ABSTRACT
Enterobacteria, potentially capable of causing infections, were isolated from the feces of 88.7% of young children in the intestinal department of an infectious disease hospital. Opportunistic bacteria were considered to be the causative agents of infections only in cases of their high concentration in the material under test. In about a half of the cases the etiological role of the suspected microorganisms was confirmed by the detection of antibodies in low titers. The presence of maternal antibodies did not interfere with diagnostic procedures. The detection of antibodies to autocultures, even in a single case, is of diagnostic importance in the examination of young children. Autoserologically confirmed mixed infection was found to take a more prolonged course than autoserologically confirmed monoinfection.