Investigación de Escherichia Coli productor de toxinas Shiga (STEC) en carnes y derivados cárnicos / Researching Escherichia Coli as a Shiga (STEC) toxin producer in meat and meat products

Introducción: El término Escherichia coli productor de toxina Shiga (STEC) abarca un grupo de patógenos alimentarios emergentes, implicados en numerosos brotes a nivel mundial. Son responsables de infecciones y enfermedades gastrointestinales graves tales como el síndrome urémico hemolítico (SUH) y la colitis hemorrágica (CH). Muchos alimentos han sido vinculados a estos brotes, destacando las carnes y derivados cárnicos crudos o insuficientemente cocinados. Objetivo: Evaluar la prevalencia de STEC en carnes y derivados, de especies de abasto y cinegéticas, consumidas dentro de las Fuerzas Armadas (FAS). Material y Métodos: Se analiza-ron un total de 170 muestras recibidas en el Servicio de Bromatología y Seguridad Alimentaria, del Centro Militar de Veterinaria. Para determinar la presencia de STEC se empleó la técnica de PCR a tiempo real mediante el uso del kit comercial Custom TaqMan ISO STEC Screening Assay (Thermo Scientific (TM)), siguiendo las instrucciones del fabricante. Para el análisis estadístico se utilizó el programa SPSS. Resultados: La prevalencia de STEC en el total de las muestras analizadas fue de un 19,41 %. La hallada entre los preparados cárnicos de especies de abasto fue de un 25,42 %, mientras que la de derivados de carne de caza, fue de un 27,4 %. Los resultados obtenidos del cribado de STEC mostraron significación estadística. Conclusiones: Los resultados obtenidos concuerdan con la mayoría de estudios anteriormente publicados, recalcando la importancia que representa el control de este grupo de patógenos, pudiéndose ampliar el espectro de matrices a analizar, dada la potencial exposición de los consumidores de las FAS a estos agentes (AU)

Introduction: Shiga toxin-producing Escherichia coli (STEC) is made up of a group of emerging food pathogens, impli-cated in numerous outbreaks worldwide. They are responsible for infections and serious gastrointestinal diseases such as hemolytic uremic syndrome (HUS) and hemorrhagic colitis (HC). Many foods have been linked to these outbreaks, with emphasis on raw or undercooked meat and meat products. Aim: To evaluate the prevalence of STEC in meat and meat products from food-producing and game species, consumed within the Armed Forces (AF). Material and Methods: We analyzed a total of 170 samples received in the Service of Bromatology and Food Safety, of the Veterinary Military Center. To determine the presence of STEC, real-time PCR technique was performed using the "Custom TaqMan ISO STEC Screening Assay" kit (Thermo Scientific(TM), following the manufacturer’s instructions. Statistical analysis was carried out using the SPSS.program. Results: The prevalence of STEC in the to-tal amount of samples analyzed was 19.41%. Prevalence of meat products from food-producing species was 25.42%, whereas the one from game meat was 27.4%. The results obtained from the STEC screening showed statistical significance. Conclusions: The results obtained agree with most of previously published studies, emphasizing the importance of surveillance. Expanding the spectrum of matrices to analyze could be an interest approach, given the potential exposure of AF consumers to these agents (AU)

Plasmaféresis en el tratamiento del síndrome hemolítico-urémico típico / Plasmapheresis in the treatment of typical haemolytic-uraemic syndrome

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Las cepas enterohemorrágicas de «Escherichia coli» como paradigma de patógenos emergentes. Lecciones de la gran epidemia de infección alimentaria centrada en Alemania en mayo y junio de 2011 / Enterohaemorrhagic strains of Escherichia coli as a paradigm of emerging pathogens. Lessons from the large outbreak of foodborne infections centred in Germany throughout May and June of 2011

Las cepas enterohemorrágicas de Escherichia coli (EHEC) son patógenos zoonóticos de transmisión alimentaria asociados a epidemias y a casos esporádicos de diarrea y colitis hemorrágica, cuadros que pueden complicarse y dar lugar al síndrome hemolítico urémico (HUS). La importancia de las cepas EHEC se debe a la gravedad del HUS, que es la causa más frecuente de insuficiencia renal aguda en los niños en América y Europa. E. coli O157:H7 es el serotipo fundamental del patotipo EHEC. Ya hace años se predijo que cepas EHEC de otros serotipos podrían convertirse en importantes patógenos transmitidos por alimentos, y desde entonces estos microorganismos se han relacionado con numerosos casos de enfermedad en todo el mundo. La incidencia de estos serotipos distintos del O157:H7sigue creciendo, lo que significa que pueden considerarse patógenos emergentes. Un ejemplo reciente es el gran brote de infecciones transmitidas por los alimentos y causadas por EHEC O104:H4, que se centró principalmente en Alemania durante mayo y junio de 2011. La cepa responsable del brote posee una combinación de factores de virulencia típicos de diferentes patotipos de E. coli, lo que corrobora que la plasticidad de los genomas bacterianos facilita la emergencia de nuevos patógenos especialmente virulentos. Las investigaciones epidemiológicas identificaron el origen del brote en una partida de semillas de alholva (fenogreco) importadas de Egipto en 2009. La dimensión internacional de esta epidemia ilustra la urgente necesidad de mejorar la vigilancia epidemiológica de las cepas EHEC(AU)

Enterohaemorrhagic strains of Escherichia coli (EHEC) are foodborne zoonotic pathogens associated with major outbreaks and sporadic cases of diarrhoea and haemorrhagic colitisor bloody diarrhea, which can progress to the hemolyticuremic syndrome (HUS). The importance of EHEC lies in the severity of HUS, which is the most frequent cause of acute renal failure in children in the Americas and Europe. It was predicted years ago that EHEC strains other than the prototypic O157:H7 serotype would emerge as significant foodborne pathogens. Since then, these microorganisms have been linked to numerous outbreaks and sporadic cases of disease around the world. The incidence of these serotypes continues to grow, which means they can be considered emerging pathogens. A recent example is the large outbreak of foodborne infections caused by EHEC O104:H4, which was mainly centred in Germany lasting throughout May and June of 2011. The outbreaks train shows a combination of virulence factors from different E. coli pathotypes, highlighting the way in which the plasticity of bacterial genomes facilitates the emergence of new highly virulent pathogens. Epidemiologic investigations traced the origin of the outbreak to fenugreek seeds imported from Egyptin 2009. The international dimension of the outbreak illustrated the urgent need for improving the epidemiologic surveillance of EHEC(AU)

Characteristics of the Shiga-toxin-producing enteroaggregative Escherichia coli O104: H4German outbreak strain and of STEC strains isolated in Spain

A Shiga-toxin-producing Escherichia coli (STEC) strain belonging to serotype O104:H4, phylogenetic group B1 and sequence type ST678, with virulence features common to the enteroaggregative E. coli (EAEC) pathotype, was reported as the cause of the recent 2011 outbreak in Germany. The outbreak strain was determined to carry several virulence factors of extraintestinal pathogenic E. coli (ExPEC) and to be resistant to a wide range of antibiotics. There are only a few reports of serotype O104:H4, which is very rare in humans and has never been detected in animals or food. Several research groups obtained the complete genome sequence of isolates of the German outbreak strain as well as the genome sequences of EAEC of serotype O104:H4 strains from Africa. Those findings suggested that horizontal genetic transfer allowed the emergence of the highly virulent Shiga-toxin-producing enteroaggregative E. coli (STEAEC) O104:H4 strain responsible for the outbreak in Germany. Epidemiologic investigations supported a linkage between the outbreaks in Germany and France and traced their origin to fenugreek seeds imported from Africa. However, there has been no isolation of the causative strain O104:H4 from any of the samples of fenugreek seeds analyzed. Following the German outbreak, we conducted a large sampling to analyze the presence of STEC, EAEC, and other types of diarrheagenic E. coli strains in Spanish vegetables. During June and July 2011, 200 vegetable samples from different origins were analyzed. All were negative for the virulent serotype O104:H4 and only one lettuce sample (0.6%) was positive for a STEC strain of serotype O146:H21 (stx1, stx2), considered of low virulence. Despite the single positive case, the hygienic and sanitary quality of Spanish vegetables proved to be quite good. In 195 of the 200 samples (98%), <10 colony-forming units (cfu) of E. coli per gram were detected, and the microbiological levels of all samples were satisfactory (<100 cfu/g). The samples were also negative for other pathotypes of diarrheagenic E. coli (EAEC, ETEC, tEPEC, and EIEC). Consistent with data from other countries, STEC belonging to serotype O157:H7 and other serotypes have been isolated from beef, milk, cheese, and domestic (cattle, sheep, goats) and wild (deer, boar, fox) animals in Spain. Nevertheless, STEC outbreaks in Spain are rare (AU)

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HeLa-cell adherence patterns and actin aggregationof enteropathogenic Escherichia coli (EPEC)and Shiga-toxin-producing E. coli (STEC) strainscarrying different eae and tir alleles

A collection of 69 eae-positive strains expressing 29 different intimin types and eight tir alleles was characterized with respect to their adherence patterns to HeLa cells, ability to promote actin accumulation in vitro, the presence of bfpA alleles in positive strains, and bundle-forming pilus (BFP) expression. All of the nine typical enteropathogenic Escherichia coli (tEPEC) studied harbored the enteropathogenic E. coli adherence factor (EAF) plasmid, as shown by PCR and/or EAF probe results. In addition, they were positive for bfpA, as shown by PCR, and BFP expression, as confirmed by immunofluorescence (IFL) and/or immunoblotting (IBL) assays. Localized adherence (LA) was exclusively displayed by those nine tEPEC, while localized-adherence-like (LAL) was the most frequent pattern among atypical EPEC (aEPEC) and Shiga-toxinproducing E. coli (STEC). All LA and LAL strains were able to cause attaching and effacing (AE) lesions, as established by means of the FAS test. There was a significant association between the presence of tir allele alpha1 and bfpA-positive strains, and consequently, with the LA pattern. However, intimin type or bfpA was not associated with the adherence pattern displayed in HeLa cells. Among the eight bfpA alleles detected, a new type (beta10; accession number FN391178) was identified in a strain of serotype O157:H45, and a truncated variant (beta3.2-t; accession number FN 391181) in four strains belonging to different pathotypes (AU)

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Virulence genes and intimin types of Shiga-toxin-producing Escherichia coli isolated from cattle and beef products in Argentina / Genes de virulencia y tipos de intiminas de Escherichia coli productoras de toxinas Shiga aisladas de ganado bovino y carne de vacuno en Argentina

A total of 153 Shiga-toxin-producing Escherichia coli (STEC) isolates from feces of cattle and beef products (hamburgers and ground beef) in Argentina were characterized in this study. PCR showed that 22 (14%) isolates carried stx1 genes, 113 (74%) possessed stx2 genes and 18 (12%) both stx1 and stx2. Intimin (eae), enterohemolysin (ehxA), and STEC autoagglutinating adhesin (saa) virulence genes were detected in 36 (24%), 70 (46%) and in 34 (22%) of the isolates, respectively. None of 34 saa-positive isolates carried the gene eae, and 31 were ehxA-positive. Fourteen (7 of serotype O26:H11 and 4 of serotype O5:H-) isolates had intimin b1, 16 isolates possessed intimin g1 (11 of serotype O145:H- and 5 of serotype O157:H7), 5 isolates had intimin type e1 (4 of serotypes O103:H- and O103:H2), and one isolate O111:H- showed intimin type q/g2. Although the 153 STEC isolates belonged to 63 different seropathotypes, only 12 accounted for 58% of isolates. Seropathotype ONT:H- stx2 (18 isolates) was the most common, followed by O171:H2 stx2 (12 isolates), etc. The majority (84%) of STEC isolates belonged to serotypes previously found in human STEC and 56% to serotypes associated with STEC isolated from patients with hemolytic uremic syndrome (HUS). Thus, this study confirms that cattle are a major reservoir of STEC pathogenic for humans. To our knowledge, this is the first study that described the presence of saa gene in STEC of serotypes O20:H19, O39:H49, O74:H28, O79:H19, O116:H21, O120:H19, O141:H7, O141:H8, O174:H21, and ONT:H21. The serotypes O120:H19 and O185:H7 were not previously reported in bovine STEC (AU)

En este estudio hemos caracterizado un total de 153 Escherichia coli productores de toxinas Shiga (STEC) aisladas de las heces de ganado bovino y de carne picada y hamburguesas de vacuno en Argentina. Los ensayos de PCR mostraron que 22 (14%) aislamientos llevaban el gen stx1, 113 (74%) presentaban el gen stx2 y que 18 (12%) tenían ambos genes. Los genes de virulencia para la intimina (eae), la enterohemolisina (ehxA) y la adhesina autoaglutinante de STEC (saa) fueron detectados en 36 (24%), 70 (46%) y 34 (22%) de los aislamientos, respectivamente. Ninguno de los 34 aislamientos saa-positivos llevaba el gen eae, pero 31 eran ehxA-positivos. Catorce aislamientos (7 del serotipo O26:H11 y 4 del serotipo O5:H-) tenían la intimina b1, 16 poseían la intimina g1 (11 del serotipo O145:H- y 5 del serotipo O157:H7), 5 aislamientos eran positivos para la intimina tipo ε1 (4 de los serotipos O103:H- y O103:H2), y un aislamiento O111:H- mostró la intimina tipo θ/g2. Aunque los 153 aislamientos de STEC pertenecían a 63 seropatotipos, sólo 12 constituían el 58% de los aislamientos. El seropatotipo ONT:H- stx2 (18 aislamientos) fue el más común, seguido por el O171:H2 stx2 (12 aislamientos), etc. La mayoría de los aislamientos (84%) de STEC pertenecían a serotipos encontrados previamente en seres humanos y el 56% a serotipos asociados con STEC aislados de pacientes con el síndrome urémico hemolítico (HUS). Por tanto, este estudio confirma que el ganado bovino es un importante reservorio de STEC patógenos para humanos. Según nuestra información, este es el primer estudio que describe la presencia del gen saa en STEC de los serotipos O20:H19, O39:H49, O74:H28, O79:H19, O116:H21, O120:H19, O141:H7, O141:H8, O174:H21, y ONT:H21. Los serotipos O120:H19 y O185:H7 tampoco habían sido descritos previamente en STEC de origen bovino (AU)