PFGE genotyping and antibiotic resistance of Lactobacillus distributed strains in the fermented dairy products

Abstract

The aim of this study was to analyze the antibiotic resistance and pulsed-field gel electrophoresis (PFGE) genotypes of Lactobacillus strains present in fermented dairy products available on the Chinese market and to analyze the correlation between these. A total of 33 Lactobacillus strains identified in fermented dairy products were tested for resistance to 16 antibiotics using the broth microdilution method and also analyzed by PFGE. Almost all of the strains were multidrug resistant and showed high resistance rates to fosfomycin (97.0%), chloramphenicol (87.9%), vancomycin (87.9%), ceftriaxone (81.8%), imipenem (66.7%), trimethoprim/sulfamethoxazone (54.6%), tetracycline (33.3%), cefotaxime (21.2%), gentamicin (18.2%), erythromycin (12.1%), gatifloxacin (12.1%), amoxicillin/clavulanic acid (12.1%), rifampin (9.1%), and clindamycin (9.1%). Based on the PFGE results, the 33 strains were subtyped into 17 pulsotypes (PFPs, pulsed-field profiles), of which six were represented by more than one strain each. In conclusion, the Lactobacillus strains identified here in fermented dairy products available on the Chinese market showed a high rate of antibiotic resistance. Lactobacillus strains were genotyped well by PFGE; the resistance patterns of the strains among the same PFP were not necessarily similar to each other. © Springer-Verlag and the University of Milan 2011.