Based on a grant project „Use and importance of epidemiological markers in Salmonella enteritidis and Salmonella typhimurium in the spread of salmonelloses in children under two years of age“ implemented in 1995 to 1997, the authors investigated epidemiological markers in 1 186 salmonella isolates; the strains were isolated from faeces of 838 sick children, from 266 faeces of their contacts, from 49 specimens of incriminated foods and from 33 smears from the children’s environment. Of 1 186 Salmonella isolates 999 were strains of S. enteritidis, 39 strains of S. typhimurium and 148 strains were not identified. The markers of Salmonella isolates were investigated from the aspect of biotyping – 98% S. enteritidis were formed by the biovar Jena. 2% by biovar Essen; sensitivity to antibiotics – 94.5% Salmonella strains were sensitive to 12 selected antibiotics, 2.9% were resistant and in 2.6% the resistance was in the intermediate zone; phagotyping – in 808 strains of S. enteritidis PT 8 – 88% predominated, in S. typhimurium DT 104 and DT 141; assessment of plasmid profiles – in strains of S. enteritidis plasmid 55 kb predominated, in three strains of S. typhimurium a plasmid size 95 kb; virulence – was compared in 43 strains isolated from hospitalized children with a severe clinical course with 39 strains from children treated at home. In vitro tests revealed that hospitali- zation of affected children was associated with virulence of the strains (SE phagotype 8) and not with age. The presented results are discussed with regard to the epidemiological situation in the Czech Republic and in the world.

        Key words: Salmonella enteritidis – markers – Salmonella typhimurium DT 104.