Toxigenic Escherichia coli in calves with diarrhea in Minas Gerais, Brazil

Foram estudadas 165 amostras de Escherichia coli isoladas de 41 bezerros provenientes de 11 rebanhos leiteiros do Estado de Minas Gerais. Sete amostras produziram toxina termoestável. Destas, duas aglutinaram hemácias de cavalo na presença de manose e foram sorologicamente positivas para K99 (FS), uma apresentou aglutinaçäo de hemácias de cavalo e sorologia negativa para K99 (FS) e duas näo aglutinaram hemácias de cavalo e foram sorologicamente positivas para K99 (FS). Vinte e cinco amostras, isoladas de 18 bezerros com idade entre sete e 51 dias, foram produtoras de citotoxinas. Estes resultados indicam maior importância das amostras citotoxigênicas de E. coli sobre as enterotoxigênicas, no Estado de Minas Gerais

Use of an indirect haemagglutination test for the detection of Clostridium perfringens type A enterotoxin.

An indirect haemagglutination (IH) test is described for the detection of Clostridium perfringens type A enterotoxin, produced by strains isolated from human cases of food poisoning and from contaminated food. Though no strict relationship could be observed between titers in the IH test and the time it took mice to die from the intravenous inoculation of mice (IIM test), results of the supernatants examined by both methods demonstrated that the IH test was more sensitive than the IIM one. No unspecific reaction was obtained in the IH with a negative control and the inhibitions of the IH and IIM tests by specific antiserum against C. perfringens enterotoxin showed that the IH test is very specific. The IH assay is recommended for its sensitivity and easy performance by less-equipped laboratories, by these and other data.

[The incidence of enterotoxigenic Escherichia coli, rotavirus and Clostridium perfringens from cases of diarrhea in children, in the region of Campinas, SP, Brazil]. / Incidência de Escherichia coli enterotoxigênica (ETEC), rotavírus e Clostridium perfringens de casos de diarréia em crianças, na região de Campinas, SP, Brasil.

A survey for the detection of enterotoxigenic Escherichia coli (ETEC), rotavirus and enterotoxigenic Clostridium perfringens in diarrheic stools of children up to 2 years old was carried out in the region of Campinas, SP, Brazil. Twenty-seven (20.45%) faecal specimens were positive for ETEC. From these samples 41 strains of ETEC were isolated from which 40 produced only thermolabile (LT) enterotoxin, as detected by a modified radial immune haemolysis test. Among the 183 faecal specimens examined for the detection of rotavirus, 29 (15.84%) were positive when examined by polyacrilamide gel electrophoresis (PAGE) and immunoenzymatic assay (EIA) being 15 (51.7%), derived from stools collected from winter months. All strains of rotavirus belonged to group A and through the PAGE technique, it was observed that the most frequent (9 strains) electrophoretype, according to the adopted classification, was Ib, IIc, IIIb, IVa. Only 113 fecal specimens were examined for the presence of enterotoxigenic C. perfringens. For the detection of enterotoxin in culture supernatants the reverse passive haemagglutination and intravenous inoculation of mice were used. Twelve (10.61%) enterotoxigenic C. perfringens strains were found. Taking into consideration these findings the authors call the attention of the relative value of conventional coprocultures for diagnostic purposes, pointing out the important of establishing simplified methods which would render easier, the detection and identification of the groups of enteropathogenic agents studied in this research.

Evaluation of the Biken test to detect heat-labile (LT) enterotoxin produced by porcine and human Escherichia coli strains.

Fifty-seven strains of enterotoxigenic Escherichia coli isolated from humans and pigs and producing thermolabile (LT) enterotoxin were used to ascertain the efficiency of the Biken test compared to the passive immune haemolysis test (PIH), considered as very sensitive for detecting that enterotoxin. The two assays were carried out using anti-porcine (anti-LTp), anti-human (anti-LTh), anti-cholera toxin (anti-CT) and anti-choleragenoid (anti-Cg) antisera. Our results showed that the Biken test was very irregular, with many false-negative results. Positive results (ranging from 78.9 to 22.8) were dependent upon the antiserum used. Conversely, the PIH test was much more efficient in the detection of LT, since 100% of the LT+ strains were positive in this test whatever the antiserum used.

Escherichia coli enterotoxigenicas e rotavirus detectados em criancas com gastroenterite aguda em Belem, Para. / Enterotoxigenic Escherichia coli isolated from children with acute gastroenteritis, Belem, Para

Procurou-se pesquisar, em Belem do Para, a presenca de Escherichia coli enterotoxigenica e outros enteropatogenos, incluindo agentes virais, nas fezes de 44 criancas de 0 a 5 anos de idade, com quadro diarreico agudo. A presenca de bacterias enteropatogenicas foi investigada pela coprocultura e a pesquisa de rotavirus atraves das tecnicas de ELISA e contra-imunoeletroosmoforese. O isolamento de enterovirus foi feito em cultura de celulas (Vero e HEp 2) e camundongo recem-nascido. Helmintos e protozoarios intestinais foram procurados pelo metodo direto. Trinta e tres (75%) dos casos foram positivos para um ou mais enteropatogenos, sendo 30,3% de etiologia bacteriana, 39,4% de origem viral e 30,3% de infeccao mista. A procura de enterotoxina LT e ST em 153 cepas de E.coli isoladas dos pacientes, foi feita, pelos testes de imuno-hemolise passiva (PIH) e camundongo recem-nascido (Teste de Dean), respectivamente. Cepas enterotoxigenicas de E. coli, em numero de 17 foram isoladas de sete dos 44 pacientes estudados. Em nenhuma amostra ocorreu producao simultanea de duas enterotoxinas

Pesquisa de fatores de virulencia em Yersinia enterocolitica. / Research on virulence factors in Yersinia enterocolitica

Cinquenta amostras de Y. enterocolitica (32 provenientes da colecao do Instituto Pasteur, Paris, pertencentes a diferentes sorotipos, e 18 isoladas no Brasil, pertencentes aos sorotipos 0:3 e 0:5) foram estudadas quanto a invasibilidade, pesquisada pelo teste de Sereny e em celulas HeLa, e quanto a producao de enterotoxinas termolabil (LT) e termoestavel (ST). Tambem foi pesquisada, atraves de provas de hemaglutinacao manose-resistente, a presenca dos antigenos de aderencia CFA/I, CFA/II,K88 e K99. Nenhuma amostra produziu enterotoxina LT ou apresentou hemaglutinacao manose-resistente. Em celulas HeLa o teste foi positivo para 94,4% das amostras isoladas no Brasil e para 68,7% das amostras da colecao do Instituto Pasteur. No teste de Sereny, 77,7% das amostras isoladas no Brasil e 40,6% das amostras do Instituto Pasteur provocaram intensa conjuntivite em cobaios sem, entretanto, provocar a classica ceratoconjuntivite, produzida por amostras virulentas de Shigella.Producao de enterotoxina ST foi observada em 18,0% das amostras. Tanto a invasibilidade como a producao de ST foram observadas em diferentes sorotipos