THE AIM

Of the work is to estimate the potential of transfer of resistance genes from Lactobacillus fermentum 5-1 to the gram-negative intestinal microbiota.

MATERIALS AND METHODS

The sensitivity to antibiotics was assessed using the gradient agar method and microdilution method. Detection of antibiotic resistance (AR) genes in bacterial genomic DNA was carried out using PCR, followed by Sanger sequencing of the amplicons and BLASTn sequence analysis. Acinetobacter baumannii, Citrobacter freundii, and Escherichia coli possessed neither phenotypic nor genotypic resistance to tetracycline and therefore were selected among nine gram-negative strains as recipients of AR genes. The transferability of AR genes from L. fermentum 5-1 to these bacteria was studied under co-cultivation in a simulated colonic environment, in filter mating experiments, and using transformation of bacteria by electroporation.

RESULTS

Based on the MIC values, we found that this strain was resistant to vancomycin (MIC=256 μg/mL), ciprofloxacin (MIC=64 μg/mL), aminoglycosides (MIC=54—256 μg/mL), chloramphenicol (MIC=8 μg/mL), sensitive to ampicillin (MIC=0.5 μg/mL), rifampicin (MIC=2 μg/mL), and cefotaxime (MIC=0.12 μg/ml), had an intermediate (low) resistance to erythromycin (MIC=1 μg/ml) and tetracycline (MIC=8 μg/ml). Using PCR analysis in the chromosomal DNA of L. fermentum 5-1, we detected the erythromycin resistance gene ermB, while in plasmid DNA two tetracycline resistance genes, tetM and tetK, were identified. Moreover, we demonstrated that L. fermentum 5-1 could transfer their tetK gene to C. freundii via electroporation and transformation with the plasmid DNA of the lactobacilli.

CONCLUSION

Our results evidence that lactobacilli can negatively contribute to the antibiotic resistance problem and warrant tightening of the control over the practical use of LAB.