RESUMEN
The authors examined 250 children suffering from various acute gastrointestinal diseases, and 100 healthy children. Positive cultures of bacteria belonging to the Citrobacter genus were obtained in 38% of the patients and in 20% of the healthy persons. There were revealed no cultural or biochemical differences between the strains isolated from the sick and healthy individuals. There were revealed no cultural or biochemical differences between the strains isolated from the sich and healthy persons. A total of 189 strains were identified serologically. Serological types 01, 03, 04, 08, 021, 022, the ones most frequently encountered in sick children, were absent or rarely found in the healthy. Sensitivity of the majority of the strians to the main antibiotics used in medical practice was weak; the strain isolated from the sick and healthy children failed to differ by the antibiotic sensitivity.