Amino acid substitutions in the VanS sensor of the VanA-type vancomycin-resistant Enterococcus strains result in high-level vancomycin resistance and low-level teicoplanin resistance.
The vancomycin-resistant enterococci GV1, GV2 and GV3, which were isolated from droppings from broiler farms in Japan have been characterized as VanA-type VRE, which express high-level vancomycin resistance (256 or 512 microg ml(-1), MIC) and low-level teicoplanin resistance (1 or 2 microg ml(-1), MIC). The vancomycin resistances were encoded on plasmids. The vancomycin resistance conjugative plasmid pMG2 was isolated from the GV2 strain. The VanA determinant of pMG2 showed the same genetic organization as that of the VanA genes encoded on the representative transposon Tn1546, which comprises vanRSHAXYZ. The nucleotide sequences of all the genes, except the gene related to the vanS gene on Tn1546, were completely identical to the genes encoded on Tn1546. Three amino acid substitutions in the N-terminal region of the deduced VanS were detected in the nucleotide sequence of vanS encoded on pMG2. There were also three amino acid substitutions in the vanS gene of the GV1 and GV3 strains in the same positions as in the vanS gene of pMG2. Vancomycin induced the increased teicoplanin resistance in these strains.
Hashimoto
Y
Y
Department of Microbiology, Gunma University School of Medicine, Showa-machi 3-39-22, Maebashi, Gunma, Japan. yasuike@sb.gunma-u.ac.jp
Tanimoto
K
K
Ozawa
Y
Y
Murata
T
T
Ike
Y
Y
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D019729:Carbon-Oxygen Ligases / Q000235:genetics; D002645:Chickens; D004251:DNA Transposable Elements; D004352:Drug Resistance, Microbial / Q000235:genetics; D016983:Enterococcus / Q000187:drug effects* / Q000235:genetics; D005243:Feces / Q000382:microbiology; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology / Q000662:veterinary; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D011201:Poultry Diseases / Q000382:microbiology; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017334:Teicoplanin / Q000494:pharmacology*; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics*; D020713:Vancomycin Resistance / Q000235:genetics*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D014157:Transcription Factors; C071437:VanA ligase, Bacteria; C073901:VanS protein, Enterococcus; D017334:Teicoplanin; D011494:Protein Kinases; D019729:Carbon-Oxygen Ligases