title: Emergence of methicillin-resistant coagulase-negative staphylococci resistant to linezolid with rRNA gene C2190T and G2603T mutations.
abstract: The aim of this article were to determinate the mechanism of linezolid resistance in coagulase-negative methicillin-resistant staphylococci from hospitals in the northeast of Brazil. We identified the isolates using VITEK(®) 2 and MALDI-TOF. Susceptibility to antibiotics was measured by the disk-diffusion method and by Etest(®) . Extraction of the whole genome DNA was performed, followed by screening of all the strains for the presence of mecA and cfr genes. The domain V region of 23S rRNA gene was sequenced and then aligned with a linezolid-susceptible reference strain. Pulsed-field gel electrophoresis (PFGE) macro-restriction analysis was performed. Three linezolid-resistant Staphylococcus hominis and two linezolid-resistant Staphylococcus epidermidis strains were analyzed. The isolates showed two point mutations in the V region of the 23S rRNA gene (C2190T and G2603T). We did not detect the cfr gene in any isolate by PCR. The S. hominis showed the same pulsotype, while the S. epidermidis did not present any genetic relation to each other. In conclusion, this study revealed three S. hominis and two S. epidermidis strains with resistance to linezolid due to a double mutation (C2190T and G2603T) in the domain V of the 23S rRNA gene. For the first time, the mutation of C2190T in S. epidermidis is described. This study also revealed the clonal spread of a S. hominis pulsotype between three public hospitals in the city of Natal, Brazil. These findings highlight the importance of continued vigilance of linezolid resistance in staphylococci.
authors.affiliation: Departamento de Microbiologia e Parasitologia, Laboratório de Bacteriologia Médica, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN.
authors.forename: Thiago André
authors.initials: TA
authors.lastname: Cidral
authors.affiliation: Instituto de Microbiologia Paulo de Góes, Centro de Ciências da Saúde, Bloco i, Cidade Universitária, Ilha do fundão, Rio de Janeiro, RJ, Brazil.
authors.forename: Maria Cícera
authors.initials: MC
authors.lastname: Carvalho
authors.affiliation: Instituto de Microbiologia Paulo de Góes, Centro de Ciências da Saúde, Bloco i, Cidade Universitária, Ilha do fundão, Rio de Janeiro, RJ, Brazil.
authors.forename: Agnes Marie Sá
authors.initials: AM
authors.lastname: Figueiredo
authors.affiliation: Departamento de Microbiologia e Parasitologia, Laboratório de Bacteriologia Médica, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN.
authors.forename: Maria Celeste Nunes
authors.initials: MC
authors.lastname: de Melo
mesh_terms: D000900:Anti-Bacterial Agents; D001483:Base Sequence; D003030:Coagulase / Q000096:biosynthesis; D006801:Humans; D000069349:Linezolid / Q000494:pharmacology*; D008712:Methicillin / Q000494:pharmacology*; D016106:Methicillin Resistance / Q000235:genetics; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics*; D017423:Sequence Analysis, RNA; D013212:Staphylococcus epidermidis / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D041181:Staphylococcus hominis / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D003030:Coagulase; D012338:RNA, Ribosomal, 23S; D000069349:Linezolid; D008712:Methicillin
keywords: Coagulase-negative staphylococci; clonal spread; linezolid resistance; rRNA gene C2190T and G2603T mutations