title: cfr-mediated linezolid-resistant clinical isolates of methicillin-resistant coagulase-negative staphylococci from China.
abstract: Three linezolid-resistant coagulase-negative staphylococci (LR-CoNS), including two Staphylococcus cohnii and one Staphylococcus capitis, were isolated from 1104 clinical staphylococcal isolates across China in 2013-2014. Antibiotic susceptibilities of the bacteria were determined by the agar dilution method. PCR and DNA sequencing were performed to determine the potential molecular mechanism of linezolid resistance. The two linezolid-resistant S. cohnii isolates were subjected to pulsed-field gel electrophoresis (PFGE) to investigate their genetic relatedness. Primer walking, S1 nuclease PFGE and Southern blot hybridisation were conducted to ascertain the location and environment of the cfr gene. All three isolates were positive for the cfr gene. Amino acid mutations S158F and S158Y in the ribosomal protein L3 were identified in S. cohnii 13B289 and 13L105, respectively, both of which also had an additional substitution (D159Y) in L3. PFGE indicated that the two S. cohnii isolates belonged to diverse clonal strains. S1 nuclease PFGE and Southern blotting experiments indicated that the cfr gene of the three isolates resided on plasmids of similar size (ca. 35.4kb). The cfr-harbouring segments of S. capitis 13G350 and S. cohnii 13L105 were identical to plasmid pSS-01 reported previously. The cfr-carrying fragment of S. cohnii 13B289 was indistinguishable from the formerly described plasmid pSS-02. In conclusion, the presence of the cfr gene located on a plasmid was the main mechanism contributing to resistance to linezolid in the three staphylococcal isolates. Hence, timely detection and judicious use of antibiotics are essential to prevent further transmission of this resistance mechanism.
authors.affiliation: Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, People's Republic of China.
authors.forename: Yunjia
authors.initials: Y
authors.lastname: Song
authors.affiliation: Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, People's Republic of China. Electronic address: lvyuan0901@sina.com.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Lv
authors.affiliation: Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, People's Republic of China.
authors.forename: Lanqing
authors.initials: L
authors.lastname: Cui
authors.affiliation: Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, People's Republic of China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Li
authors.affiliation: Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Ke
authors.affiliation: School of Public Health, Peking University Health Science Center, Beijing, People's Republic of China.
authors.forename: Yixuan
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002681:China; D003030:Coagulase / Q000235:genetics*; D004269:DNA, Bacterial / Q000032:analysis; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000235:genetics*; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial / Q000235:genetics; D019450:Genes, MDR / Q000235:genetics; D006801:Humans; D020071:Interspersed Repetitive Sequences / Q000235:genetics; D000069349:Linezolid / Q000494:pharmacology*; D016106:Methicillin Resistance / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D000090822:Ribosomal Protein L3; D012269:Ribosomal Proteins / Q000235:genetics; D013203:Staphylococcal Infections / Q000382:microbiology; D013210:Staphylococcus / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D003030:Coagulase; D004269:DNA, Bacterial; C000716547:RPL3 protein, human; D000090822:Ribosomal Protein L3; D012269:Ribosomal Proteins; D000069349:Linezolid
keywords: Coagulase-negative staphylococci; Genetic environment; LR-CoNS; Linezolid resistance; Plasmid; cfr