Twenty-nine Shiga toxin-producingShiga toxin-producing Escherichia coli (STEC) can cause a broad spectrum of human illness ranging from uncomplicated diarrhea to hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS) (14). E. coli O157:H7 is by far the most important STEC serotype in the world and has been associated with numerous outbreaks and many sporadic cases of HC and HUS (20). However, infections with other non-O157 STEC serotypes have been increasingly reported in many countries (2,3,22). Currently more than 100 different non-O157 STEC serotypes have been isolated from human infections. Unlike with O157:H7, outbreaks caused by non-O157 STEC have rarely been reported, and these strains have been more frequently associated with sporadic cases of diarrhea, HC, and HUS. Moreover, in many countries, non-O157 strains are more commonly isolated from patients with diarrhea or HUS than are O157 STEC strains (3, 5, 23). The major virulence trait of these bacteria is the production of one or more Stx types (Stx1, Stx2, or Stx2 variants) (20). Additional factors, produced mainly by strains in straight association with human disease and collectively referred to as enterohemorrhagic E. coli (EHEC), include intimin and enterohemolysin (1,20). Other putative virulence factors include the enteroaggregative E. coli heat-stable enterotoxin (EAST-1), encoded by astA (25), particularly in O157:H7 and O26:H11 strains and in some other STEC serotypes. In Brazil, the studies conducted so far that searched for STEC in human diarrheal disease have investigated a limited number of strains and have described the isolation of a few non-O157 STEC strains (7,12,16). The isolation of O157:H7 strains from patients with bloody diarrhea as well as one with HUS related to O26:H11 infection was only recently reported in Brazil (15,19).The purpose of this study was to search for STEC in a collection of 2,607 E. coli isolates, most of them belonging to important serogroups increasingly associated with HUS and HC in other countries. The main virulence factors, biotypes, and susceptibility to antimicrobial agents of the STEC strains identified were characterized.The E. coli strains studied belonged to the collection of Instituto Adolfo Lutz, a Central Public Health Laboratory in São Paulo, Brazil, and national center for E. coli serotyping, and were isolated between 1976 and 1999, mainly from children (0 to 5 years old) with diarrhea (2,549 strains); the remaining 58 E. coli strains were isolated from immunocompromised adult patients with diarrhea (mainly human immunodeficiency virus positive) over the same period. Each strain was derived from one patient. Except for diarrhea, no other information regarding the clinical aspects of the patients were available. None of the strains belonging to the enteropathogenic E. coli (EPEC) serogroups carried the EAF sequence (EPEC adherence factor) as assayed by hybridization assays with a specific DNA probe (13). The remaining strains outside the EPEC serogroups did not belong to the enteroinvasive ...

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Whole genome sequencing (WGS) has been used as a powerful technology for molecular epidemiology, surveillance, identification of species and serotype, identification of the sources of outbreaks, among other purposes. In Brazil, there is relatively few epidemiological data on Salmonella. In this study, 90 Salmonella Typhimurium strains had their genome sequenced to uncover the diversity of Salmonella Typhimurium isolated from humans and food, between 1983 and 2013, from different geographic regions in Brazil based on single nucleotide polymorphism (SNP) analysis. A total of 39 resistance genes were identified, such as aminoglycoside, tetracycline, sulfonamide, trimethoprim, beta-lactam, fluoroquinolone, phenicol and macrolide, as well as the occurrence of point mutations in some of the genes such as gyrA, gyrB, parC and parE. A total of 65 (72.2%) out of 90 S. Typhimurium strains studied were phenotypically resistant to sulfonamides, 44 (48.9%) strains were streptomycin resistant, 27 (30%) strains were resistant to tetracycline, 21 (23.3%) strains were gentamicin resistant, and seven (7.8%) strains were resistant to ceftriaxone. In the gyrA gene, it was observed the following amino acid substitutions: Asp(87)→Gly, Asp(87)→Asn, Ser(83)→Phe, Ser(83)→Tyr. Phylogenetic results placed the 90 S. Typhimurium strains into two major clades suggesting the existence of a prevalent subtype, likely more adapted, among strains isolated from humans, with some diversity in subtypes in foods. The variety and prevalence of resistant genes found in these Salmonella Typhimurium strains reinforces their potential hazard for humans and the risk in foods in Brazil.

To study the main enteropathogens causing diarrhea in the region of Ribeirão Preto regarding serogroups and serotypes, the feces of 1836 children under 10 years old, from both sexes, attack of acute gastroenteritis, were analysed during a period of 4 years in Adolfo Lutz Institute - Ribeirão Preto, SP. The pathogens identified by standard methods were the following: Escherichia coli, Salmonella spp., Shigella spp., Campylobacter spp., Yersinia spp., and Cryptosporidium spp. Positive samples were 22.8% (419) with 1.7% association of pathogens. Larger isolates were mainly from children 0 to 11 months old. Enteropathogenic E. coli (EPEC) was most frequent (8.7%) with predominance of serogroup O119 (40.2%), followed by Shigella (6.2%), 63.6% of which S. sonnei.

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