Assessment of antibiotic resistance in probiotic strain Lactobacillus brevis KB290.
Our purpose was to investigate the safety of the probiotic strain Lactobacillus brevis KB290. The European Qualified Presumption of Safety (QPS) evaluation approach was applied to the strain. We determined the strain's antibiotic resistance, verified it at the genetic level, and determined whether it could be transferred to intestinal microflora. Of 14 antibiotics tested, 11 showed MICs within the limits of the QPS criteria. However, the L. brevis KB290 MICs of ciprofloxacin (a fluoroquinolone), tetracycline, and vancomycin were two, four, and eight times, respectively, the breakpoint MICs suggested by the European Scientific Committee on Animal Nutrition, and the MIC of tetracycline was eight times the breakpoint MIC suggested by the European Scientific Panel on Additives and Products or Substances Used in Animal Feed. Using analysis of gapped-genome sequences, we found no known transferable determinants for tetracycline or vancomycin resistance, and we found no mutations in the quinolone resistance-determining regions of the genes encoding GyrA or ParC for ciprofloxacin resistance associated with insertion sequences, integrons, or transposons. These data were confirmed by using PCR primers specific for the respective genes. We assessed the transferability of the resistance traits in conjugation experiments with enterococci and obtained no transconjugants, strongly suggesting that the resistance traits were not transferable. This study demonstrated that the antibiotic resistance observed in L. brevis KB290 was due not to dedicated mechanisms but to intrinsic resistance. According to the QPS criteria, these results provide safety assurance for the ongoing use of L. brevis KB290 as a probiotic.
Probiotics Research Department, Research Institute, Kagome Company, Limited, 17 Nishitomiyama, Nasushiobara, Tochigi, 329-2762, Japan. Masanori_Fukao@kagome.co.jp
Masanori
M
Fukao
Haruyoshi
H
Tomita
Takafumi
T
Yakabe
Takahiro
T
Nomura
Yasuyoshi
Y
Ike
Nobuhiro
N
Yajima
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003227:Conjugation, Genetic; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D052196:Levilactobacillus brevis / Q000187:drug effects* / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D019936:Probiotics; D016415:Sequence Alignment
D000900:Anti-Bacterial Agents