Detection of a new cfr-like gene, cfr(B), in Enterococcus faecium recovered from human specimens in the United States: Report from The SENTRY Antimicrobial Surveillance Program.
Antimicrob Agents Chemother. 2015 Jul 27;
Authors: Deshpande LM, Ashcraft DS, Kahn HP, Pankey G, Jones RN, Farrell DJ, Mendes RE
Two linezolid-resistant Enterococcus faecium (MICs, 8 μg/ml) isolates from unique patients of a medical center in New Orleans were included in this study. Isolates were initially investigated for the presence mutations in the V domain of 23S rDNA, L3, L4 and L22 ribosomal proteins, as well as cfr. Isolates were subjected to pulsed-field gel electrophoresis (just one band difference) and one representative strain was submitted to whole genomic sequencing. Gene location was also determined by hybridization and cfr genes cloned and expressed in a Staphylococcus aureus background. Both isolates had one out of six 23S rRNA alleles mutated (G2576T), wildtype L3, L4 and L22 sequences, and were cfr-like-positive. The cfr-like sequence was most similar (99.7%) to those found in Peptoclostridium difficile, which shared only 74.9% amino acid identity when compared with the proteins encoded by genes previously identified in staphylococci and non-faecium enterococci; therefore, denominated Cfr(B). When expressed in S. aureus, the protein conferred a resistance profile similar to that of Cfr. Two copies of cfr(B) were chromosomally-located and embedded in a Tn6218 similar to the cfr-carrying transposon described in P. difficile. This study reports the first detection of cfr genes in E. faecium clinical isolates in the USA and characterization of a new cfr variant, cfr(B). cfr(B) has been observed in mobile genetic elements in E. faecium and P. difficile, suggesting potential for dissemination. However, further analysis is necessary to access the resistance levels conferred by cfr(B) when expressed in enterococci.
PMID: 26248384 [PubMed - as supplied by publisher]