[Ability of Citrobacter freundii strains isolated in acute intestinal infections to produce LT-enterotoxin]

C. freundii enteropathogenic strains were found to be capable of producing choleroform thermolabile enterotoxin. Thus, in the study of 96 C. freundii strains 38 enterotoxin-producing cultures (39.5%) were revealed by means of the molecular-biological techniques and 29 such cultures (30.0%), by means of the radioimmunoassay (RIA). 100% coincidence was noted in the results of tests for enterotoxigenicity, made by means of RIA or hybridization techniques with the use of the LT-probe containing a cloned fragment with the gene coding the synthesis of LT-enterotoxin in enterotoxigenic Escherichia coli. At the same time only 29 out of 38 Citrobacter strains found to be positive in the hybridization tests, yielded the positive result when tested in RIA for the presence of LT-enterotoxin. This fact should be taken into consideration in the determination of enterotoxin-producing cultures isolated in acute enteric infections, as the method of genetic probing is capable of bringing out the genetic information in bacteria even in the absence of its phenotypical expression.