This study was conducted to characterize the virulence potential of 59 Escherichia coli strains carrying EAE and lacking the enteropathogenic E. coli adherence factor and Shiga toxin probe sequences. In hybridization studies, all strains carried the locus of enterocyte effacement (LEE)-associated DNA sequences. Of the other 15 virulence DNA sequences tested, HLY was the most frequent (44.1%); 17 combinations of these sequences were found, but strains carrying EAE only (EAE profile) were the most frequent (35.6%). Except for 1 cytodetaching strain, all others adhered to HeLa and Caco-2 cells, most of which (approximately 75.0%) showed variations of the localized adherence pattern. Actin accumulation was detected in 75.9% of the nondetaching strains. Most strains had LEE, probably inserted in pheU (49.2%), and presented a nontypeable intimin (83.1%). Translocated intimin receptor-derived DNA sequences correlated with enteropathogenic and enterohemorrhagic E. coli in 61.0% and 32.0% of the strains, respectively. Thirty-five different serotypes were found. Only strains with the EAE profile were associated with diarrhea (P=.039).

Serovars of a total of 5,490 Salmonella strains isolated during the period of 1991-95, from human infections (2,254 strains) and from non-human materials (3,236 strains) were evaluated. In the studied period, 81 different serovars were determined among human isolates. Salmonella Enteritidis corresponded to 1.2% in 1991, 2% in 1992, 10.1% in 1993, 43.3% in 1994, and 64.9% in 1995 of all isolates. A significant rise on the isolation of this serovar was seen since 1993 linked to food poisoning outbreaks. It is reported also an increase on the isolation of S. Enteritidis from blood cultures, associated mainly with patients with immunodeficiency syndrome. S. Enteritidis was prevalent among one hundred and thirty different serovars isolated from non-human sources. Increasing number of isolation of this serovar was seen from shell eggs, breeding flocks and from environmental samples. It is also reported a contamination of commercial feed stuffs by S. Enteritidis which represents a major concern for Brazilian poultry industry.

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 ...

SUMMARYSalmonellosis remains an important cause of diarrheal illness in humans in São Paulo State, Brazil. In this study were identified 3554 Salmonella isolates from human infections, during the period 1996-2003. Among 68 different serovars determined, S. Enteritidis was the most frequent one in gastrointestinal and extra-intestinal infections accounting for 67.4% of all isolates. S. Typhimurium and S. enterica subsp. enterica (4,5,12:i:-) were most frequently isolated from children aged < 1-4 year-old, in contrast, people with S. Enteritidis infections were most likely to be 20-50 year-old. In our geographic area the continued laboratorial surveillance of salmonellosis, including serotyping, has showed the trends in Salmonella serovars causing infections in humans throughout the time.

From 1950 to 1990 a total of 45,862 strains (31,517 isolates from human sources, and 14,345 of non-human origin) were identified at Instituto Adolfo Lutz. No prevalence of any serovars was seen during the period 1950-66 among human sources isolates. Important changing pattern was seen in 1968, when S. Typhimurium surprisingly increased becoming the prevalent serovar in the following decades. During the period of 1970-76, S. Typhimurium represented 77.7% of all serovar of human origin. Significant rise in S. Agona isolation as well as in the number of different serovars among human sources strains were seen in the late 70' and the 80's. More than one hundred different serovars were identified among non-human origin strains. Among serovars isolated from human sources, 74.9%, 15.5%, and 3.7% were recovered from stool, blood, and cerebrospinal fluid cultures, respectively. The outbreak of meningitis by S. Grumpensis in the 60's, emphasizes the concept that any Salmonella serovars can be a cause of epidemics, mainly of the nosocomial origin. This evaluation covering a long period shows the important role of the Public Health Laboratory in the surveillance of salmonellosis, one of the most frequent zoonosis in the world.