157:H7 and Shiga toxin 2a gene in pork, pig feces, and clean water at Jagalan slaughterhouse in Surakarta, Central Java Province, Indonesia

Background and Aim

The feasibility assessment of food products on the market becomes one of the milestones of food safety. The quality of food safety of animal origin especially pork need to get attention and more real action from the parties related and concerned. Since pork is also a source of transmission for the contagion of foodborne disease so that the study of the existence of several agents in the pork and its products become the benchmark of safety level. This study aimed to isolate, identify, and detect the Shiga toxin 2a (stx2a) gene from Escherichia coli O157:H7 in pork, pig feces, and clean water in the Jagalan slaughterhouse.

Materials and Methods

A total of 70 samples consisting of 32 pork samples, 32 pig fecal samples, and 6 clean water samples were used to isolate and identify E. coli O157:H7 and the stx2a gene. Isolation and identification of E. coli O157:H7 were performed using culture on eosin methylene blue agar and Sorbitol-MacConkey agar media and confirmed molecularly with polymerase chain reaction to amplify the target genes rfbE (317 bp) and fliC (381 bp). The isolates, which were identified as E. coli O157:H7, were investigated for the stx2a gene (553 bp).

Results

The results of this study show that of the total collected samples, E. coli O157:H7 was 28.6% in Jagalan slaughterhouse and consisted of 25% of pork samples, 31.25% of pig fecal samples, and 33.3% of clean water samples. The isolates that were identified to be E. coli O157:H7 mostly contained the stx2a gene, which was equal to 75%, and consisted of seven isolates from pork samples, seven isolates from fecal samples, and one isolate from clean water samples.

Conclusion

E. coli O157:H7 was found in 28.6% of pork, pig feces, and clean water in Jagalan slaughterhouse and 75% of identified E. coli O157:H7 contained the stx2a gene.

An outbreak and case-control study of Salmonella Havana linked to alfalfa sprouts in South Australia, 2018

An epidemiological investigation and a retrospective case-control study were conducted into an outbreak of Salmonella Havana in alfalfa sprouts, in Adelaide, Australia. In total, 31 cases of S. Havana were notified during June and July 2018 and linked to the outbreak. Eighteen cases and 54 unmatched controls were included in a case-control study. Results from the case-control study indicated an increased risk of illness linked to the consumption of alfalfa sprouts; this was supported by trace-back, sampling and environmental investigations. This outbreak of S. Havana was caused by consumption of alfalfa sprouts from one local sprouts producer. It is unclear as to when in the production of alfalfa sprouts the contamination occurred. However, contaminated seeds and poor pest control are the most likely causes. This investigation highlights the importance of ensuring that producers take appropriate action to minimise the likelihood of contamination and to comply with legislation and standards for primary production and food safety.

Shiga toxin producing Escherichia coli-associated diarrhea and hemolytic uremic syndrome in young children in Romania

Background

Diarrheagenic Escherichia coli (E. coli) is an important cause of diarrheal diseases in both developing countries and industrialized countries. An outbreak of hemolytic uremic syndrome (HUS) in young children from southern Romania was reported in early 2016 and was attributed to Shiga toxin producing E. coli (STEC) O26 infection. The aim of this study was to determine the prevalence, demographic and clinical characteristics of STEC infections in children hospitalized with diarrhea in Brașov in the central region of Romania. We also described the occurrence of HUS among hospitalized children, close in time to the 2016 HUS outbreak in southern Romania.

Methods

A prospective study was conducted between March and December 2016 among 722 children aged 1–30 months hospitalized with acute diarrhea. Stool samples obtained from patients with diarrhea were tested for the presence of Shiga toxin type 1 (STX1) and type 2 (STX2) by an immunochromatographic assay, and other enteropathogens. Demographic and clinical information on cases of HUS diagnosed in the same hospital was obtained from medical records.

Results

Overall 46/722 (6.4%) children (mean age 10.3 months, 32.6% females) hospitalized with diarrhea tested positive for STX1 or STX2; of these 79% were positive for both STX1 and STX2, 16% for STX2 only, and 5% for STX1 only. Bloody diarrhea, vomiting and fever were documented in 32.6%, 52.1% and 50.0%, respectively of patients with STEC infection. Eleven confirmed HUS cases (mean age 20 months, five females) were identified between 2014 and 2016 with prodromal diarrhea reported in 10 of them. Three of the 11 HUS patients required hemodialysis.

Conclusions

STEC prevalence among young children with diarrhea in Romania was high and the risk of HUS is emerging. The establishment of a systematic laboratory-based surveillance program including identification of the circulating STEC strains coupled with epidemiological investigation of HUS patients is warranted to determine the source and mode of transmission of STEC and prevent of STEC-associated diarrhea and HUS.

Whole-Genome-Based Public Health Surveillance of Less Common Shiga Toxin-Producing Escherichia coli Serovars and Untypeable Strains Identifies Four Novel O Genotypes

Shiga toxin-producing Escherichia coli (STEC) and the STEC subgroup enterohemorrhagic E. coli cause intestinal infections with symptoms ranging from watery diarrhea to hemolytic-uremic syndrome (HUS). A key tool for the epidemiological differentiation of STEC is serotyping. The serotype in combination with the main virulence determinants gives important insight into the virulence potential of a strain.

Shiga toxin-producing Escherichia coli (STEC) and the STEC subgroup enterohemorrhagic E. coli cause intestinal infections with symptoms ranging from watery diarrhea to hemolytic-uremic syndrome (HUS). A key tool for the epidemiological differentiation of STEC is serotyping. The serotype in combination with the main virulence determinants gives important insight into the virulence potential of a strain. However, a large fraction of STEC strains found in human disease, including strains causing HUS, belongs to less frequently detected STEC serovars or their O/H antigens are unknown or even untypeable. Recent implementation of whole-genome sequence (WGS) analysis, in principle, allows the deduction of serovar and virulence gene information. Therefore, here we compared classical serovar and PCR-based virulence marker detection with WGS-based methods for 232 STEC strains, focusing on less frequently detected STEC serovars and nontypeable strains. We found that the results of WGS-based extraction showed a very high degree of overlap with those of the more classical methods. Specifically, the rate of concordance was 97% for O antigens (OAGs) and 99% for H antigens (HAGs) of typeable strains and >99% for stx₁, stx₂, or eaeA for all strains. Ninety-eight percent of nontypeable OAGs and 100% of nontypeable HAGs were defined by WGS analysis. In addition, the novel methods enabled a more complete analysis of strains causing severe clinical symptoms and the description of four novel STEC OAG loci. In conclusion, WGS is a promising tool for gaining serovar and virulence gene information, especially from a public health perspective.

Clostridium perfringens enterotoxin-based protein engineering for the vaccine design and delivery system

Clostridium perfringens is a major cause of food poisoning worldwide, with its enterotoxin (CPE) being the major virulence factor. The C-terminus of CPE (C-CPE) is non-toxic and is the part of the toxin that binds to epithelial cells via the claudins in tight junctions; however, C-CPE has low antigenicity. To address this issue, we have used protein engineering technology to augment the antigenicity of C-CPE and have developed a C-CPE-based vaccine against C. perfringens-mediated food poisoning. Moreover, C-CPE has properties that make it potentially useful for the development of vaccines against other bacterial toxins that cause food poisoning. For example, we hypothesized that the ability of C-CPE to bind to claudins could be harnessed to deliver vaccine antigens directly to mucosa-associated lymphoid tissues, and we successfully developed a nasally administered C-CPE-based vaccine delivery system that promotes antigen-specific mucosal and systemic immune responses. In addition, our group has revealed the roles that the nasal mucus plays in lowering the efficacy of C-CPE-based nasal vaccines. Here, we review recent advances in the development of C-CPE-based vaccines against the major bacterial toxins that cause food poisoning and discuss our C-CPE-based nasal vaccine delivery system.

The Role of the AggR Regulon in the Virulence of the Shiga Toxin-Producing Enteroaggregative Escherichia coli Epidemic O104:H4 Strain in Mice

An O104:H4 Shiga toxin (Stx)-producing enteroaggregative Escherichia coli (EAEC) strain caused a large outbreak of bloody diarrhea and the hemolytic uremic syndrome in 2011. We previously developed an ampicillin (Amp)-treated C57BL/6 mouse model to measure morbidity (weight loss) and mortality of mice orally infected with the prototype Stx-EAEC strain C227-11. Here, we hypothesized that mice fed C227-11 cured of the pAA plasmid or deleted for individual genes on that plasmid would display reduced virulence compared to animals given the wild-type (wt) strain. C227-11 cured of the pAA plasmid or deleted for the known pAA-encoded virulence genes aggR, aggA, sepA, or aar were fed to Amp-treated C57BL/6 mice at doses of 10¹⁰–10¹¹CFU. Infected animals were then either monitored for morbidity and lethality for 28 days or euthanized to determine intestinal pathology and colonization levels at selected times. The pAA-cured, aggR, and aggA mutants of strain C227-11 all showed reduced colonization at various intestinal sites. However, the aggR mutant was the only mutant attenuated for virulence as it showed both reduced morbidity and mortality. The aar mutant showed increased expression of the aggregative adherence fimbriae (AAF) and caused greater systemic effects in infected mice when compared to the C227-11 wt strain. However, unexpectedly, both the aggA and aar mutants displayed increased weight loss compared to wt. The sepA mutant did not exhibit altered morbidity or mortality in the Amp-treated mouse model compared to wt. Our data suggest that the increased morbidity due to the aar mutant could possibly be via an effect on expression of an as yet unknown virulence-associated factor under AggR control.

QseC Signaling in the Outbreak O104:H4 Escherichia coli Strain Combines Multiple Factors during Infection

Enteroaggregative Escherichia coli (EAEC) from the O104:H4 specific serotype caused a large outbreak of bloody diarrhea with some complicated cases of hemolytic-uremic syndrome (HUS) in Europe in 2011. The outbreak strain consisted in an EAEC capable to produce the Shiga toxin (Stx) subtype 2a, a characteristic from enterohemorrhagic E. coli QseBC two-component system detects AI-3/Epi/NE and mediates the chemical signaling between pathogen and mammalian host. This system coordinates a cascade of virulence genes expression in important human enteropathogens. The blocking of QseC of EAEC C227-11 (Stx⁺) strain by N-phenyl-4-{[(phenylamino) thioxomethyl]amino}-benzenesulfonamide (also known as LED209) in vivo demonstrated a lower efficiency of colonization. The periplasmic protein VisP, which is related to survival mechanisms in a colitis model of infection, bacterial membrane maintenance, and stress resistance, here presented high levels of expression during the initial infection within the host. Under acid stress conditions, visP expression levels were differentiated in an Stx-dependent way. Together, these results emphasize the important role of VisP and the histidine kinase sensor QseC in the C227-11 (Stx⁺) outbreak strain for the establishment of the infectious niche process in the C57BL/6 mouse model and of LED209 as a promising antivirulence drug strategy against these enteric pathogens.IMPORTANCE EAEC is a remarkable etiologic agent of acute and persistent diarrhea worldwide. The isolates harbor specific subsets of virulence genes and their pathogenesis needs to be better understood. Chemical signaling via histidine kinase sensor QseC has been shown as a potential target to elucidate the orchestration of the regulatory cascade of virulence factors.

On the road to structure-based development of anti-virulence therapeutics targeting the type III secretion system injectisome

The type III secretion system injectisome is a syringe-like multimembrane spanning nanomachine that is essential to the pathogenicity but not viability of many clinically relevant Gram-negative bacteria, such as enteropathogenic Escherichia coli, Salmonella enterica and Pseudomonas aeruginosa. Due to the rise in antibiotic resistance, new strategies must be developed to treat the growing spectre of drug resistant infections. Targeting the injectisome via an 'anti-virulence strategy' is a promising avenue to pursue as an alternative to the more commonly used bactericidal therapeutics, which have a high propensity for resulting resistance development and often more broad killing profile, including unwanted side effects in eliminating favourable members of the microbiome. Building on more than a decade of crystallographic work of truncated or isolated forms of the more than two dozen components of the secretion apparatus, recent advances in the field of single-particle cryo-electron microscopy have allowed for the elucidation of atomic resolution structures for many of the type III secretion system components in their assembled, oligomerized state including the needle complex, export apparatus and ATPase. Cryo-electron tomography studies have also advanced our understanding of the direct pathogen-host interaction between the type III secretion system translocon and host cell membrane. These new structural works that further our understanding of the myriad of protein-protein interactions that promote injectisome function will be highlighted in this review, with a focus on those that yield promise for future anti-virulence drug discovery and design. Recently developed inhibitors, including both synthetic, natural product and peptide inhibitors, as well as promising new developments of immunotherapeutics will be discussed. As our understanding of this intricate molecular machinery advances, the development of anti-virulence inhibitors can be enhanced through structure-guided drug design.

Metagenomics for broad and improved parasite detection: a proof-of-concept study using swine faecal samples

Efficient and reliable identification of emerging pathogens is crucial for the design and implementation of timely and proportionate control strategies. This is difficult if the pathogen is so far unknown or only distantly related with known pathogens. Diagnostic metagenomics - an undirected, broad and sensitive method for the efficient identification of pathogens - was frequently used for virus and bacteria detection, but seldom applied to parasite identification. Here, metagenomics datasets prepared from swine faeces using an unbiased sample processing approach with RNA serving as starting material were re-analysed with respect to parasite detection. The taxonomic identification tool RIEMS, used for initial detection, provided basic hints on potential pathogens contained in the datasets. The suspected parasites/intestinal protists (Blastocystis, Entamoeba, Iodamoeba, Neobalantidium, Tetratrichomonas) were verified using subsequently applied reference mapping analyses on the base of rRNA sequences. Nearly full-length gene sequences could be extracted from the RNA-derived datasets. In the case of Blastocystis, subtyping was possible with subtype (ST)15 discovered for the first known time in swine faeces. Using RIEMS, some of the suspected candidates turned out to be false-positives caused by the poor status of sequences in publicly available databases. Altogether, 11 different species/STs of parasites/intestinal protists were detected in 34 out of 41 datasets extracted from metagenomics data. The approach operates without any primer bias that typically hampers the analysis of amplicon-based approaches, and allows the detection and taxonomic classification including subtyping of protist and metazoan endobionts (parasites, commensals or mutualists) based on an abundant biomarker, the 18S rRNA. The generic nature of the approach also allows evaluation of interdependencies that induce mutualistic or pathogenic effects that are often not clear for many intestinal protists and perhaps other parasites. Thus, metagenomics has the potential for generic pathogen identification beyond the characterisation of viruses and bacteria when starting from RNA instead of DNA.

Identification and characterization of atypical enteropathogenic and Shiga toxin-producing Escherichia coli isolated from ground beef and poultry breast purchased in Botucatu, Brazil

Atypical enteropathogenic (serotypes O4:H16, O8:H25, O68:H2, O105:H7, and OR:H25) and Shigatoxigenic (ONT:H46) Escherichia coli were isolated from samples of ground beef and poultry breast purchased in Botucatu, Brazil. Phenotypic and molecular characterization indicated the potential of these isolates to adhere to host epithelial cells and cause damage.

Guideline for the Antibiotic Use in Acute Gastroenteritis

Acute gastroenteritis is common infectious disease in community in adults. This work represents an update of 'Clinical guideline for the diagnosis and treatment of gastrointestinal infections' that was developed domestically in 2010. The recommendation of this guideline was developed regarding the following; epidemiological factors, test for diagnosis, the indications of empirical antibiotics, and modification of antibiotics after confirming pathogen. Ultimately, it is expected to decrease antibiotic misuse and prevent antibiotic resistance.

Anti-infective Properties of the Golden Spice Curcumin

The search for novel anti-infectives is one of the most important challenges in natural product research, as diseases caused by bacteria, viruses, and fungi are influencing the human society all over the world. Natural compounds are a continuing source of novel anti-infectives. Accordingly, curcumin, has been used for centuries in Asian traditional medicine to treat various disorders. Numerous studies have shown that curcumin possesses a wide spectrum of biological and pharmacological properties, acting, for example, as anti-inflammatory, anti-angiogenic and anti-neoplastic, while no toxicity is associated with the compound. Recently, curcumin’s antiviral and antibacterial activity was investigated, and it was shown to act against various important human pathogens like the influenza virus, hepatitis C virus, HIV and strains of Staphylococcus, Streptococcus, and Pseudomonas. Despite the potency, curcumin has not yet been approved as a therapeutic antiviral agent. This review summarizes the current knowledge and future perspectives of the antiviral, antibacterial, and antifungal effects of curcumin.

W. Vieira C, Parveen S. Genotypic and phenotypic characterization of Escherichia coli isolated from mollusks in Brazil and the United States

The aim of this study was to determine the serogroups, antimicrobial resistance and genetic diversity of Escherichia coli isolates from samples of bivalve mollusks collected along Santa Catarina coast, Brazil, and from the Chesapeake Bay, Maryland, USA. One hundred forty-one E. coli isolates were characterized for serogroups with 181 specific O antisera and antimicrobial susceptibility using the disk diffusion method. The genetic diversity was assessed using pulsed-field gel electrophoresis (PFGE). The results showed that among the isolates, 19.9% were classified as multi-drug resistant (MDR) and resistance was most frequently observed to cephalothin, nitrofurantoin, and ampicillin. The predominant serogroups were O6, O8, and O38. Some serogroups were recognized as pathogenic E. coli. PFGE dendrograms indicated extensive genetic diversity among the isolates. Although characteristics of the E. coli isolates were highly variable, it is important to note that E. coli belonging to pathogenic serogroups and MDR isolates are present in mollusks of both study areas. This is the first report on the phenotypic and genotypic characterization of E. coli from mollusks from Santa Catarina and the Chesapeake Bay that should encourage studies focusing on comparison of isolates across countries.

Gene duplications in the E. coli genome: common themes among pathotypes

Background

Gene duplication underlies a significant proportion of gene functional diversity and genome complexity in both eukaryotes and prokaryotes. Although several reports in the literature described the duplication of specific genes in E. coli, a detailed analysis of the extent of gene duplications in this microorganism is needed.

Results

The genomes of the E. coli enteroaggregative strain 042 and other pathogenic strains contain duplications of the gene that codes for the global regulator Hha. To determine whether the presence of additional copies of the hha gene correlates with the presence of other genes, we performed a comparative genomic analysis between E. coli strains with and without hha duplications. The results showed that strains harboring additional copies of the hha gene also encode the yeeR irmA (aec69) gene cluster, which, in turn, is also duplicated in strain 042 and several other strains. The identification of these duplications prompted us to obtain a global map of gene duplications, first in strain 042 and later in other E. coli genomes.

Duplications in the genomes of the enteroaggregative strain 042, the uropathogenic strain CFT073 and the enterohemorrhagic strain O145:H28 have been identified by a BLASTp protein similarity search. This algorithm was also used to evaluate the distribution of the identified duplicates among the genomes of a set of 28 representative E. coli strains. Despite the high genomic diversity of E. coli strains, we identified several duplicates in the genomes of almost all studied pathogenic strains. Most duplicated genes have no known function. Transcriptomic analysis also showed that most of these duplications are regulated by the H-NS/Hha proteins.

Conclusions

Several duplicated genes are widely distributed among pathogenic E. coli strains. In addition, some duplicated genes are present only in specific pathotypes, and others are strain specific. This gene duplication analysis shows novel relationships between E. coli pathotypes and suggests that newly identified genes that are duplicated in a high percentage of pathogenic E. coli isolates may play a role in virulence. Our study also shows a relationship between the duplication of genes encoding regulators and genes encoding their targets.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5683-4) contains supplementary material, which is available to authorized users.

Diarrhea-associated Hemolytic Uremic Syndrome in Adults: Two Case Reports and Review of the Literature

Hemolytic uremic syndrome (HUS) is a type of thrombotic microangiopathy syndrome (TMA) defined as a triad of non-immune microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Shiga toxin (Stx) or diarrhea-associated HUS is one of the major categories of secondary HUS, which is seen predominantly in children and is regarded as a rare entity in the adult population. We present two cases of sporadic Stx or diarrhea-associated HUS in adult females. Our first case is a 74-year-old Caucasian woman who presented to the emergency department with nausea, vomiting, and bloody diarrhea for five days. The patient reported a history of consuming meatloaf from a local store three days prior to the onset of symptoms. On presentation, laboratory workup was consistent with hemolytic anemia, thrombocytopenia, and acute kidney injury. Thrombocytopenic purpura was ruled out with normal ADAMTS13 activity. The patient’s kidney function improved and the platelet count recovered to normal with supportive measures and did not require renal replacement therapy. In the second case, we describe a 79-year-old Caucasian woman with a history of metastatic lung cancer who presented with abdominal pain, nausea, vomiting, and bloody diarrhea. History was positive for consuming meat from a local restaurant a day prior to the onset of symptoms. Initial laboratory work showed severe thrombocytopenia, microangiopathic hemolytic process, and acute kidney injury requiring continuous renal replacement therapy. Due to the unfavorable prognosis of her metastatic lung cancer, the patient and the family members decided to opt for hospice care and she was subsequently transferred to the inpatient hospice.

Diarrhea-associated HUS or Stx-HUS is a relatively underreported entity among the adult population. The treatment of typical or Stx-HUS is mainly supportive, but it is critical to rule out other causes of TMAs, especially thrombotic thrombocytopenic purpura (TTP), as it is a medical emergency that requires prompt plasmapheresis.

Roles of Shiga Toxins in Immunopathology

Shigella species and Shiga toxin-producing Escherichia coli (STEC) are agents of bloody diarrhea that may progress to potentially lethal complications such as diarrhea-associated hemolytic uremic syndrome (D+HUS) and neurological disorders. The bacteria share the ability to produce virulence factors called Shiga toxins (Stxs). Research over the past two decades has identified Stxs as multifunctional toxins capable of inducing cell stress responses in addition to their canonical ribotoxic function inhibiting protein synthesis. Notably, Stxs are not only potent inducers of cell death, but also activate innate immune responses that may lead to inflammation, and these effects may increase the severity of organ injury in patients infected with Stx-producing bacteria. In the intestines, kidneys, and central nervous system, excessive or uncontrolled host innate and cellular immune responses triggered by Stxs may result in sensitization of cells to toxin mediated damage, leading to immunopathology and increased morbidity and mortality in animal models (including primates) and human patients. Here, we review studies describing Stx-induced innate immune responses that may be associated with tissue damage, inflammation, and complement activation. We speculate on how these processes may contribute to immunopathological responses to the toxins.

Discovery of Shiga Toxin-Producing Escherichia coli (STEC)-Specific Bacteriophages From Non-fecal Composts Using Genomic Characterization

Composting is a complex biodegradable process that converts organic materials into nutrients to facilitate crop yields, and, if well managed, can render bactericidal effects. Majority of research focused on detection of enteric pathogens, such as Shiga toxin-producing Escherichia coli (STEC) in fecal composts. Recently, attention has been emphasized on bacteriophages, such as STEC-specific bacteriophages, associated with STEC from the fecal-contaminated environment because they are able to sustain adverse environmental condition during composting process. However, little is known regarding the isolation of STEC-specific bacteriophages in non-fecal composts. Thus, the objectives were to isolate and genomically characterize STEC-specific bacteriophages, and to evaluate its association with STEC in non-fecal composts. For bacteriophage isolation, the samples were enriched with non-pathogenic E. coli (3 strains) and STEC (14 strains), respectively. After purification, host range, plaque size, and phage morphology were examined. Furthermore, bacteriophage genomes were subjected to whole-genome sequencing using Illumina MiSeq and genomic analyses. Isolation of top six non-O157 and O157 STEC utilizing culture methods combined with PCR-based confirmation was also conducted. The results showed that various STEC-specific bacteriophages, including vB_EcoM-Ro111lw, vB_EcoM-Ro121lw, vB_EcoS-Ro145lw, and vB_EcoM-Ro157lw, with different but complementary host ranges were isolated. Genomic analysis showed the genome sizes varied from 42kb to 149kb, and most bacteriophages were unclassified at the genus level, except vB_EcoM-Ro111lw as FelixO1-like viruses. Prokka predicted less than 25% of the ORFs coded for known functions, including those essential for DNA replication, bacteriophage structure, and host cell lysis. Moreover, none of the bacteriophages harbored lysogenic genes or virulence genes, such as stx or eae. Additionally, the presence of these lytic bacteriophages was likely attributed to zero isolation of STEC and could also contribute to additional antimicrobial effects in composts, if the composting process was insufficient. Current findings indicate that various STEC-specific bacteriophages were found in the non-fecal composts. In addition, the genomic characterization provides in-depth information to complement the deficiency of biological features regarding lytic cycle of the new bacteriophages. Most importantly, these bacteriophages have great potential to control various serogroups of STEC.

Identifying the source of food-borne disease outbreaks: An application of Bayesian variable selection

Early identification of contaminated food products is crucial in reducing health burdens of food-borne disease outbreaks. Analytic case-control studies are primarily used in this identification stage by comparing exposures in cases and controls using logistic regression. Standard epidemiological analysis practice is not formally defined and the combination of currently applied methods is subject to issues such as response misclassification, missing values, multiple testing problems and small sample estimation problems resulting in biased and possibly misleading results. In this paper, we develop a formal Bayesian variable selection method to account for misclassified responses and missing covariates, which are common complications in food-borne outbreak investigations. We illustrate the implementation and performance of our method on a Salmonella Thompson outbreak in the Netherlands in 2012. Our method is shown to perform better than the standard logistic regression approach with respect to earlier identification of contaminated food products. It also allows relatively easy implementation of otherwise complex methodological issues.

Detection, Prevalence, and Pathogenicity of Non-O157 Shiga Toxin-Producing Escherichia coli from Cattle Hides and Carcasses

Cattle are a major reservoir for Shiga toxin-producing Escherichia coli (STEC) and harbor these bacteria in the intestinal tract. The prevalence, concentration, and STEC serogroup isolated in cattle varies between individuals. Hide removal at slaughter serves as a major point of carcass contamination and ultimately beef products. Certain STEC serogroups, such as O26, O45, O103, O111, O121, O145, and O157, containing the intestinal adherence factor intimin, pose a large economic burden to food producers because of testing and recalls. Human infection with STEC can cause illnesses ranging from diarrhea to hemorrhagic colitis and hemolytic uremic syndrome, and is commonly acquired through ingestion of contaminated foods, often beef products. Previously, most studies focused on O157 STEC, but there is growing recognition of the importance of non-O157 STEC serogroups. This review summarizes detection methods, prevalence, and methods for prediction of pathogenicity of non-O157 STEC from cattle hides and carcasses. A synthesis of procedures is outlined for general non-O157 STEC and targeted detection of specific STEC serogroups. Standardization of sample collection and processing procedures would allow for more robust comparisons among studies. Presence of non-O157 STEC isolated from cattle hides and carcasses and specific factors, such as point of sample collection and season, are summarized. Also, factors that might influence STEC survival on these surfaces, such as the microbial population on hides and microbial adherence genes, are raised as topics for future investigation. Finally, this review gives an overview on studies that have used genetic and cell-based methods to identify specific phenotypes of non-O157 STEC strains isolated from cattle to assess their risk to human health.

Shiga toxin triggers endothelial and podocyte injury: the role of complement activation

Shiga toxin (Stx)-producing Escherichia coli (STEC) is the offending agent in post-diarrhea-associated hemolytic uremic syndrome (HUS), a disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, and acute kidney failure, with thrombi occluding the renal microvasculature. Endothelial dysfunction has been recognized as the trigger event in the development of microangiopathic processes. Glomerular endothelial cells are susceptible to the toxic effects of Stxs that, via nuclear factor kappa B (NF-κB) activation, induce the expression of genes encoding for adhesion molecules and chemokines, culminating in leukocyte adhesion and platelet thrombus formation on the activated endothelium. Complement activation via the alternative pathway has been seen in patients during the acute phase of STEC-associated HUS. Experimental evidence has highlighted the role of complement proteins in driving glomerular endothelium toward a thrombogenic phenotype. At the glomerular level, podocytes are also an important target of Stx-induced complement activation. Glomerular injury as a consequence of podocyte dysfunction and loss is thus a mechanism that might affect long-term renal outcomes in the disease. New approaches to targeting the complement system may be useful therapeutic options for patients with STEC-HUS.

Inhibitory Effect of Lactic Acid Bacteria on Foodborne Pathogens: A Review

Foodborne pathogens are serious challenges to food safety and public health worldwide. Fermentation is one of many methods that may be used to inactivate and control foodborne pathogens. Many studies have reported that lactic acid bacteria (LAB) can have significant antimicrobial effects. The current review mainly focuses on the antimicrobial activity of LAB, the mechanisms of this activity, competitive growth models, and application of LAB for inhibition of foodborne pathogens.

Renal globotriaosylceramide facilitates tubular albumin absorption and its inhibition protects against acute kidney injury

To elucidate the physiologic function of renal globotriaosylceramide (Gb3/CD77), which up-to-date has been associated exclusively with Shiga toxin binding, we have analyzed renal function in Gb3-deficient mice. Gb3 synthase KO (Gb3S^-/-) mice displayed an increased renal albumin and low molecular weight protein excretion compared to WT. Gb3 localized at the brush border and within vesicular structures in WT proximal tubules and has now been shown to be closely associated with the receptor complex megalin/cubilin and with albumin uptake. In two clinically relevant mouse models of acute kidney injury caused by myoglobin as seen in rhabdomyolysis and the aminoglycoside gentamicin, Gb3S^-/- mice showed a preserved renal function and morphology, compared to WT. Pharmacologic inhibition of glucosylceramide-based glycosphingolipids, including Gb3, in WT mice corroborated the results of genetically Gb3-deficient mice. In conclusion, our data significantly advance the current knowledge on the physiologic and pathophysiologic role of Gb3 in proximal tubules, showing an involvement in the reabsorption of filtered albumin, myoglobin and the aminoglycoside gentamicin.

An Overview of Zoonotic Disease Outbreaks and its Forensic Management Over Time

Most emerging or re-emerging infections are vector-borne or zoonotic and can be disseminated worldwide by infected humans or animals. They are a major public health problem and cause a great impact on economy. Zoonotic outbreaks began to be characterized in the 90s, after the creation of Europol and the FBI. Such investigations are carried by forensic pathologists and other specialists to determine whether an outbreak is natural or deliberate. This review will discuss ten zoonotic outbreaks nonrelated to wars focusing on forensic management. In conclusion, some points should be highlighted in the management of a zoonotic outbreak: (i) its diagnosis and detection by forensic pathologists and the coordination of efforts between other specialists are key factors; (ii) communication guidelines and an efficient healthcare system are crucial for any emergency response; (iii) biosafety of all specialists involved must be guaranteed.

Emerging Point-of-care Technologies for Food Safety Analysis

Food safety issues have recently attracted public concern. The deleterious effects of compromised food safety on health have rendered food safety analysis an approach of paramount importance. While conventional techniques such as high-performance liquid chromatography and mass spectrometry have traditionally been utilized for the detection of food contaminants, they are relatively expensive, time-consuming and labor intensive, impeding their use for point-of-care (POC) applications. In addition, accessibility of these tests is limited in developing countries where food-related illnesses are prevalent. There is, therefore, an urgent need to develop simple and robust diagnostic POC devices. POC devices, including paper- and chip-based devices, are typically rapid, cost-effective and user-friendly, offering a tremendous potential for rapid food safety analysis at POC settings. Herein, we discuss the most recent advances in the development of emerging POC devices for food safety analysis. We first provide an overview of common food safety issues and the existing techniques for detecting food contaminants such as foodborne pathogens, chemicals, allergens, and toxins. The importance of rapid food safety analysis along with the beneficial use of miniaturized POC devices are subsequently reviewed. Finally, the existing challenges and future perspectives of developing the miniaturized POC devices for food safety monitoring are briefly discussed.

Shiga toxin-producing Escherichia coli in wild ungulates

Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens that live in the gastrointestinal tract of wildlife and cattle without causing disease. In humans, their colonization and infection lead to life-threatening disease. We investigated the occurrence of STEC in wild ungulates (wild boar, red deer and roe deer) inhabiting areas differently impacted by anthropogenic activities. STEC were detected in 9% (n = 6) of the samples and were recovered from the three species: 1 of wild boar, 4 of red deer and 1 of roe deer. All the isolates (n = 7) were non-O157 STEC encoding stx1 (n = 2; 29%) and/or stx2 genes (n = 6; 86%). O27:H30 was the most frequent serotype identified, followed by O146:H21 and O146:H28. Two STEC were O-untypable: ONT:H28 and ONT:H52. The phylo-groups identified were B1 (n = 3), E (n = 3) and F (n = 1). All the isolates recovered were susceptible to the different classes of antibiotics tested, although resistance genes were found in two strains. Apart from stx, all STEC encode many virulence factors (VF), particularly adhesins and/or other toxins. A strain with 13 VF collected from roe deer has a high enterohemorrhagic risk due to the presence of intimin, hemolysin and protease effectors genes. Enterohemorrhagic E. coli (EHEC) are implicated in the major cases of human infection and mortality, highlighting the zoonotic potential of wildlife-associated STEC. Wild ungulates are reservoirs of STEC potentially pathogenic to humans. Therefore, following the One Health concept, it is crucial to establish worldwide local monitoring programs that will benefit human, animal and environmental health.

Effects of Cultivating Years on Survival of Culturable Escherichia coli O157:H7 in Greenhouse Soils

The extent to how Escherichia coli O157:H7 can survive in soil and the predominant factors that determine its survival are crucial issues from a public health point of view. This study investigated the survival of E. coli O157:H7 in vegetable soils in plastic-greenhouse cultivation over 0, 1, 4, 8, and 12 years in southern China. Results showed that the survival times ( t_d) calculated from the Weibull model for the five tested soils ranged from 9.00 to 21.11 days. In general, E. coli O157:H7 survived longer in open-field soils than in greenhouse soils under the same incubation conditions. The t_d values were greater in soils with a lower level of electrical conductivity, a higher level of total nitrogen, and a higher level of sand content. Compared to other factors, electrical conductivity was the most important factor affecting the survival of E. coli O157:H7 in the tested soils. Different survival times of E. coli O157:H7 in vegetable soils under diverse cultivation patterns highlight the importance of preventing pathogenic contamination for the purpose of food safety.

Paediatric haemolytic uraemic syndrome related to Shiga toxin-producing Escherichia coli, an overview of 10 years of surveillance in France, 2007 to 2016

IntroductionHaemolytic uraemic syndrome (HUS) related to Shiga toxin-producing Escherichia coli (STEC) is the leading cause of acute renal failure in young children. In France, HUS surveillance in children aged < 15 years was implemented starting from 1996.AimWe present the results of this surveillance between 2007 and 2016.MethodsA voluntary nationwide network of 32 paediatric departments notifies cases. Two national reference centres perform microbiological STEC confirmation.ResultsOver the study period, the paediatric HUS incidence rate (IR) was 1.0 per 100,000 children-years, with a median of 116 cases/year. In 2011, IR peaked at 1.3 per 100,000 children-years, and decreased to 1.0 per 100,000 children-years in 2016. STEC O157 associated HUS peaked at 37 cases in 2011 and decreased to seven cases in 2016. Cases of STEC O26-associated HUS have increased since 2010 and STEC O80 associated HUS has emerged since 2012, with 28 and 18 cases respectively reported in 2016. Four STEC-HUS food-borne outbreaks were detected (three STEC O157 linked to ground beef and raw-milk cheese and one STEC O104 linked to fenugreek sprouts). In addition, two outbreaks related to person-to-person transmission occurred in distinct kindergartens (STEC O111 and O26).ConclusionsNo major changes in HUS IRs were observed over the study period of 10 years. However, changes in the STEC serogroups over time and the outbreaks detected argue for continuing epidemiological and microbiological surveillance.

An outbreak of hemolytic uremic syndrome in southern Romania during 2015-2016: Epidemiologic, clinical, laboratory, microbiologic, therapeutic and outcome characteristics

BACKGROUND AND AIMS

To describe the epidemiologic, clinical, microbiological, therapeutic and outcome characteristics of a HUS outbreak occurring in southern Romania from 2015 to 2016.

METHODS

We retrospectively collected data from the medical records of all HUS cases hospitalized at the pediatric nephrology department of Marie Curie Children's Hospital of Bucharest, Romania.

RESULTS

There were 32 HUS cases (19 girls/13 boys, 87.6% <2 years), all associated with diarrhea (bloody in 13, 40.6%). Thirteen (40.6%) and 4 (12.5%) patients had oliguria and anuria at admission. Extreme pallor, generalized edema, vomiting, dehydration, fever and seizures were found in 100%, 56.3%, 31.3%, 31.3%, 25% and 9.4% of patients, respectively. E. coli and STEC were identified in the stools of 6 and 8 patients, respectively; E. coli O₂₆ and O₁₅₇ infection were documented serologically in 10 and 3 children, respectively. There were 15/32 (46.9%) patients with confirmed HUS. Eighteen (56.3%) patients were hypertensive; other complications included infections, left ventricular hypertrophy, cardiopulmonary arrest, seizures and encephalopathy in 62.5%, 37.5%, 28.3%, 18.8% and 12.5%, respectively. Peritoneal dialysis and hemodialysis were performed in 23 (72%) and 2 patients, respectively. Three patients (9.4%) died early during hospitalization. A 6-12-month follow-up of 26 patients revealed that 65.4% had post-HUS sequelae (persistent hypertension and chronic renal failure in 34.6% and 30.8%, respectively).

CONCLUSIONS

The principal STEC serotype involved was O₂₆:H₁₁ and the number of confirmed HUS cases reached half of the patients. Compared with the medical literature, this outbreak had a higher rate of complications and renal sequelae and was associated with a high fatality rate.

Complement Activation Contributes to the Pathophysiology of Shiga Toxin-Associated Hemolytic Uremic Syndrome

Shiga toxin (Stx)-producing Escherichia coli (STEC) infections have become a threat to public health globally because of the severe illnesses that they can trigger, such as hemorrhagic colitis and the post-diarrheal hemolytic uremic syndrome (HUS), characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney failure. Glomerular endothelial cells are primary targets of Stx which, after binding to its specific receptor globotriaosylceramide, upregulates proinflammatory proteins involved both in the recruitment and adhesion of leukocytes and thrombus formation at the site of endothelial injury. In this review, we discuss the role of complement activation in promoting glomerular microvascular dysfunction, providing evidence from experimental models and patients with STEC-HUS. Within the glomerulus, an important target for Stx-induced complement activation is the podocyte, a cell type that is in close contact with endothelial cells and participates in maintaining the filtration barrier. Recently, podocyte injury and loss have been indicated as potential risk factors for long-term renal sequelae in patients with STEC-HUS. Therapeutic approaches targeting the complement system, that may be useful options for patients with STEC-HUS, will also be discussed.

Hidden Gems in the Transcriptome Maps of Competent Streptococci

Natural transformation is regarded as an important mechanism in bacteria that allows for adaptation to different environmental stressors by ensuring genome plasticity. Since the discovery of this phenomenon in Streptococcus pneumoniae, remarkable progress has been made in the understanding of the molecular mechanisms and pathways coordinating this process. Recently, the advent of high-throughput sequencing allows the posing of questions that address the system at a larger scale but also allow for the creation of high-resolution maps of transcription. Thus, while much is already known about genetic competence in streptococci, recent studies continue to reveal intricate novel regulation pathways and components. In this perspective article, we highlight the use of transcriptional profiling and mapping as a valuable resource in the identification and characterization of “hidden gems” pertinent to the natural transformation system. Such strategies have recently been employed in a variety of different species. In S. mutans, for example, genome editing combined with the power of promoter mapping and RNA-Seq allowed for the identification of a link between the ComCDE and the ComRS systems, a ComR positive feedback loop mediated by SigX, and the XrpA peptide, encoded within sigX, which inhibits competence. In S. pneumoniae, a novel member of the competence regulon termed BriC was found to be directly under control of ComE and to promote biofilm formation and nasopharyngeal colonization but not competence. Together these new technologies enable us to discover new links and to revisit old pathways in the compelling study of natural genetic transformation.

Risk of acquisition of human diarrhoeagenic Escherichia coli virulence genes in intercontinental travellers: A prospective, multi-centre study

BACKGROUND

We studied geographic distribution of diarrhoeagenic Escherichia coli virulence genes (DEC VGs) acquisition in travellers and investigated if they acquired highly virulent EAEC/STEC hybrid strains.

METHODS

From the prospective, multicentre COMBAT study among 2001 Dutch travellers, 491 travellers were selected based on travel destination to 7 subregions. Faecal samples taken directly before and after travel were screened for nine DEC VGs with real-time PCR. Incidence proportions and rates were calculated for each gene and subregion.

RESULTS

479 travellers were analysed. 21.8% acquired aggR (EAEC), with highest acquisition rates in Northern and Western Africa and 15.3% acquired eae (STEC/EPEC) with highest rates in travellers to Western and Eastern Africa. ETEC (elt or est gene) was acquired by 4.2% of travellers and acquisition of est was associated with traveller's diarrhoea. Overall, the risk of acquiring DEC VGs was low in Southern Africa and South America. Although the combination of aggR (EAEC) and stx1/2 (STEC) was acquired by 3 travellers, these genes could not be detected together in a single E. coli strain.

CONCLUSIONS

The risk of acquisition of DEC VGs strongly depends on the travel destination, with those travelling to Africa - except Southern Africa - having a higher risk.

Clinical application of bacteriophages in Europe

Bacteriophages could help address the antibiotic resistance crisis that impacts health systems all over the world. In 2011, the European Commission formally confirmed that phage products used as therapeutics are medicinal products and thus manufacturers need to navigate the extremely arduous and enormously expensive medicine development and marketing pathway. However, up until now, not one therapeutic phage product has made it to the European market, and yet clinicians are under increasing pressure to use phages in the treatment of multidrug-resistant bacterial infections. While a handful of small European enterprises are struggling to squeeze therapeutic phage products through the conventional and centralised European medicinal products funnel, some clinicians and academics are exploring (European) national solutions to accelerate the availability of phages for the treatment of an increasing number of desperate patients. This mini-review summarises the actual status and perspectives of clinical phage application in Europe.

Organization and architecture of AggR-dependent promoters from enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAEC), is a diarrhoeagenic human pathogen commonly isolated from patients in both developing and industrialized countries. Pathogenic EAEC strains possess many virulence determinants, which are thought to be involved in causing disease, though, the exact mechanism by which EAEC causes diarrhoea is unclear. Typical EAEC strains possess the transcriptional regulator, AggR, which controls the expression of many virulence determinants, including the attachment adherence fimbriae (AAF) that are necessary for adherence to human gut epithelial cells. Here, using RNA‐sequencing, we have investigated the AggR regulon from EAEC strain 042 and show that AggR regulates the transcription of genes on both the bacterial chromosome and the large virulence plasmid, pAA2. Due to the importance of fimbriae, we focused on the two AAF/II fimbrial gene clusters in EAEC 042 (afaB‐aafCB and aafDA) and identified the promoter elements and AggR‐binding sites required for fimbrial expression. In addition, we examined the organization of the fimbrial operon promoters from other important EAEC strains to understand the rules of AggR‐dependent activation. Finally, we generated a series of semi‐synthetic promoters to define the minimal sequence required for AggR‐mediated activation and show that the correct positioning of a single AggR‐binding site is sufficient to confer AggR‐dependence.

Novel type of pilus associated with a Shiga-toxigenic E. coli hybrid pathovar conveys aggregative adherence and bacterial virulence

A large German outbreak in 2011 was caused by a locus of enterocyte effacement (LEE)-negative enterohemorrhagic E. coli (EHEC) strain of the serotype O104:H4. This strain harbors markers that are characteristic of both EHEC and enteroaggregative E. coli (EAEC), including aggregative adhesion fimbriae (AAF) genes. Such rare EHEC/EAEC hybrids are highly pathogenic due to their possession of a combination of genes promoting severe toxicity and aggregative adhesion. We previously identified novel EHEC/EAEC hybrids and observed that one strain exhibited aggregative adherence but had no AAF genes. In this study, a genome sequence analysis showed that this strain belongs to the genoserotype O23:H8, MLST ST26, and harbors a 5.2 Mb chromosome and three plasmids. One plasmid carries some EAEC marker genes, such as aatA and genes with limited protein homology (11–61%) to those encoding the bundle-forming pilus (BFP) of enteropathogenic E. coli. Due to significant protein homology distance to known pili, we designated these as aggregate-forming pili (AFP)-encoding genes and the respective plasmid as pAFP. The afp operon was arranged similarly to the operon of BFP genes but contained an additional gene, afpA2, which is homologous to afpA. The deletion of the afp operon, afpA, or a nearby gene (afpR) encoding an AraC-like regulator, but not afpA2, led to a loss of pilin production, piliation, bacterial autoaggregation, and importantly, a >80% reduction in adhesion and cytotoxicity toward epithelial cells. Gene sets similar to the afp operon were identified in a variety of aatA-positive but AAF-negative intestinal pathogenic E. coli. In summary, we characterized widely distributed and novel fimbriae that are essential for aggregative adherence and cytotoxicity in a LEE-negative Shiga-toxigenic hybrid.

Hemolytic Uremic Syndrome Associated With Escherichia coli O157 Infection in an Allogenic Stem Cell Transplant Recipient

We report the development of a Shiga toxin-producing Escherichia coli O157 gastrointestinal infection associated with hemolytic uremic syndrome in an allogenic stem cell transplant recipient with a history of gastrointestinal graft-vs-host disease receiving long-term immunosuppression.

Outbreak of Shiga toxin-producing Escherichia-coli-associated hemolytic uremic syndrome in Istanbul in 2015: outcome and experience with eculizumab

BACKGROUND

This study aims to identify epidemiological and clinical characteristics of patients and report our experience with eculizumab treatment during an outbreak of hemolytic uremic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC) in Istanbul in 2015.

METHODS

Thirty-two children (21 females, median age 3.25 years) were included in this study. Demographic, clinical and laboratory data, and treatment details were retrospectively collected. Renal outcomes were assessed at last follow-up visit. To assess the effect of eculizumab on prognosis of STEC-HUS, subgroup analysis was performed on patients who required dialysis.

RESULTS

A high number of cases occurred within a certain region of Istanbul. Stool samples were cultured from 21 patients (65%), and enteroaggregative E. coli (EAEC; n = 7) and enterohemorrhagic E. coli (EHEC; n = 3) strains were detected. Rates of dialysis treatment, neurological manifestations, and death were 59%, 25%, and 3%, respectively. Mean follow-up duration was 8.6 ± 2.6 months (range 3-12 months). None of the patients (n = 25) was on dialysis at the final visit. The complete renal recovery rate was 54%. Nine patients were treated with eculizumab. At final follow-up visit, no differences in estimated glomerular filtration rate, proteinuria level, or hypertension incidence were observed between patients treated with eculizumab and those not treated with eculizumab.

CONCLUSIONS

An outbreak of EAEC occurred in a specific region of Istanbul. Livestock markets were suspected as the source. Evidence for beneficial effects of eculizumab on renal outcome was not clear in this cohort.

Investigations by the Institut Hospitalo-Universitaire Méditerranée Infection of food and food-borne infections in the Mediterranean Basin and in sub-Saharan Africa

Food-borne infections are major causes of public health concern in developing and developed countries. During the past decade, the Institut Hospitalo-Universitaire Méditerranée Infection has conducted or been involved in multiple investigations that aimed at identifying the sources and strains responsible for food-borne diseases and therefore at improving the understanding, diagnosis, prevention and control of these infections. Investigations were conducted in the Mediterranean area and in sub-Saharan Africa on more than 15 food-borne agents, 17 food products and 14 antibiotic resistance-associated genes. Multiple sources, including unexpected ones, and pathogens, including emerging ones, were involved. Travelling in developing countries and zoonoses are major contributors to food-borne infections, while food-borne transmission of resistance-associated genes is increasingly reported. However, risk factors and pathogens associated with food-borne infections likely remain untapped and must be more extensively investigated, monitored and regularly reassessed. Diagnostic tests based on new technologies and real-time surveillance tools based on microbiology laboratory data are promising approaches to detect known food-borne infections and decipher new ones. Studies of the microbiota and its relationships with dietary patterns are also worth being conducted.