[Genetic nature of the antibiotic-resistance of Lactobacillus]

One hundred and forty one strains of Lactobacillus were isolated from intestinal contents of persons being in long-term contact with antibiotics. Their sensitivity to 10 chemotherapeutic agents was studied with the method of serial dilutions in solid media under aerobic and anaerobic conditions. A single administration of antibiotics in the therapeutic doses led to selection of Lactobacillus polyresistant strains in the intestine of rats. The antibiotic resistance spectrum of the Lactobacillus cultures was unstable and changed under nonselective conditions of their storage and after their lyophilization or short-term exposure to heat. The changes in the resistance spectrum were accompanied by changes in the plasmid profile. An electrophoretogram of plasmid DNA from the intestinal isolate L plantarum MT205 is presented. Relation between the marker of lincomycin resistance and the presence of plasmid DNA weighing 130 kb was shown in the isolate.