Alterations in regulatory regions of erm(B) genes from clinical isolates of enterococci resistant to telithromycin.
We determined rates of resistance to the ketolide telithromycin in 56 Enterococcus faecalis isolates and 44 Enterococcus faecium isolates collected from hospitals in Korea between 2005 and 2006. Twenty nine (51.8%) isolates of E. faecalis and 35 (79.5%) isolates of E. faecium were resistant to telithromycin (minimum inhibitory concentrations, ≥ 4 μg/mL). All of the telithromycin-resistant E. faecalis carried the erm(B) gene only. Of the telithromycin-resistant E. faecium, 29 resistant strains carried erm(B) only, the other six carried erm(A) and erm(B) together. The nucleotide sequence of the erm(B) regulatory regions from 29 E. faecalis and 29 E. faecium isolates with erm(B) only was analyzed. Five types of alterations were detected. The first and second types had point mutations that destabilize the secondary structure of erm(B) mRNA sequestering the translation initiation region of the structural gene. The third type was identical to erm(Bv1), a previously reported variant of erm(B) with different induction specificity. The fourth and fifth types had point mutations within the critical sequence for induction and a point mutation destabilizing the stem-loop of erm(B) mRNA sequestering the translation initiation region of the structural gene.
Department of Herbal Skin Care, College of Herbal Bio-Industry, Daegu Haany University, Gyeongsan, 712-715, Korea.
Yu-Hong
YH
Min
Eun-Jeong
EJ
Yoon
Ae-Ran
AR
Kwon
Mi-Ja
MJ
Shim
Eung-Chil
EC
Choi
D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects / Q000235:genetics*; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics*; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics*; D005798:Genes, Bacterial; D006801:Humans; D048628:Ketolides / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009690:Nucleic Acid Conformation; D017354:Point Mutation; D012045:Regulatory Sequences, Nucleic Acid / Q000187:drug effects / Q000235:genetics; D017422:Sequence Analysis, DNA
D004269:DNA, Bacterial; D048628:Ketolides; C106791:telithromycin