Genotypic and phenotypic characterization of enterotoxigenic Escherichia coli (ETEC) strains isolated in Rio de Janeiro city, Brazil.
Enterotoxigenic Escherichia coli (ETEC) strains have been implicated as important etiological agents of diarrheal disease, especially in developing countries. This group of microorganisms has been associated with a diverse range of genotypic and phenotypic markers. In the present study, 21 ETEC isolates previously defined according to the toxigenic genotypes, were characterized on the basis of O:H typing, cell adherence patterns, and colonization factors (CFs) antigens. Genetic diversity was investigated by random amplification polymorphic DNA (RAPD-PCR), pulsed-field gel electrophoresis (PFGE) and multilocus enzyme electrophoresis (MLEE). LT-I probe-positive isolates belonged to serotypes ONT:HNT, O7:H24, O48:H21, O88:H25, O148:H28, O159:H17 and O159:H21. ST-h probe-positive isolates belonged to serotypes O159:H17, O148:H28 and O6:H-. Serotypes O148:H28, O159:H17 and O6:H- were associated with the CS6, CFA/I and CS1 CS3 antigens, respectively. Most ETEC strains exhibited a diffuse pattern of adherence to cultured epithelial cells. In general, phenotypic and genotypic characteristics correlated well. RAPD-PCR, PFGE and MLEE showed reproducibility and good discriminatory potential. The application of molecular typing systems allowed the detection of significant diversity among the isolates, indicating a non-clonal origin and revealing intra-serotype variation overlooked by classical epidemiological approaches. The phenotypic and genotypic diversity observed lead us to recommend the use of different typing systems in order to elucidate the epidemiology of ETEC infection.
Departamento de Ciências Biológicas, Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, Manguinhos, RJ Brazil. regua@ensp.fiocruz.com.br
Adriana Hamond
AH
Regua-Mangia
Beatriz Cabilio
BC
Guth
João Ramos
JR
da Costa Andrade
Kinue
K
Irino
Ana Beatriz F
AB
Pacheco
Luís Carlos S
LC
Ferreira
Viviane
V
Zahner
Lúcia Martins
LM
Teixeira
D001938:Brazil; D004768:Enterotoxins / Q000378:metabolism; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D036781:Fimbriae Proteins; D014644:Genetic Variation; D005838:Genotype; D010641:Phenotype; D010802:Phylogeny; D019105:Random Amplified Polymorphic DNA Technique; D012703:Serotyping
D004768:Enterotoxins; C022924:colonization factor antigens; D036781:Fimbriae Proteins