title: Molecular characterization of methicillin-resistant Staphylococcus aureus resistant to tigecycline and daptomycin isolated in a hospital in Brazil.
abstract: We report the molecular characterization of methicillin-resistant Staphylococcus aureus (MRSA) with resistance to tigecycline and to daptomycin isolated from intensive-care-unit patients in Brazil over a 6-month period. Thirty-six isolates (25 from infection sites, 11 from nasal sites) recovered from 23 patients who presented with MRSA infection during this period were characterized by pulsed-field gel electrophoresis, multilocus sequence typing, staphylococcal cassette chromosome mec (SCCmec) typing, and antimicrobial susceptibility profiling. Ten isolates from six patients and two isolates from different patients were resistant to tigecycline and daptomycin, respectively. Eight pulsotypes were identified and one, type A, accounted for 21 isolates from 12 patients; type A isolates were SCCmecII as were a further nine isolates of other pulsotypes. All but four of the total isolates were sequence type (ST) 5 or ST105 and classified as clonal complex (CC) 5; the historically prevalent lineage in Brazil, ST239-SCCmecIII, was identified in only three patients. Tigecycline-resistant strains were all ST105-SCCmecII and two patients were nasally colonized by strains of the same pulsotype found in infection sites. Two ST5-SCCmecII were daptomycin resistant after 48 h incubation. The origin and mechanism of these resistant strains remains unknown and further studies are warranted to determine whether such clones are becoming endemic in Brazilian hospitals and to assess their impact on infection control practice.
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brasil.
authors.forename: A N G
authors.initials: AN
authors.lastname: Dabul
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brasil.
authors.forename: I L B C
authors.initials: IL
authors.lastname: Camargo
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D001938:Brazil / Q000453:epidemiology; D004269:DNA, Bacterial / Q000235:genetics; D017576:Daptomycin / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006761:Hospitals; D006801:Humans; D007362:Intensive Care Units; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology; D017720:Molecular Epidemiology; D046915:Penicillin-Binding Proteins; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000235:genetics; D000078304:Tigecycline
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus; D000078304:Tigecycline; D008911:Minocycline; D017576:Daptomycin