Variación temporal de genotipos y serogrupos de E coli enterohemorrágicos aislados en niños chilenos con infecciones intestinales o síndrome hemolítico urémico / Temporal variation of genotypes and serogroups of enterohemorrhagic E coli isolated from chilean children with intestinal infections or hemolytic-uremic syndrome

RESUMO

Thirty six strains isolated from chilean children with hemolytic-uremic syndrome (8 obtained in 1988-1989, 15 obtained in 1990-1993 and 13 obtained in 1995-1996), 33 strains from asymptomatic children, obtained in similar periods and 30 strains from children with bloody diarrhea, obtained in 1995-1996 were studied. Virulence factors were investigated with a colony hybridization technique using probes that identify virulence genes. Serotypes were identified with commercial antisera. Both SLTI and SLTII genes predominated in strains obtained from children with hemolytic uremic syndrome in 1988-1989 and 1995-1996 and SLTI gene predominated in strains obtained in 1990-1993. Similar temporal variations in virulence genes of strains obtained from asymptomatic children were observed. SLTI/SLTII pattern predominated in strains obtained from children bloody diarrhea and the frequency of 0157 serogroup was lower, compared to strains obtained from children with hemolytic uremic syndrome. There was a temporal variation in toxigenic genotypes of enterohemorrhagic E coli strains, but no association between these genotypes and the risk for hemolitic uremic syndrome was observed