The study was performed in the Czech Republic during 2007 to 2009. Of Escherichia coli isolates from 275 children aged 6 weeks, 36% (n = 177) were resistant to 1 to 7 antibiotics. Of isolates from 253 children aged 6 to 17 years, 24% (n = 205) were resistant to 1 to 5 antibiotics. There was no significant difference in the prevalences of antibiotic-resistant E. coli isolates between these groups of children, even though the consumptions of antibiotics were quite different.