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Alberto E. Parma - One of the best experts on this subject based on the ideXlab platform.
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Verotoxins in Bovine and Meat Verotoxin-Producing Escherichia coli Isolates: Type, Number of Variants, and Relationship to Cytotoxicity
Applied and Environmental Microbiology, 2010Co-Authors: Alejandra Krüger, Paula M. A. Lucchesi, Alberto E. ParmaAbstract:In this study, we determined vt subtypes and evaluated verotoxicity in basal as well as induced conditions of verotoxin-producing Escherichia coli (VTEC) strains isolated from cattle and meat products. Most (87%) of the 186 isolates carried a vt2 gene. Moreover, the vt2 subtype, which is associated with serious disease, was present in 42% of our VTEC collection. The other vt subtypes detected were vt1, vt1d, vt2vha, vt2vhb, vt2O118, vt2d (mucus activatable), and vt2g. A total of 41 (22%) of the isolates possessed more than one vt subtype in its genome, and among them the most frequent combination was vt1/vt2, but we also observed multiple combinations among vt2 subtypes. Differences in verotoxicity titers were found among a selection of 54 isolates. Among isolates with a single vt2 variant, those carrying the vt2 subtype had high titers under both uninduced and induced conditions. However, the highest increase in cytotoxicity under mitomycin C treatment was detected among the strains carrying vt2vha or vt2hb variants. Notably, the isolates carrying the vt1 subtype showed a lesser increase than that of most of the vt2-positive VTEC strains. Furthermore, the presence of more than one vt gene variant in the same isolate was not reflected in higher titers, and generally the titers were lower than those for strains with only one gene variant. The main observation was that both basal and induced cytotoxic effects seemed to be associated with the type and number of vt variants more than with the serotype or origin of the isolate.
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First isolation of the enterohaemorrhagic Escherichia coli O145:H- from cattle in feedlot in Argentina
BMC Microbiology, 2002Co-Authors: Nora L Padola, Marcelo E. Sanz, Miguel Blanco, Jesús E. Blanco, Jorge Blanco, Paula M. A. Lucchesi, Analía I Etcheverría, Guillermo H Arroyo, Alberto E. ParmaAbstract:Background Enterohaemorrhagic Escherichia coli (EHEC) is considered to be common cause of haemorrhagic colitis (HC), thrombotic thrombocytopenic purpura and haemolytic uraemic syndrome (HUS) in humans. In a previous paper, we have demonstrated that EHEC are commonly found in the intestines of livestock. Infections in humans are, in part, a consequence of consumption of undercooked meat or raw milk. Argentina has one of the highest records of HUS (300–400 cases/year; 22/100,000 children under 4 years of age). The aim of this work is to communicate the first isolation of O145:H-from cattle in this country and characterize the virulence cassette, providing useful information to evaluate the risk of foodborne transmission of this emergent non-O157:H7 serotype. Results EHEC O145:H- was isolated from cattle in an Argentinian feedlot. Pheno- and genotype of nine strains were characterized, corresponding to several virulence cassettes: VT2^+ eaeA ^+ Mp^+ (n = 5), VT2^+ eaeA ^+ (n = 1), VT1^+ eaeA ^+ Mp^+ (n = 2), and VT1^+ eaeA ^+ (n = 1). Strains isolated from the same animal were considered only when they showed a different virulence pattern. The clonal relationship was studied by RAPD. Strains were distributed in two RAPD profiles, which corresponded to the presence of either, VT1^+ or VT2^+ genotype. No difference was detected by RAPD analysis between Mp^+ or Mp^- strains. Conclusions This was the first isolation of EHEC O145:H- serotype in Argentina enlarging the list of non-O157:H7 serotypes isolated from cattle in this country by us. All O145:H-strains carried several virulence factors which allow us to predict their potential ability to develop haemolytic uraemic syndrome in humans.
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Prevalence of bovine verotoxin-producing Escherichia coli in Argentina.
European Journal of Epidemiology, 1998Co-Authors: Marcelo E. Sanz, M.r. Viñas, Alberto E. ParmaAbstract:Faecal swabs obtained from 126 calves and 118 cows in Argentina were investigated for the presence of verotoxin-producing Escherichia coli (VTEC). VTEC strains were recovered from 10 (23%) of 43 calves with diarrhoea, from 24 (29%) of 83 healthy calves, from 40 (44%) of 91 healthy cows waiting at the slaughterhouse, and from 6 (22%) of 27 healthy grazing cattle. PCR showed that 21 (9%) of animals carried VT1+ strains, 49 (20%) VT2+ strains and 10 (4%) VT1+ VT2+ strains. VT1+ strains predominated among calves (16% versus 0.8%; p < 0.001). The presence of eae gene was significantly more frequent among VTEC strains isolated from calves (78%; 46/59) than from cows (2%; 1/65) (p < 0.001). Furthermore, eae gene was more prevalent in VT1+ strains (97%; 32/33) than in VT2+ strains (14%; 10/70) (p < 0.001) and in VT1+ VT2+ strains (24%; 5/21) (p < 0.001). Sorbitol negative high virulent strains serogroups O157 were not detected. This study indicates that cattle are a reservoir of VTEC strains, and that eae gene is associated with VT1+ strains that are predominating among young animals. Fortunately, only adult animals are taken to the slaughterhouse, among which VTEC strains negative for eae gen are predominating.
Miguel Blanco - One of the best experts on this subject based on the ideXlab platform.
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First isolation of the enterohaemorrhagic Escherichia coli O145:H- from cattle in feedlot in Argentina
BMC Microbiology, 2002Co-Authors: Nora L Padola, Marcelo E. Sanz, Miguel Blanco, Jesús E. Blanco, Jorge Blanco, Paula M. A. Lucchesi, Analía I Etcheverría, Guillermo H Arroyo, Alberto E. ParmaAbstract:Background Enterohaemorrhagic Escherichia coli (EHEC) is considered to be common cause of haemorrhagic colitis (HC), thrombotic thrombocytopenic purpura and haemolytic uraemic syndrome (HUS) in humans. In a previous paper, we have demonstrated that EHEC are commonly found in the intestines of livestock. Infections in humans are, in part, a consequence of consumption of undercooked meat or raw milk. Argentina has one of the highest records of HUS (300–400 cases/year; 22/100,000 children under 4 years of age). The aim of this work is to communicate the first isolation of O145:H-from cattle in this country and characterize the virulence cassette, providing useful information to evaluate the risk of foodborne transmission of this emergent non-O157:H7 serotype. Results EHEC O145:H- was isolated from cattle in an Argentinian feedlot. Pheno- and genotype of nine strains were characterized, corresponding to several virulence cassettes: VT2^+ eaeA ^+ Mp^+ (n = 5), VT2^+ eaeA ^+ (n = 1), VT1^+ eaeA ^+ Mp^+ (n = 2), and VT1^+ eaeA ^+ (n = 1). Strains isolated from the same animal were considered only when they showed a different virulence pattern. The clonal relationship was studied by RAPD. Strains were distributed in two RAPD profiles, which corresponded to the presence of either, VT1^+ or VT2^+ genotype. No difference was detected by RAPD analysis between Mp^+ or Mp^- strains. Conclusions This was the first isolation of EHEC O145:H- serotype in Argentina enlarging the list of non-O157:H7 serotypes isolated from cattle in this country by us. All O145:H-strains carried several virulence factors which allow us to predict their potential ability to develop haemolytic uraemic syndrome in humans.
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Distribution and characterization of faecal verotoxin-producing Escherichia coli (VTEC) isolated from healthy cattle.
Veterinary Microbiology, 1997Co-Authors: Miguel Blanco, Jesús E. Blanco, Jorge Blanco, Azucena Mora, Cristina Prado, María Pilar Alonso, M. Mouriño, Cristina Madrid, Carlos Balsalobre, Antonio JuárezAbstract:Abstract Faecal swabs obtained from a random sample of 268 cows and 90 calves on 19 Lugo farms were examined for verotoxin-producing Escherichia coli (VTEC). We found VTEC on 95% of the farms. The prevalence rates of VTEC infection in asymptomatic cows and calves were estimated to be 35 and 37%, respectively. The proportion of animals infected on each farm ranged from 0 to 100%. VTEC strains isolated from healthy cattle belonged to 27 O serogroups; however, 57% (85 of 149) were of one of 8 serogroups (O2, O8, O22, O77, O82, O105, O113 and O171). Nearly 60% of the bovine VTEC strains belonged to serogroups that cause haemorrhagic colitis and haemolytic uraemic syndrome in humans. The VTEC were all non-O157:H7; 91% were eae -negative and 86% produced VT2 or VT1 and VT2. These characteristics are different from those of VTEC isolated from calves with diarrhoea.
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Genes coding for Shiga-like toxins in bovine verotoxin-producing Escherichia coli (VTEC) strains belonging to different O:K:H serotypes
Veterinary Microbiology, 1994Co-Authors: Miguel Blanco, Jesús E. Blanco, Jorge Blanco, Enrique A. González, Tânia A. T. Gomes, L.fernando Zerbini, Tomomasa Yano, A. F. Pestana De CastroAbstract:Abstract Forty-six verotoxin-producing Escherichia coli (VTEC) strains isolated from diarrhoeic and healthy calves in Spain were examined for DNA sequences homologous to genes for verotoxins (VT1 and VT2) and enterotoxins (LT-I, LT-II, STaH, STaP and STb). Hybridisation showed that 26 (57%) of VTEC strains carried VT1 genes, 13 (28%) possessed VT2 genes, and 7 (15%) carried both VT1 and VT2 genes. No VTEC strains hybridised with DNA probes for enterotoxins. A correlation was found between the serotype and type of VT produced. Thus, all strains of serotypes O26:K-:H11 (13 strains), O103:K-:H2 (3 strains) and O128:K?:H- (4 strains) hybridised with the VT1 probe only, whereas all strains of serotypes O4:K-:H4 (3 strains) and O113:K-:H21 (4 strains) were positive with the VT2 probe only. By contrast, O81:K?:H28 (2 strains) and O157:K-:H- (2 strains) strains hybridised with both VT1 and VT2 probes. One strain of serotype O157:K-:H7 was VT2 positive.
Roman Putanowicz - One of the best experts on this subject based on the ideXlab platform.
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visualization of large data sets by mixing tcl and c interfaces to the VTK library
Computers & Structures, 2007Co-Authors: Frederic Magoules, Roman PutanowiczAbstract:This article describes a technique to build applications for the visualization of large data sets using VTK library and components written in Tcl and C++. VTK is a software system for computer graphics, visualization and image processing. VTK library is written in C++ however it provides interfaces to the scripting languages Tcl, Python and Java. Though it is possible to write a whole VTK application in a scripting language like Tcl, it is more suitable, for efficiency reasons, to implement some functionality in a compiled language like C/C++ for instance. This article presents in through details how to access VTK objects from different languages and how to mix Tcl and C++ components in one application.
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Visualization of large data sets by mixing Tcl and C++ interfaces to the VTK library
Computers & Structures, 2007Co-Authors: Frederic Magoules, Roman PutanowiczAbstract:This article describes a technique to build applications for the visualization of large data sets using VTK library and components written in Tcl and C++. VTK is a software system for computer graphics, visualization and image processing. VTK library is written in C++ however it provides interfaces to the scripting languages Tcl, Python and Java. Though it is possible to write a whole VTK application in a scripting language like Tcl, it is more suitable, for efficiency reasons, to implement some functionality in a compiled language like C/C++ for instance. This article presents in through details how to access VTK objects from different languages and how to mix Tcl and C++ components in one application.
Jorge Blanco - One of the best experts on this subject based on the ideXlab platform.
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First isolation of the enterohaemorrhagic Escherichia coli O145:H- from cattle in feedlot in Argentina
BMC Microbiology, 2002Co-Authors: Nora L Padola, Marcelo E. Sanz, Miguel Blanco, Jesús E. Blanco, Jorge Blanco, Paula M. A. Lucchesi, Analía I Etcheverría, Guillermo H Arroyo, Alberto E. ParmaAbstract:Background Enterohaemorrhagic Escherichia coli (EHEC) is considered to be common cause of haemorrhagic colitis (HC), thrombotic thrombocytopenic purpura and haemolytic uraemic syndrome (HUS) in humans. In a previous paper, we have demonstrated that EHEC are commonly found in the intestines of livestock. Infections in humans are, in part, a consequence of consumption of undercooked meat or raw milk. Argentina has one of the highest records of HUS (300–400 cases/year; 22/100,000 children under 4 years of age). The aim of this work is to communicate the first isolation of O145:H-from cattle in this country and characterize the virulence cassette, providing useful information to evaluate the risk of foodborne transmission of this emergent non-O157:H7 serotype. Results EHEC O145:H- was isolated from cattle in an Argentinian feedlot. Pheno- and genotype of nine strains were characterized, corresponding to several virulence cassettes: VT2^+ eaeA ^+ Mp^+ (n = 5), VT2^+ eaeA ^+ (n = 1), VT1^+ eaeA ^+ Mp^+ (n = 2), and VT1^+ eaeA ^+ (n = 1). Strains isolated from the same animal were considered only when they showed a different virulence pattern. The clonal relationship was studied by RAPD. Strains were distributed in two RAPD profiles, which corresponded to the presence of either, VT1^+ or VT2^+ genotype. No difference was detected by RAPD analysis between Mp^+ or Mp^- strains. Conclusions This was the first isolation of EHEC O145:H- serotype in Argentina enlarging the list of non-O157:H7 serotypes isolated from cattle in this country by us. All O145:H-strains carried several virulence factors which allow us to predict their potential ability to develop haemolytic uraemic syndrome in humans.
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Distribution and characterization of faecal verotoxin-producing Escherichia coli (VTEC) isolated from healthy cattle.
Veterinary Microbiology, 1997Co-Authors: Miguel Blanco, Jesús E. Blanco, Jorge Blanco, Azucena Mora, Cristina Prado, María Pilar Alonso, M. Mouriño, Cristina Madrid, Carlos Balsalobre, Antonio JuárezAbstract:Abstract Faecal swabs obtained from a random sample of 268 cows and 90 calves on 19 Lugo farms were examined for verotoxin-producing Escherichia coli (VTEC). We found VTEC on 95% of the farms. The prevalence rates of VTEC infection in asymptomatic cows and calves were estimated to be 35 and 37%, respectively. The proportion of animals infected on each farm ranged from 0 to 100%. VTEC strains isolated from healthy cattle belonged to 27 O serogroups; however, 57% (85 of 149) were of one of 8 serogroups (O2, O8, O22, O77, O82, O105, O113 and O171). Nearly 60% of the bovine VTEC strains belonged to serogroups that cause haemorrhagic colitis and haemolytic uraemic syndrome in humans. The VTEC were all non-O157:H7; 91% were eae -negative and 86% produced VT2 or VT1 and VT2. These characteristics are different from those of VTEC isolated from calves with diarrhoea.
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Genes coding for Shiga-like toxins in bovine verotoxin-producing Escherichia coli (VTEC) strains belonging to different O:K:H serotypes
Veterinary Microbiology, 1994Co-Authors: Miguel Blanco, Jesús E. Blanco, Jorge Blanco, Enrique A. González, Tânia A. T. Gomes, L.fernando Zerbini, Tomomasa Yano, A. F. Pestana De CastroAbstract:Abstract Forty-six verotoxin-producing Escherichia coli (VTEC) strains isolated from diarrhoeic and healthy calves in Spain were examined for DNA sequences homologous to genes for verotoxins (VT1 and VT2) and enterotoxins (LT-I, LT-II, STaH, STaP and STb). Hybridisation showed that 26 (57%) of VTEC strains carried VT1 genes, 13 (28%) possessed VT2 genes, and 7 (15%) carried both VT1 and VT2 genes. No VTEC strains hybridised with DNA probes for enterotoxins. A correlation was found between the serotype and type of VT produced. Thus, all strains of serotypes O26:K-:H11 (13 strains), O103:K-:H2 (3 strains) and O128:K?:H- (4 strains) hybridised with the VT1 probe only, whereas all strains of serotypes O4:K-:H4 (3 strains) and O113:K-:H21 (4 strains) were positive with the VT2 probe only. By contrast, O81:K?:H28 (2 strains) and O157:K-:H- (2 strains) strains hybridised with both VT1 and VT2 probes. One strain of serotype O157:K-:H7 was VT2 positive.
Jesús E. Blanco - One of the best experts on this subject based on the ideXlab platform.
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First isolation of the enterohaemorrhagic Escherichia coli O145:H- from cattle in feedlot in Argentina
BMC Microbiology, 2002Co-Authors: Nora L Padola, Marcelo E. Sanz, Miguel Blanco, Jesús E. Blanco, Jorge Blanco, Paula M. A. Lucchesi, Analía I Etcheverría, Guillermo H Arroyo, Alberto E. ParmaAbstract:Background Enterohaemorrhagic Escherichia coli (EHEC) is considered to be common cause of haemorrhagic colitis (HC), thrombotic thrombocytopenic purpura and haemolytic uraemic syndrome (HUS) in humans. In a previous paper, we have demonstrated that EHEC are commonly found in the intestines of livestock. Infections in humans are, in part, a consequence of consumption of undercooked meat or raw milk. Argentina has one of the highest records of HUS (300–400 cases/year; 22/100,000 children under 4 years of age). The aim of this work is to communicate the first isolation of O145:H-from cattle in this country and characterize the virulence cassette, providing useful information to evaluate the risk of foodborne transmission of this emergent non-O157:H7 serotype. Results EHEC O145:H- was isolated from cattle in an Argentinian feedlot. Pheno- and genotype of nine strains were characterized, corresponding to several virulence cassettes: VT2^+ eaeA ^+ Mp^+ (n = 5), VT2^+ eaeA ^+ (n = 1), VT1^+ eaeA ^+ Mp^+ (n = 2), and VT1^+ eaeA ^+ (n = 1). Strains isolated from the same animal were considered only when they showed a different virulence pattern. The clonal relationship was studied by RAPD. Strains were distributed in two RAPD profiles, which corresponded to the presence of either, VT1^+ or VT2^+ genotype. No difference was detected by RAPD analysis between Mp^+ or Mp^- strains. Conclusions This was the first isolation of EHEC O145:H- serotype in Argentina enlarging the list of non-O157:H7 serotypes isolated from cattle in this country by us. All O145:H-strains carried several virulence factors which allow us to predict their potential ability to develop haemolytic uraemic syndrome in humans.
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Distribution and characterization of faecal verotoxin-producing Escherichia coli (VTEC) isolated from healthy cattle.
Veterinary Microbiology, 1997Co-Authors: Miguel Blanco, Jesús E. Blanco, Jorge Blanco, Azucena Mora, Cristina Prado, María Pilar Alonso, M. Mouriño, Cristina Madrid, Carlos Balsalobre, Antonio JuárezAbstract:Abstract Faecal swabs obtained from a random sample of 268 cows and 90 calves on 19 Lugo farms were examined for verotoxin-producing Escherichia coli (VTEC). We found VTEC on 95% of the farms. The prevalence rates of VTEC infection in asymptomatic cows and calves were estimated to be 35 and 37%, respectively. The proportion of animals infected on each farm ranged from 0 to 100%. VTEC strains isolated from healthy cattle belonged to 27 O serogroups; however, 57% (85 of 149) were of one of 8 serogroups (O2, O8, O22, O77, O82, O105, O113 and O171). Nearly 60% of the bovine VTEC strains belonged to serogroups that cause haemorrhagic colitis and haemolytic uraemic syndrome in humans. The VTEC were all non-O157:H7; 91% were eae -negative and 86% produced VT2 or VT1 and VT2. These characteristics are different from those of VTEC isolated from calves with diarrhoea.
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Genes coding for Shiga-like toxins in bovine verotoxin-producing Escherichia coli (VTEC) strains belonging to different O:K:H serotypes
Veterinary Microbiology, 1994Co-Authors: Miguel Blanco, Jesús E. Blanco, Jorge Blanco, Enrique A. González, Tânia A. T. Gomes, L.fernando Zerbini, Tomomasa Yano, A. F. Pestana De CastroAbstract:Abstract Forty-six verotoxin-producing Escherichia coli (VTEC) strains isolated from diarrhoeic and healthy calves in Spain were examined for DNA sequences homologous to genes for verotoxins (VT1 and VT2) and enterotoxins (LT-I, LT-II, STaH, STaP and STb). Hybridisation showed that 26 (57%) of VTEC strains carried VT1 genes, 13 (28%) possessed VT2 genes, and 7 (15%) carried both VT1 and VT2 genes. No VTEC strains hybridised with DNA probes for enterotoxins. A correlation was found between the serotype and type of VT produced. Thus, all strains of serotypes O26:K-:H11 (13 strains), O103:K-:H2 (3 strains) and O128:K?:H- (4 strains) hybridised with the VT1 probe only, whereas all strains of serotypes O4:K-:H4 (3 strains) and O113:K-:H21 (4 strains) were positive with the VT2 probe only. By contrast, O81:K?:H28 (2 strains) and O157:K-:H- (2 strains) strains hybridised with both VT1 and VT2 probes. One strain of serotype O157:K-:H7 was VT2 positive.
