RESUMO
The expression of surface structures and the presence of DNA sequences related to putative virulence factors were investigated in 22 enteroaggregative Escherichia coli strains (EAEC). Fimbria was the most frequent (72.7%) structure identified. Only strains hybridising with the EAEC DNA probe carried aggA, but one strain produced a similar but unrelated bundle-like structure. All probe-positive and 62.5% of the probe-negative strains carried the virulence genes tested; aspU and irp2 prevailed among the former strains. The EAEC probe-positive strains were more diverse, and some of these strains, which promoted cell detachment, also carried the hly and pap sequences, thus suggesting they might represent uropathogenic E. coli.
Assuntos
Proteínas da Membrana Bacteriana Externa/química , Sondas de DNA/genética , Infecções por Escherichia coli/microbiologia , Escherichia coli/química , Escherichia coli/patogenicidade , Variação Genética/genética , Adesinas Bacterianas/análise , Adesinas Bacterianas/química , Adesinas Bacterianas/genética , Proteínas da Membrana Bacteriana Externa/análise , Proteínas da Membrana Bacteriana Externa/genética , Pré-Escolar , Diarreia/microbiologia , Escherichia coli/classificação , Escherichia coli/genética , Fímbrias Bacterianas/genética , Fímbrias Bacterianas/ultraestrutura , Marcadores Genéticos/genética , Genótipo , Testes de Hemaglutinação , Humanos , Lactente , Recém-Nascido , Microscopia Eletrônica , Virulência/genéticaRESUMO
Anaplasma marginale genomic DNA was tested for the presence of repetitive extragenic palindromic (REP) and enterobacterial repetitive intergenic consensus (ERIC)-like sequences in order to evaluate the genetic diversity of multiple A. marginale isolates. A. marginale isolates were obtained from cattle of six different states of Brazil, from the US and an Anaplasma centrale strain was obtained from Uruguay. Patterns obtained from A. marginale isolates varied from 14 to 17 fragments by REP-polymerase chain reaction (PCR) and 6 to 14 fragments by ERIC-PCR. All A. marginale isolates presented a 0.75-kb fragment by REP and two common fragments (0.38 and 1.0 kb) by ERIC-PCR. These two fragments were not detectable in A. centrale. Both methods produced similar patterns (80%) among A. marginale isolates obtained from the same region, although some isolates within regions shared less similarity. Isolates from Parana and Pernambuco, were differentiated by these methods. The study demonstrates the presence of ERIC and REP-like elements in A. marginale isolates and shows that A. marginale isolates and strains can be differentiated by these methods.
Assuntos
Anaplasma/genética , DNA Bacteriano/genética , Anaplasma/classificação , Animais , Brasil , Bovinos , Sequência Consenso , DNA Bacteriano/análise , DNA Intergênico , Enterobacteriaceae/genética , Reação em Cadeia da Polimerase , Sequências Repetitivas de Ácido NucleicoRESUMO
Twenty-four Escherichia coli strains mainly isolated from children with diarrhea in São Paulo, and showing characteristics of enteroaggregative E. coli (EAEC), were characterized by serotyping and outer membrane protein (OMP) profiles. The relationship between these characteristics was evaluated, as well as the usefulness of OMP profiles in the clonal analysis of EAEC strains. All strains presented aggregative adherence to HeLa cells and were classified in two groups based on their interaction with the EAEC DNA probe. A diversity of serotypes and OMP profiles was observed in both groups studied. Although no significant correlation between serotypes and OMP profiles was observed, unique OMP profiles were identified in 80% of the probe-positive strains which were distributed in only 4 OMP profiles. This result may indicate the presence of a few clones in the probe-positive group. On the other hand, probe-negative strains seem to constitute a more diverse group. In general, the observed heterogeneity in serotypes and OMP profiles described in the present study suggest a great genetic diversity in EAEC isolates of either the same or different serotypes and in strains presenting the same EAEC markers identified in our community.