Molecular typing of antimicrobial-resistant Shiga-toxin-producing Escherichia coli strains (STEC) in Brazil

Antimicrobial resistance patterns and molecular characteristics were determined in thirty-two Shiga-toxin-producing Escherichia coli (STEC) strains previously identified in São Paulo State associated with human infections (n = 21) and in cattle feces (n = 11). the highest resistance rates were identified for tetracycline (100%), streptomycin (78%) and trimethoprim sulfamethoxazole (56%). Eleven STEC strains showed resistance to ampicillin and carried bla(TEM) that was confirmed as bla(TEM-1) in one representative isolate. the class 1 integrase gene (intI1) was detected in seven (22%) strains, and most of them belonged to the O111:H8 serotype. the class 1 integron was located on plasmids in five of the seven STEC strains, and conjugation assays confirmed the plasmid support of those resistant determinants. STEC strains were genetically classified into the B I group, and PFGE analysis showed that most of the strains in each serogroup were grouped into the same cluster (80-97% similarity). the presence of a class 1 integron and bla(TEM-1) genes is described for the first time among STEC isolates in Brazil and clearly represents a public health concern. (C) 2010 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Div Infect Dis, BR-04023062 São Paulo, BrazilJMI Labs, N Liberty, IA USAUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Div Infect Dis, BR-04023062 São Paulo, BrazilWeb of Scienc

Escherichia coli Subtilase Cytotoxin

Subtilase cytotoxin (SubAB) is the prototype of a new AB5 toxin family produced by a subset of Shiga toxigenic Escherichia coli (STEC) strains. Its A subunit is a subtilase-like serine protease and cytotoxicity for eukaryotic cells is due to a highly specific, single-site cleavage of BiP/GRP78, an essential Hsp70 family chaperone located in the endoplasmic reticulum (ER). This cleavage triggers a severe and unresolved ER stress response, ultimately triggering apoptosis. The B subunit has specificity for glycans terminating in the sialic acid N-glycolylneuraminic acid. Although its actual role in human disease pathogenesis is yet to be established, SubAB is lethal for mice and induces pathological features overlapping those seen in the haemolytic uraemic syndrome, a life-threatening complication of STEC infection. The toxin is also proving to be a useful tool for probing the role of BiP and ER stress in a variety of cellular functions

Initial adherence of EPEC, EHEC and VTEC to host cells

Initial adherence to host cells is the first step of the infection of enteropathogenic Escherichia coli (EPEC), enterohaemorrhagic Escherichia coli (EHEC) and verotoxigenic Escherichia coli (VTEC) strains. The importance of this step in the infection resides in the fact that (1) adherence is the first contact between bacteria and intestinal cells without which the other steps cannot occur and (2) adherence is the basis of host specificity for a lot of pathogens. This review describes the initial adhesins of the EPEC, EHEC and VTEC strains. During the last few years, several new adhesins and putative colonisation factors have been described, especially in EHEC strains. Only a few adhesins (BfpA, AF/R1, AF/R2, Ral, F18 adhesins) appear to be host and pathotype specific. The others are found in more than one species and/or pathotype (EPEC, EHEC, VTEC). Initial adherence of EPEC, EHEC and VTEC strains to host cells is probably mediated by multiple mechanisms

Genetic Heterogeneity of Shiga Toxin-Producing Escherichia coli Strains Isolated in São Paulo, Brazil, from 1976 through 2003, as Revealed by Pulsed-Field Gel Electrophoresis

The pulsed-field gel electrophoresis (PFGE) patterns of 46 Shiga toxin-producing Escherichia coli (STEC) strains isolated in São Paulo, Brazil, during the period from 1976 to 2003 were compared with those found among 30 non-STEC strains that carried eae and that belonged to the same serogroups as the STEC strains. All except two of the STEC and non-STEC strains of human origin were from sporadic and unrelated cases of infection; two O111 strains originated from the same patient. Multiple PFGE patterns were found among STEC strains of distinct serotypes. Moreover, the PFGE restriction patterns of STEC strains differed substantially from those observed among non-STEC strains of the same serogroup except serotype O26 strains. Based on the indistinguishable PFGE pattern for two O157:H7 STEC strains isolated in the same geographic area at an interval of approximately 15 days and toxin profile data, the first occurrence of an O157:H7 outbreak in Brazil during that period can be suggested. In general, a close relationship between types of intimin, serotypes, and diarrheagenic groups of E. coli was observed. This is the first time that a large collection of STEC strains from Brazil has been analyzed, and a great genetic diversity was shown among O157:H7 and non-O157:H7 STEC strains isolated in São Paulo, Brazil