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Dalmacio Vélez Sársfield, Argentina

Miko A.,Federal Institute for Risk Assessment BfR Berlin | Rivas M.,Servicio Fisiopatogenia | Bentancor A.,University of Buenos Aires | Delannoy S.,French Agency for Food | And 2 more authors.
Frontiers in cellular and infection microbiology | Year: 2014

More than 400 serotypes of Shiga toxin-producing Escherichia coli (STEC) have been implicated in outbreaks and sporadic human diseases. In recent years STEC strains belonging to serogroup O178 have been commonly isolated from cattle and food of bovine origin in South America and Europe. In order to explore the significance of these STEC strains as potential human pathogens, 74 German and Argentinean E. coli O178 strains from animals, food and humans were characterized phenotypically and investigated for their serotypes, stx-genotypes and 43 virulence-associated markers by a real-time PCR-microarray. The majority (n = 66) of the O178 strains belonged to serotype O178:H19. The remaining strains divided into O178:H7 (n = 6), O178:H10 (n = 1), and O178:H16 (n = 1). STEC O178:H19 strains were mainly isolated from cattle and food of bovine origin, but one strain was from a patient with hemolytic uremic syndrome (HUS). Genotyping of the STEC O178:H19 strains by pulsed-field gel electrophoresis revealed two major clusters of genetically highly related strains which differ in their stx-genotypes and non-Stx putative virulence traits, including adhesins, toxins, and serine-proteases. Cluster A-strains including the HUS-strain (n = 35) carried genes associated with severe disease in humans (stx2a, stx2d, ehxA, saa, subAB1, lpfAO113 , terE combined with stx1a, espP, iha). Cluster B-strains (n = 26) showed a limited repertoire of virulence genes (stx2c, pagC, lpfAO113 , espP, iha). Among O178:H7 strains isolated from deer meat and patients with uncomplicated disease a new STEC variant was detected that is associated with the genotype stx1c/stx2b/ehxA/subAB2/espI/[terE]/espP/iha. None of the STEC O178 strains was positive for locus of enterocyte effacement (LEE)- and nle-genes. Results indicate that STEC O178:H19 strains belong to the growing group of LEE-negative STEC that should be considered with respect to their potential to cause diseases in humans.

Feng P.C.H.,College Park | Keys C.,College Park | Lacher D.,FDA | Monday S.R.,College Park | And 4 more authors.
FEMS Microbiology Letters | Year: 2010

We examined O157:non-H7 strains isolated from various sources and geographical locations and found 15/57 strains to carry eae alleles, including α, β, ε and κ/δ, suggesting that these strains may be prevalent. All strains were serologically and genetically confirmed to be O157, but none were the H7 serotype or carried any trait virulence factors of the Escherichia coli O157:H7 serotype. Genetic H typing of the eae-positive strains showed that the α-eae-bearing strain was H45, while the β- and ε-eae strains were H16 and the κ/δ-eae strains were H39. The β- and ε-eae-bearing O157:H16 strains shared ∼90% pulsed-field gel electrophoresis (PFGE) similarity and were distinct from the other strains that had other eae alleles. Interestingly, an ε-eae O157:H16 strain isolated from meat in France shared PFGE similarity to the O157:H16 strains from water in the United States. Multilocus sequence typing showed that there is clonal diversity within the O157 serogroup, as some O157:non-H7 strains clustered with EPEC clonal groups, while others clustered within the ST-171 group of diverse strains and serotypes that had not previously included any strains from the O157 serogroup. Clonal analysis also showed that none of the eae-positive O157:non-H7 strains we examined were closely related to the pathogenic O157:H7 serotype. © Journal compilation © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd.

Lucero Estrada C.S.M.,National University of San Luis | Alcaraz L.E.,National University of San Luis | Satorres S.E.,National University of San Luis | Manfredi E.,Servicio Fisiopatogenia | Velazquez L.C.,National University of San Luis
Brazilian Journal of Microbiology | Year: 2013

An increase in the consumption of fruit juices and minimally processed fruits salads has been observed in recent years all over the world. In this work, the microbiological quality of artisan fruit salads was analysed. Faecal coliforms, Salmonella spp, Shigella spp, Yersinia enterocolitica and Escherichia coli O157:H7 were not detected; nevertheless, eleven strains of Staphylococcus aureus were isolated. By multiplex PCR, all isolates showed positive results for S. aureus 16S rRNA gene and 63.6% of them were positive for sea gene. Furthermore, PCR sea positive strains were able to produce the corresponding enterotoxin. Finally, the inactivation of these strains in fruit salads by nisin, lysozyme and EDTA, was studied. EDTA produced a total S. aureus growth inhibition after 60 h of incubation at a concentration of 250 mg/L. The presence of S. aureus might indicate inadequate hygiene conditions during salad elaboration; however, the enterotoxigenicity of the strains isolated in this study, highlights the risk of consumers' intoxication. EDTA could be used to inhibit the growth of S. aureus in artisan fruit salads and extend the shelf life of these products. © 2013, Sociedade Brasileira de Microbiologia.

Gadea M.D.P.,University of the Republic of Uruguay | Deza N.,Servicio Fisiopatogenia | Mota M.I.,University of the Republic of Uruguay | Carbonari C.,Servicio Fisiopatogenia | And 9 more authors.
Revista Argentina de Microbiologia | Year: 2012

STEC strains can infect extra-intestinal sites such as the human urinary tract and sometimes cause severe complications. We report two cases of urinary tract infection caused by STEC in two elderly women with comorbidities. Although both strains belonged to the O157:H7 serotype and carried genes associated with severe illness, none of the patients developed hemolytic uremic syndrome (HUS). These findings provide additional evidence for the presence of these agents in our country and in the region, and highlight the need to maintain an active surveillance system of HUS cases, placing special emphasis on the study of other sites of infection in patients with non- diarrheal HUS.

Jure M.A.,National University of Tucuman | Condori M.S.,San Miguel de Tucuman | Condori M.S.,National University of Tucuman | Terrazzino G.P.,National University of Tucuman | And 6 more authors.
Revista Argentina de Microbiologia | Year: 2015

Escherichia coli O157 is an emergent pathogen associated with diarrhea, hemorrha-gic colitis and hemolytic uremic syndrome. Meat products constitute an important transmissionsource of this microorganism. The aims of this study were to characterize E. coli O157 isolatedfrom cattle and meat products collected from abattoirs and retail stores, to establish the clonalrelatedness among regional isolates and to compare them with those in the national database.Between 2004 and 2013, 169 minced meat, 35 sausage and 216 carcass samples were analy-zed. Thirteen E. coli O157 isolates were identified; 6 of which were O157:H7 and characterizedas stx2c(vh-a)/eae/ehxA (n = 5) and stx2/eae/ehxA (n = 1). The 7 remaining isolates were non-toxigenic E. coli strains, and serotyped as O157:NT (n = 4), O157:NM (n = 1), O157:ND (n = 1)and O157:H16 (n = 1). The strains yielded different XbaI-PFGE patterns. Compared to the E. coliO157 isolates in the National Database, none of these patterns have been previously detectedin strains of different origin in Argentina. © 2015 Asociación Argentina de Microbiología.

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