Serogroup O157 Research Articles

Caracterización molecular de aislamientos de Escherichia coli productores de toxina Shiga obtenidos en 2 establecimientos ganaderos del Paraguay

Shiga toxin-producing Escherichia coli (STEC) is a food-borne pathogen in humans, with cattle being the main reservoir. The objective of this study was to determine the carrying of STEC in Paraguayan bovines and to analyze the virulence profile and serotypes of these isolates. A total of 197 samples of bovine fecal samples and an average of 5 to 50 colonies from stx1/stx2 positive samples were studied. The stx1, stx2, saa, ehxA and eae genes were amplified by PCR. 84.8% of the cattle were carriers of STEC. The predominant virulence profiles were stx2 and stx2/saa/ehxA. The serotyping was performed by agglutination reactions for 60 selected isolates, resulting in isolation of serogroup O103, which could produce infections in humans. This work shows the first data of STEC carriers in Paraguayan cattle, and indicates the need for other studies with greater territorial coverage for a complete vision of this phenomenon.

Eleven High-Quality Reference Genome Sequences and 360 Draft Assemblies of Shiga Toxin-Producing Escherichia coli Isolates from Human, Food, Animal, and Environmental Sources in Canada.

We report high-quality closed reference genomes for 1 bovine strain and 10 human Shiga toxin (Stx)-producing Escherichia coli (STEC) strains from serogroups O26, O45, O91, O103, O104, O111, O113, O121, O145, and O157. We also report draft assemblies, with standardized metadata, for 360 STEC strains isolated from watersheds, animals, farms, food, and human infections.

Shiga toxin-producing Escherichia coli in British Columbia, 2011-2017: Analysis to inform exclusion guidelines.

Shiga toxin-producing Escherichia coli (STEC) can cause severe illness including bloody diarrhea and hemolytic-uremic syndrome (HUS) through the production of Shiga toxins 1 (Stx1) and 2 (Stx2). E. coli O157:H7 was the most common serotype detected in the 1980s to 1990s, but improvements in laboratory methods have led to increased detection of non-O157 STEC. Non-O157 STEC producing only Stx1 tend to cause milder clinical illness. Exclusion guidelines restrict return to high-risk work or settings for STEC cases, but most do not differentiate between STEC serogroups and Stx type. To analyze British Columbia (BC) laboratory and surveillance data to inform the BC STEC exclusion guideline. For all STEC cases reported in BC in 2011-2017, laboratory and epidemiological data were obtained through provincial laboratory and reportable disease electronic systems, respectively. Incidence was measured for all STEC combined as well as by serogroup. Associations were measured between serogroups, Stx types and clinical outcomes. Over the seven year period, 984 cases of STEC were reported. A decrease in O157 incidence was observed, while non-O157 rates increased. The O157 serogroup was significantly associated with Stx2. Significant associations were observed between Stx2 and bloody diarrhea, hospitalization and HUS. The epidemiology of STEC has changed in BC as laboratories increasingly distinguish between O157 and non-O157 cases and identify Stx type. It appears that non-O157 cases with Stx1 are less severe than O157 cases with Stx2. The BC STEC exclusion guidelines were updated as a result of this analysis.

Molecular profiling and antimicrobial resistance of Shiga toxin-producing Escherichia coli O26, O45, O103, O121, O145 and O157 isolates from cattle on cow-calf operations in South Africa

In this study, 140 cattle STEC isolates belonging to serogroups O157, O26, O145, O121, O103 and O45 were characterized for 38 virulence-associated genes, antimicrobial resistance profiles and genotyped by PFGE. The majority of isolates carried both stx1 and stx2 concurrently, stx2c, and stx2d; plasmid-encoded genes ehxA, espP, subA and saa but lacked katP and etpD and eaeA. Possession of eaeA was significantly associated with the presence of nle genes, katP, etpD, ureC and terC. However, saa and subA, stx1c and stx1d were only detected in eaeA negative isolates. A complete OI-122 and most non-LEE effector genes were detected in only two eaeA positive serotypes, including STEC O157:H7 and O103:H2. The eaeA gene was detected in STEC serotypes that are commonly implicated in severe humans disease and outbreaks including STEC O157:H7, STEC O145:H28 and O103:H2. PFGE revealed that the isolates were highly diverse with very low rates of antimicrobial resistance. In conclusion, only a small number of cattle STEC serotypes that possessed eaeA, had the highest number of virulence-associated genes, indicative of their high virulence. Further characterization of STEC O157:H7, STEC O145:H28 and O103:H2 using whole genome sequencing will be needed to fully understand their virulence potential for humans.

Standardization of a multiplex PCR technique for the detection of Shiga toxin-producing Escherichia coli (STEC) serogroups O157, O104 and "big six"

Los serogrupos O26, O45, O103, O104, O111, O121, O145 y O157 de STEC se relacionan con un elevado numero de casos de SUH a nivel mundial, por lo que estan incluidos dentro de las categorias de mayor riesgo para los humanos, segun los criterios de autoridades alimentarias de Estados Unidos y Europa. El metodo convencional de identificacion de antigenos O y H se realiza por aglutinacion con antisueros de conejo. Este metodo ademas de ser muy costoso y laborioso, no se encuentra disponible en el pais para empleo masivo. En este contexto, el objetivo de este estudio observacional descriptivo de corte transverso ha sido la estandarizacion de una tecnica de PCR multiple para la deteccion de estos 8 serogrupos, a fin de contar con un sistema de deteccion eficiente, sensible y con potencial de aplicacion en la industria alimentaria. Se estandarizaron reacciones de PCR empleando como controles positivos cepas E. coli de referencia correspondientes a la totalidad de los serogrupos citados. Se obtuvieron productos de tamanos esperados para cada serogrupo, no se observaron amplificaciones cruzadas o falsos positivos. Esta tecnica estandarizada podria representar una herramienta rapida y menos costosa que la tecnica serologica, con la capacidad de ser aplicada a diferentes matrices, permitiendo la deteccion de estos serogrupos en aislados STEC de ganado en pie, fuentes de agua de consumo, alimentos e incluso en aislamientos clinicos asociados a enfermedades humanas.

Isolation and characterisation of Shiga toxin-producing Escherichia coli from Norwegian bivalves

Only a few studies concerning Shiga toxin-producing E. coli (STEC) detection in bivalves and their harvesting areas have been reported, and to the best of our knowledge there are no outbreaks associated with STEC from bivalves described. The aim of the present study was to investigate the occurrence of STEC in Norwegian bivalves, and to characterize potential STEC isolated from the samples. A total of 269 samples of bivalves were screened for the presence of stx and eae genes, and markers for the serogroups O26, O103, O111, O145 and O157 by using ISO TS 13136 (2012). The screening returned 19 samples that were positive for stx and eae, and attempts of isolation of STEC were made from these samples. Presumptive STEC were obtained from three samples, and three isolates (one from each sample) were subjected to whole-genome-sequencing (WGS). The WGS revealed that one of the isolates did not carry the stx genes, while the other two were identified as stx2i positive E. coli O9:H19 and stx2g positive E. coli O96:H19. Neither of the two STEC isolates were positive for virulence markers such as eae and ehx. The results suggest that the occurrence of STEC in Norwegian bivalves is low.

A sensitive method for the recovery of Escherichia coli serogroup O55 including Shiga toxin-producing variants for potential use in outbreaks.

AimShiga toxin‐producing Escherichia coli (STEC) cause bloody diarrhoea, kidney failure and occasionally death. However, identifying the source of infection caused by STEC other than serogroup O157 is hampered by the availability of sensitive methods for detecting these pathogens. In this study, we developed novel tools for detecting E. coli O55 that is potentially associated with human outbreaks.Methods and ResultsOverall specificity of immuno‐magnetic separation (IMS) beads coated with anti‐O55 serum was good with exception of cross‐reactivity with E. coli O22 and O23, which was eliminated using an O55‐specific PCR. Limit of detection for E. coli O55 using O55‐IMS beads in spiked cattle faeces was on average 50 CFU per ml (range 1–90), and improved to <10 CFU per ml using the O55‐specific PCR, following IMS on samples enriched for 2 h with E. coli O55. Application of these tools to test cattle faeces collected on‐farm allowed the isolation of O55:H19, which through whole genome sequencing was compared to STEC O55:H7 human outbreak strains.ConclusionThese tools provide a sensitive method which could be used to screen samples for STEC O55, whether environmental or human clinical.Significance and Impact of the StudySeveral human outbreaks reported in England were caused by STEC O55:H7. Tools developed here could assist in identification of the environmental source for these isolates, which has not yet been established.

Interactions of Carvacrol, Caprylic Acid, Habituation, and Mild Heat for Pressure-Based Inactivation of O157 and Non-O157 Serogroups of Shiga Toxin-Producing Escherichia coli in Acidic Environment.

The current study investigated synergism of elevated hydrostatic pressure, habituation, mild heat, and antimicrobials for inactivation of O157 and non-O157 serogroups of Shiga toxin-producing Escherichia coli. Various times at a pressure intensity level of 450 MPa were investigated at 4 and 45 °C with and without carvacrol, and caprylic acid before and after three-day aerobic habituation in blueberry juice. Experiments were conducted in three biologically independent repetitions each consist of two replications and were statistically analyzed as a randomized complete block design study using ANOVA followed by Tukey- and Dunnett’s-adjusted mean separations. Under the condition of this experiment, habituation of the microbial pathogen played an influential (p < 0.05) role on inactivation rate of the pathogen. As an example, O157 and non-O157 serogroups were reduced (p < 0.05) by 1.4 and 1.6 Log CFU/mL after a 450 MPa treatment at 4 °C for seven min, respectively, before habituation. The corresponding log reductions (p < 0.05) after three-day aerobic habituation were: 2.6, and 3.3, respectively at 4 °C. Carvacrol and caprylic acid addition both augmented the pressure-based decontamination efficacy. As an example, Escherichia coli O157 were reduced (p < 0.05) by 2.6 and 4.2 log CFU/mL after a seven-min treatment at 450 MPa without, and with presence of 0.5% carvacrol, respectively, at 4 °C.

Diagnostic bacteriophage V32 as a tool for the rapid identification of Escherichia coli serogroup O157.

Bacteriophage V32, a representative of bacterial viruses of the Myoviridae family Ounavirinae subfamily, is proposed for search and identification of E. coli O157 serogroup, including Shiga-toxin producing E. coli O157:H7 (STEC O157:H7), among cultures of enterobacteria from the primary seeding of the material studied. Phage genome containes a linear double-stranded DNA of 87875 base pairs with G/C-content of 38.9% and includes 132 open reading frames (ORF). In the genome, there are no determinants of antibiotic resistance, virulence genes of STEC and other well-known pathogroups of E. coli. It has been established that phage V32 has lytic activity against all studied cultures of E. coli O157 serogroup (n=183) isolated from people and farm animals in various regions of the Russian Federation, as well as in Japan and Italy. At the same time, the phage lyses only 6 of 182 strains (3.3%) of E. coli not belonging to the O157 serogroup and is not active against strains of other enterobacteria. That is, the phage has a high specificity. The use of bacteriophage V32 as a diagnostic tool is a highly efficient, fast, cheap and simple method for identifying E. coli serogroup O157, including the serotype E. coli O157: H7, in any bacteriological laboratory without special equipment and special training of performers.

The epidemiology of Shiga toxin-producing Escherichia coli infections in the South East of England: November 2013–March 2017 and significance for clinical and public health

This study describes the epidemiology of Shiga toxin-producing Escherichia coli (STEC) infections in a population in the South East of England. From 1 November 2013 to 31 March 2017 participating diagnostic laboratories reported Shiga toxin gene (stx) positive real-time PCR results to local public health teams. Stx positive faecal samples/isolates were referred to the Gastrointestinal Bacteria Reference Unit (GBRU) for confirmation by culture and typing by whole genome sequencing (WGS). Key clinical information was collected by public health teams.Results/Key findings. Altogether, 548 faecal specimens (420 were non-travel associated) were stx positive locally, 535 were submitted to the GBRU. STEC were isolated from 42 %, confirmed by stx PCR in 21 % and 37 % were PCR negative. The most common non-travel associated STEC serogroups were O157, O26, O146 and O91. The annualized incidence of confirmed STEC infections (PCR or culture) was 5.8 per 100 000. The ratio of O157 to non-O157 STEC serogroups was 1:7. The annualized incidence of non-O157 haemolytic uraemic syndrome-associated Escherichia coli (HUSEC) strains was 0.4 per 100 000. Bloody diarrhoea was reported by 58 % of cases infected with E. coli O157, 33 % of cases infected with non-O157 HUSEC strains and 12 % of other lower risk non-O157 strains. Overall, 76 % of non-O157 HUSEC isolates possessed the eae virulence gene. HUSEC including serogroup O157 were uncommon and more likely to cause bloody diarrhoea than other STEC. The routine use of stx PCR testing can influence clinical management. Understanding the local epidemiology facilitates a proportionate public health response to STEC, based on clinical and microbiological characteristics including stx subtype(s).

Survival of acid-adapted and non-adapted Shiga toxin-producing Escherichia coli using an in vitro model

Shiga toxin-producing Escherichia coli (STEC) are known to adapt and survive acidic conditions. Acid-adaptation also may result in cross-protection against other stressors present in foods, such as reduced water activity (aw), refrigeration conditions, or the presence of antimicrobials. Three independent experiments were conducted with non-adapted (control) and acid-adapted E. coli O157:H7 and non-O157:H7 serogroups (E. coli O26, O45, O103, O111, O121 and O145) in vitro and in situ. Experiment 1: STEC cocktails in media were left untreated (non-adapted; control) or adapted (pH 5.0), exposed to mild acidic conditions (pH 4.5) or reduced aw (0.88 and 0.75) for 4 days at 24 °C, and evaluated for survival. Experiment 2: Non-adapted and acid-adapted STEC cocktails were subjected to desiccation (28 days at 24 °C) on sterile paper disks, and remaining pathogen populations were determined. Experiment 3: Control and acid-adapted STEC were subjected to mild acidic conditions (pH 4.5) and low aw (0.88 or 0.78) in ground beef slurries (GBS; 4 days at 24 °C) and surviving populations enumerated. Results from experiment 1 demonstrated that populations of non-O157:H7 STEC serogroups O45, O103, O111 and O121 were significantly different from populations of E. coli O157:H7, and non-O157:H7 STEC serogroups O26 and O145. In contrast, when STEC serogroups were acid-adapted, all populations of non-O157:H7 STEC were significantly different from populations of E. coli O157:H7. Results of experiments in media with aw of 0.88 or 0.78 demonstrated that there was no significant difference between E. coli O157:H7 and any of the non-O157:H7 STEC, regardless of acid-adaptation. In experiment 2, exposure to desiccation resulted in no significant difference in survival between E. coli O157:H7 and non-O157:H7 STEC, regardless of acid-adaptation. Experiment 3 in acidified GBS demonstrated that all non-O157:H7 STEC behaved similarly to E. coli O157:H7, except for E. coli O145, which had a higher reduction than O157:H7. There were no significant differences in bacterial populations associated with GBS with modified aw. Collectively, these results suggest than non-O157:H7 STEC behave similarly to E. coli O157:H7 when exposed to low pH (<4.5) and low aw (0.88 or 0.78) under laboratory conditions.

Biofilm Formation by Shiga Toxin-Producing Escherichia coli on Stainless Steel Coupons as Affected by Temperature and Incubation Time.

Forming biofilm is a strategy utilized by Shiga toxin-producing Escherichia coli (STEC) to survive and persist in food processing environments. We investigated the biofilm-forming potential of STEC strains from 10 clinically important serogroups on stainless steel at 22 °C or 13 °C after 24, 48, and 72 h of incubation. Results from crystal violet staining, plate counts, and scanning electron microscopy (SEM) identified a single isolate from each of the O113, O145, O91, O157, and O121 serogroups that was capable of forming strong or moderate biofilms on stainless steel at 22 °C. However, the biofilm-forming strength of these five strains was reduced when incubation time progressed. Moreover, we found that these strains formed a dense pellicle at the air-liquid interface on stainless steel, which suggests that oxygen was conducive to biofilm formation. At 13 °C, biofilm formation by these strains decreased (P < 0.05), but gradually increased over time. Overall, STEC biofilm formation was most prominent at 22 °C up to 24 h. The findings in this study identify the environmental conditions that may promote STEC biofilm formation in food processing facilities and suggest that the ability of specific strains to form biofilms contributes to their persistence within these environments.

Use of Genomics to Investigate Historical Importation of Shiga Toxin-Producing Escherichia coli Serogroup O26 and Nontoxigenic Variants into New Zealand.

Shiga toxin–producing Escherichia coli serogroup O26 is an important public health pathogen. Phylogenetic bacterial lineages in a country can be associated with the level and timing of international imports of live cattle, the main reservoir. We sequenced the genomes of 152 E. coli O26 isolates from New Zealand and compared them with 252 E. coli O26 genomes from 14 other countries. Gene variation among isolates from humans, animals, and food was strongly associated with country of origin and stx toxin profile but not isolation source. Time of origin estimates indicate serogroup O26 sequence type 21 was introduced at least 3 times into New Zealand from the 1920s to the 1980s, whereas nonvirulent O26 sequence type 29 strains were introduced during the early 2000s. New Zealand’s remarkably fewer introductions of Shiga toxin–producing Escherichia coli O26 compared with other countries (such as Japan) might be related to patterns of trade in live cattle.

DNA Microarray-Based Genomic Characterization of the Pathotypes of Escherichia coli O26, O45, O103, O111, and O145 Isolated from Feces of Feedlot Cattle

Shiga toxin-producing Escherichia coli (STEC) serogroups O26, O45, O103, O111, O121, and O145, referred to as the top six non-O157 serogroups, are responsible for more than 70% of human non-O157 STEC infections in North America. Cattle harbor non-O157 strains in the hindgut and shed them in the feces. The objective of this study was to use the U.S. Food and Drug Administration (FDA) E. coli identification (ECID) DNA microarray to identify the serotype, assess the virulence potential of each, and determine the phylogenetic relationships among five of the six non-O157 E. coli serogroups isolated from feedlot cattle feces. Forty-four strains of STEC, enterohemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC), or putative nonpathotype E. coli (NPEC) of cattle origin and five human clinical strains of EHEC were assayed with the FDA-ECID DNA microarray. The cattle strains harbored diverse flagellar genes. The bovine and human strains belonging to serogroups O26, O45, and O103 carried stx1 only, O111 carried both stx1 and stx2, and O145 carried either stx1 or stx2. The strains were also positive for various subtypes of intimin and other adhesins (IrgA homologue adhesin, long polar fimbriae, mannose-specific adhesin, and curli). Both human and cattle strains were positive for LEE-encoded type III secretory system genes and non-LEE-encoded effector genes. SplitsTree4, a program used to determine the phylogenetic relationship among the strains, revealed that the strains within each serogroup clustered according to their pathotype. In addition to genes encoding Shiga toxins, bovine non-O157 E. coli strains possessed other major virulence genes, including those for adhesins, type III secretory system proteins, and plasmid-borne virulence genes, similar to human clinical strains. Because virulence factors encoded by these genes are involved in the pathogenesis of various pathotypes of E. coli, the bovine non-O157 strains could cause human illness. The FDA-ECID DNA microarray assay rapidly provided a profile of the virulence genes for assessment of the virulence potential of each strain.

Surveillance of Shiga-toxin producing Escherichia coli in Irish sheep

Shiga-toxin producing Escherichia coli (STEC) is a foodborne zoonotic pathogen of significant public health concern. Ruminant animals are considered the primary reservoir of STEC. STEC predominantly colonises the lower gastro-intestinal tract, termed the recto-anal junction (RAJ). The number of STEC shed in the faeces of ruminants can vary widely with some animals, termed ‘super-shedders’ (>Log104 c.f.u. g−1 faeces), high risk carriers of the pathogen. The objective of this study was to sample a large cohort of Irish sheep, with quantitative and qualitative analysis of each sample for STEC. RAJ swab samples (N=410) were collected over a 9 month period from an ovine slaughtering facility. Each swab was enriched in 30 ml of modified Tryptone Soya Broth with Novobiocin at 41.5 °C for 5 h and subjected to a quantitative real-time PCR assay to detect and enumerate serogroups O157 and O26 in super-shedding animals. Incubation was allowed to continue for 24 h and shiga-toxin prevalence was assessed using a targeted qualitative real-time PCR assay. Eight O157 strains were isolated, of which six were super-shedding strains. The incidence of stx, O157 and O26 positive swabs was 49.3 %, 1.95 % and 0.24 % respectively. The prevalence of stx1, stx2 and stx1/stx2 virulence factors in isolated strains was 15.9 %, 8.8 % and 22.4 %. Additionally, the occurrence of stx1/stx2 in combination with eaeA in strains was found to be significant according to Pearson’s correlation and a paired T-test. In conclusion, these results underline the risk Irish sheep pose as a potential source of STEC infection.

Salmonella and Enterohemorrhagic Escherichia coli Serogroups O45, O121, O145 in Wheat Flour: Effects of Long-Term Storage and Thermal Treatments.

Salmonella and enterohemorrhagic Escherichia coli (EHEC) are of serious concern in wheat flour and its related products but little is known on their survival and thermal death kinetics. This study was undertaken to determine their long-term viability and thermal inactivation kinetics in flour. Inoculation was performed using mixtures of EHEC serogroups O45, O121, O145 and Salmonella followed by storage at room temperature (23°C) or 35°C (for Salmonella). Plate counting on tryptic soy agar (TSA) and enrichment were used to assess long-term survival. For thermal studies, wheat flour samples were heated at 55, 60, 65, and 70°C and cell counts of EHEC and Salmonella were determined by plating. The δ-values were calculated using the Weibull model. At room temperature, EHEC serovars and Salmonella were quantifiable for 84 and 112 days, and were detectable for the duration of the experiment after 168 and 365 days, respectively. The δ-values were 2.0, 5.54, and 9.3 days, for EHEC O121, O45, and O145, respectively, and 9.7 days for Salmonella. However, the only significant difference among all values was the δ-value for Salmonella and serogroup O121 (p ≤ 0.05). At 35°C, Salmonella counts declined to unquantifiable levels after a week and were not detected upon enrichment after 98 days. Heat treatment of inoculated wheat flour at 55, 60, 65, and 70°C resulted in δ-value ranges of 20.0–42.9, 4.9–10.0, 2.4–3.2, and 0.2–1.6 min, respectively, for EHEC. The δ-values for Salmonella at those temperatures were 152.2, 40.8, 17.9, and 17.4 min, respectively. The δ-values obtained for Salmonella at each temperature were significantly longer than for EHEC (p ≤ 0.05). Weibull model was a good fit to describe the thermal death kinetics of Salmonella and EHEC O45, O121 and O145 in wheat flour.HIGHLIGHTS -EHEC and Salmonella can survive for extended periods of time in wheat flour.-Long-term storage inactivation curves of EHEC and Salmonella were similar.-EHEC was more sensitive to heat than Salmonella.-Weibull model was a good fit to describe thermal death kinetics of EHEC and Salmonella.-Flour storage at 35°C may be a feasible method for microbial reduction.

Impact of whole genome sequencing on the investigation of food-borne outbreaks of Shiga toxin-producing Escherichia coli serogroup O157:H7, England, 2013 to 2017.

We aim to provide insight and guidance on the utility of whole genome sequencing (WGS) data for investigating food-borne outbreaks of Shiga toxin-producing Escherichia coli (STEC) O157:H7 in England between 2013 and 2017. Analysis of WGS data delivered an unprecedented level of strain discrimination when compared with multilocus variable number tandem repeat analysis. The robustness of the WGS method ensured confidence in the microbiological identification of linked cases, even when epidemiological links were obscured. There was evidence that phylogeny derived from WGS data can be used to trace the geographical origin of an isolate. Further analysis of the phylogenetic data provided insight on the evolutionary context of emerging pathogenic strains. Publically available WGS data linked to the clinical, epidemiological and environmental context of the sequenced strain has improved trace back investigations during outbreaks. Expanding the use of WGS-based typing analysis globally will ensure the rapid implementation of interventions to protect public health, inform risk assessment and facilitate the management of national and international food-borne outbreaks of STEC O157:H7.

Evaluation of bacteriophage efficacy in reducing the impact of single and mixed infections with Escherichia coli and infectious bronchitis in chickens

ABSTRACTInfectious bronchitis virus (IBV) represents a major threat to poultry production worldwide particularly when complicated with bacterial infection. In the present study samples were collected from forty broiler farms with respiratory manifestations to characterize IBV and E. coli. Bacteriophages were isolated and enriched from sampled farms to study its efficacy to control single and mixed infections with E. coli and IBV in vivo. Twelve out of forty farms were positive for IBV. Phylogenetic analysis of partial spike protein revealed that all positive cases clustered within the GI-23 genotype. Eight out of forty farms were positive for E. coli serogroups O26, O78, O86, O114, O119, with O125 found on three farms. Bacteriophage treatment delayed the onset and reduced the severity of clinical signs, and prevented the mortality associated with single and mixed infection with IBV and E. coli. Furthermore, in mixed infections, bacteriophage treatment significantly reduced E. coli as well as IBV shedding. Groups treated with bacteriophages showed a significant reduction of E. coli shedding that gradually decreased over time, in contrast to higher and gradually increasing shedding without bacteriophage treatment. In conclusion, bacteriophage treatment significantly reduced the pathogenicity and shedding of IBVand E. coli in mixed infections.

Presence of Shiga Toxin-Producing Escherichia coli (STEC) in Fresh Beef Marketed in 13 Regions of ITALY (2017).

The aim of this study was to determine the prevalence of Shiga toxin-producing Escherichia coli in fresh beef marketed in 2017 in 13 regions of Italy, to evaluate the potential risk to human health. According to the ISO/TS 13136:2012 standard, 239 samples were analysed and nine were STEC positive, from which 20 strains were isolated. The STEC-positive samples were obtained from Calabria (n = 1), Campania (n = 1), Lazio (n = 2), Liguria (n = 1), Lombardia (n = 1) and Veneto (n = 3). All STEC strains were analysed for serogroups O26, O45, O55, O91, O103, O104, O111, O113, O121, O128, O145, O146 and O157, using Real-Time PCR. Three serogroups were identified amongst the 20 strains: O91 (n = 5), O113 (n = 2), and O157 (n = 1); the O-group for each of the 12 remaining STEC strains was not identified. Six stx subtypes were detected: stx1a, stx1c, stx2a, stx2b, stx2c and stx2d. Subtype stx2c was the most common, followed by stx2d and stx2b. Subtype stx2a was identified in only one eae-negative strain and occurred in combination with stx1a, stx1c and stx2b. The presence in meat of STEC strains being potentially harmful to human health shows the importance, during harvest, of implementing additional measures to reduce contamination risk.

Hemolytic-uremic syndrome after Escherichia coli urinary tract infection in humans: systematic review of the literature.

Intestinal infections caused by a shigatoxin-positive Escherichia coli (mostly of the serogroups O26, O45, O103, O111, O121, O145 and especially O157) are a common cause of hemolytic-uremic syndrome. Hemolytic-uremic syndrome was first linked with an E. coli urinary tract infection 40years ago. We conducted a systematic review of the literature addressing the association between E. coli urinary tract infection and hemolytic-uremic syndrome. For the final analysis, we retained 23 original reports published since 1979. Five unselected pediatric case series addressed the possible occurrence of hemolytic-uremic syndrome after an acute symptomatic E. coli urinary tract infection among 266 cases and found the mentioned association in 8 (3.0%) cases. We also found 28 individual cases (17 females and 11 males) of hemolytic-uremic syndrome preceded by an E. coli urinary tract infection: 16 children aged from 2days to 6.0years and 12 adults aged from 22 to 75years. Testing for shigatoxin, performed in 19 cases, was positive in 15 cases. E. coli serotyping was performed in 18 cases: testing for serotype O157, O103 and O145 was positive in one, one and two cases, respectively, while testing for serotype O26, O45, O111 and O121 was always negative. Hemolytic-uremic syndrome rarely occurs after an acute E. coli urinary tract infection. It affects both children and adults and is mostly caused by germs that are shigatoxin-positive.