Biomedical subjects

R Giraldi

Publications and source records attributed to R Giraldi.

5 recordsLinked to original sources

PubMed1997

Culture supernatant of Shiga toxin-producing Escherichia coli strains provoke fluid accumulation in rabbit ileal loops.

Production of Shiga toxin (Stx) in Escherichia coli strains belonging to serogroups O26, O111, and O157 was evaluated in the rabbit ileal loop assay and results were compared to those using tissue culture assays and DNA hybridization with specific probes for Stx1 and Stx2. All 14 Shiga toxin-producing E. coli strains tested provoked fluid accumulation in the rabbit intestinal loop. Eleven strains hybridized with Stx1 probe, one strain with Stx2 and two strains with both probes. Filtered culture supernatants of all E. coli strains presented cytotoxic effects in both HeLa and Vero cells. In this study, we found a strong association between the production of Stx and its effect in an animal model. This is the first description of high-level Stx-producing E. coli O111ac isolated in Brazil.

Animals↗

PubMed1996

Diffuse adherence, ST-I enterotoxin and CFA/IV colonization factor are encoded by the same plasmid in the Escherichia coli O29:H21 strain.

Escherichia coli O29:H21 is a human enterotoxigenic serotype that produces heat-stable (ST-I) enterotoxin, adheres diffusely to HeLa cells, and presents colonization factor antigen IV (CFA/IV) composed of CS5CS6 surface antigens. In one strain studied the genes for diffuse adherence and CFA/IV (CS5CS6) production were found to be present in the same plasmid encoding ST-I. The virulence plasmid (Ent) presented two unrelated basic replicons homologous to repFIC and repW. Gene(s) encoding diffuse adherence did not share homology with the probe for F1845 fimbrial adhesin which is responsible for this phenotype in other E. coli strains. Ent plasmids containing genes for diffuse adherence have not been described previously.

Acridine Orange↗

PubMed1994

Survey of cytotoxin production among Escherichia coli strains characterized as enteropathogenic (EPEC) by serotyping and presence of EPEC adherence factor (EAF) sequences.

A total of 108 Escherichia coli strains characterized as enteropathogenic (EPEC) by serotyping and the presence of EPEC adherence factor (EAF) sequences were examined for cytotoxin production by cell line assays and colony hybridization with Shiga-like toxin (SLT) probes. Cytolethal distending toxin (CLDT) production was found in three (2.8%) strains belonging to serotype O86:H34, while one O111ab:NM strain hybridized with a SLT-II probe but did not express any cytotoxic activity. All four strains showed localized adherence to HeLa cells and hybridized to an E. coli attaching-effacing gene (eae) probe. The CLDT-producing strains had multiple plasmids and some were present in all strains, including a plasmid of approximately 54 MDa that hybridized with the EAF probe.

Adhesins, Escherichia coli↗

PubMed1993

Presence of colonization factor antigen IV (CS5CS6) in O29:H21 enterotoxigenic Escherichia coli isolated from children with diarrhea in Brazil.

1. Enterotoxigenic Escherichia coli (ETEC) strains belonging to serotype O29:H21 were analyzed for the presence of colonization factor antigens (CFA). 2. CFA/IV was detected in all twelve strains studied, and immunological analysis demonstrated that it was composed of coli surface antigens 5 (CS5) and 6 (CS6) presenting molecular weights of approximately 21 kDa and approximately 16 kDa, respectively. 3. CS6 antigenic homology was observed between O29:H21 and reference strains E11881C and E17018A. 4. CS6 of the O29:H21 strains was composed of two peptide bands, similar to the reference strain E17018A.

Bacterial Proteins↗

PubMed1990

Production of Shiga-like toxin among Escherichia coli strains and other bacteria isolated from diarrhea in São Paulo, Brazil.

An elevated level of Shiga-like toxin I (SLT-I) production was found in 1 of 466 Escherichia coli strains studied. Among the 34 sonic lysates obtained from classical enteropathogenic E. coli, 5 produced SLT-I. The Aeromonas, Citrobacter, Edwardsiella, Enterobacter, Klebsiella, Proteus, Providencia, Pseudomonas, Salmonella, Serratia, Shigella, Yersinia, and Vibrio strains also studied were not SLT producers, except for a Shigella dysenteriae type 1 strain. Although SLT-I-producing E. coli strains were isolated from diarrhea, they seem to be an uncommon cause of disease in children less than 1 year old in our community.

Bacterial Toxins↗