Navegando por Palavras-chave "Shiga toxin"

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    Diversity of virulence profiles of Shiga toxin-producing Escherichia coli serotypes in food-producing animals in Brazil
    (Elsevier B.V., 2008-09-30) Oliveira, Murilo Gomes; Feitosa Brito, Jose Renaldi; Tardelli Gomes, Tania Aparecida [UNIFESP]; Cabilio Guth, Beatriz Ernestina [UNIFESP]; Midolli Vieira, Monica Aparecida [UNIFESP]; Furtado Naves, Zita Valeria; Ibelli Vaz, Tania Mara; Irino, Kinue; Inst Adolfo Lutz Registro; Univ Fed Juiz de Fora; Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA); Universidade Federal de São Paulo (UNIFESP)
    The prevalence, serotypes and virulence profiles of Shiga toxin-producing Escherichia coli (STEC) were investigated in 205 healthy beef and dairy cattle. and 106 goats reared in the southeastern region of Minas Gerais State, Brazil. the prevalence of STEC was 57.5% (61/106) in goats, 39.2%, (40/102) in beef cattle and 17.5% (18/103) in dairy cattle. Among the 514 STEC isolates, 40 different serotypes were found and some of them were identified in a specific host. STEC isolates harboring stx(1) corresponded to 15.6% (28/180), 26.7% (16/60) and 24.1% (661274) in beef cattle, dairy cattle and goats. respectively. Stx(2) was found in 30% (54/180), 53.3% (32/60) and 34.7% (95/274) of beef and dairy cattle, and goats. stx(1) Plus Stx(2) sequences were harbored by 54.4% (98/180), 20% (12/60) and 41.2% (113/274) of beef cattle, dairy cattle and goats. respectively. the eae sequence was found in 15% (9/60) and 0.6% (1/180) of STEC isolates from dairy and beef cattle, respectively, and the toxB gene was found only in one O157:H7 strain isolated from beef cattle. Strains with the genetic profiles stx(2) ehxA iha saa and stx(1) stx(2) ehxA iha saa were the most prevalent among STEC isolates from cattle. Profiles stx, Stx(2) ehxA ilia, stx2, and stx, iha accounted for 75.5% (207 /274) of the STEC isolates from goats. While STEC strains carrying either Stx(2) alone or associated with stx(1) were found more frequently in cattle, those harboring sequences stx(1), and Stx(2d) alone or associated with stx(1c) predominated in goats. Our data show a diversity of STEC strains in food-producing animals, most of them carrying genes linked to severe forms of human diseases. (C) 2008 Elsevier B.V. All rights reserved.
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    Estudos sobre o potencial de virulência e filogenia de amostras de Escherichia coli do sorotipo O113:H21
    (Universidade Federal de São Paulo (UNIFESP), 2011-02-22) Santos, Luis Fernando dos [UNIFESP]; Guth, Beatriz Ernestina Cabilio [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    In this study 37 O113:H21 Escherichia coli strains isolated from human infections (03 samples), the animal reservoir (33 samples) and food (1 sample) in different regions of Brazil, were analyzed for their genotypic and phenotypic virulence traits and genetic and phylogenetic backgrounds. The presence of the stx gene, defining the STEC pathotype was observed in all samples of non-human origin. Human samples, lacking this gene, were classified as non-STEC. The search for genes related to the production of toxins, adhesins and autotransporter proteins revealed the occurrence of distinct virulence profiles among samples of different origins. Among the STEC strains the profile composed of ehxA, subAB, epeA, espP, lpfO113, iha and saa, associated or not to cdt-V was the most prevalent. Non-STEC isolates harbored only astA, lpfO113 and iha. The genotype stx2dactivatablewas found in most of the STEC samples. High mass plasmids occurred in 25 of the 37 studied strains, but only in STEC group these plasmids could be confirmed as being the STEC O113 megaplasmid pO113. STEC isolates were also investigated for the occurrence of subtypes of genes and ehxA and regarding the enterohemolysin gene only the subtype A was found; in relation to saa, four distinct subtypes of this gene were present among the studied strains. These subtypes corresponded to variants of 500 to 800 base pairs. Cytotoxicity assays revealed the ability for the expression of subAB and cdt-V genes in 13 and 07 STEC strains respectively. Interaction assays using Caco-2 and T84 cell lines demonstrated that 13 strains had the capacity of invading the cells. Ability to form biofilm in different temperatures was observed in the majority of the studied strains. The search for the presence and expression of curli and type I fimbriae related genes were found to give positive results for the majority of the strains; however this fact had no correlation with biofilm production. Transcription of adhesin genes saa, iha and lpfO113 were investigated by RT-PCR, being the majority of the strains positive in such assays. Once more, there was no correlation between the RT-PCR results and the phenotypic virulence properties investigated. Distinct clusters were identified by PFGE analysis among the studied strains. Genetic similarity indices ranged from 65 to 100% among these clusters. MLST demonstrated the existence of phylogenetic relationship among O113:H21 STEC strains of different origins. These results indicate the presence in our settings of O113:H21 STEC isolates carrying virulence properties commonly found only in O113:H21 clones associated with SHU cases in other countries.
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    Prevalence and characteristics of Shiga toxin-producing Escherichia coli (STEC) strains in ground beef in São Paulo, Brazil
    (Sociedade Brasileira de Microbiologia, 2007-09-01) Bergamini, Alzira Maria Morato; Simões, Marise; Irino, Kinue; Gomes, Tania Aparecida Tardelli [UNIFESP]; Guth, Beatriz Ernestina Cabilio [UNIFESP]; Instituto Adolfo Lutz Setor de Microbiologia de Alimentos Laboratório I de Ribeirão Preto; Instituto Adolfo Lutz Setor de Microbiologia de Alimentos Laboratório I de Campinas; Instituto Adolfo Lutz Setor de Enterobactérias; Universidade Federal de São Paulo (UNIFESP)
    This study aims to assess the prevalence of Shiga toxin-producing Escherichia coli (STEC) in ground beef collected in two cities located in the State of São Paulo, Brazil. A total of 250 samples of raw ground beef were collected in local grocery stores during the period of March to December 2002 in the cities of Ribeirão Preto (114 samples) and Campinas (136 samples), São Paulo State, Brazil. The samples were processed according to standard methods. The resulting 591 E.coli colonies were screened for STEC by hybridization assays using the specific DNA probes, stx1,stx2 and eae. Further characterization of STEC isolates included the search for the ehxA sequence, detection of enterohemolysin and expression of Shiga toxin using the Vero cell assay. STEC isolates belonging to serotypes O93:H19, ONT:HNT, ONT:H7, and O174:HNT we recovered from four samples (3.5%) collected in Ribeirão Preto. All samples from Campinas were negative for STEC. Three of the strains carried stx2 and ehxA sequences while one harbored stx1,stx2 and ehxA sequences. Considering that among foods of animal origin, ground beef is an important vehicle for STEC transmission, these data emphasize the need of a closer surveillance of these microorganisms. They can survive in unfavorable conditions specially when the products are refrigerated or frozen for long periods of time and can be the cause of outbreaks affecting a great number of consumers.