title: Resistance to linezolid in Staphylococcus spp. clinical isolates associated with ribosomal binding site modifications: novel mutation in domain V of 23S rRNA.
abstract: Linezolid is the main representative of the oxazolidinones, introduced in 2000 in clinical practice to treat severe Gram-positive infections. This compound inhibits protein synthesis by binding to the peptidyl transferase centre of the 50S bacterial ribosomal subunit. The aim of this study was to characterize 12 clinical strains of linezolid-resistant Staphylococcus spp. isolated in Northern Italy. All isolates of Staphylococcus spp. studied showed a multi-antibiotic resistance phenotype. In particular, all isolates showed the presence of the mecA gene associated with SSCmec types IVa, V or I. Mutations in domain V of 23S rRNA were shown to be the most prevalent mechanism of linezolid resistance: among these a new C2551T mutation was found in S. aureus, whilst the G2576T mutation was shown to be the most prevalent overall. Moreover, three S. epidermidis isolates were shown to have linezolid resistance associated only with alterations in both L3 and L4 ribosomal proteins. No strain was shown to harbor the previously described cfr gene. These results have shown how the clinical use of linezolid in Northern Italy has resulted in the selection of multiple antibiotic-resistant clinical isolates of Staphylococcus spp., with linezolid resistance in these strains being associated with mutations in 23S rRNA or ribosomal proteins L3 and L4.
authors.affiliation: Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
authors.forename: Rosario
authors.initials: R
authors.lastname: Musumeci
authors.affiliation: Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Calaresu
authors.affiliation: Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
authors.forename: Jolanda
authors.initials: J
authors.lastname: Gerosa
authors.affiliation: Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Oggioni
authors.affiliation: Laboratory of Microbiology, San Gerardo Hospital, Monza.
authors.forename: Simone
authors.initials: S
authors.lastname: Bramati
authors.affiliation: Central Biochemistry and Microbiology Laboratory, Giannina Gaslini Institute, Genoa.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Morelli
authors.affiliation: Department of Biomedical Sciences, University of Sassari, Sassari, Italy.|Hygiene Unit, University Hospital of Sassari, Sassari, Italy.
authors.forename: Ida
authors.initials: I
authors.lastname: Mura
authors.affiliation: Department of Biomedical Sciences, University of Sassari, Sassari, Italy.|Hygiene Unit, University Hospital of Sassari, Sassari, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Piana
authors.affiliation: Hygiene Unit, University Hospital of Sassari, Sassari, Italy.
authors.forename: Bianca Maria
authors.initials: BM
authors.lastname: Are
authors.affiliation: Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
authors.forename: Clementina Elvezia
authors.initials: CE
authors.lastname: Cocuzza
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D000069349:Linezolid / Q000494:pharmacology*; D009154:Mutation; D012338:RNA, Ribosomal, 23S / Q000235:genetics*; D013203:Staphylococcal Infections / Q000382:microbiology*; D013210:Staphylococcus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D012338:RNA, Ribosomal, 23S; D000069349:Linezolid
keywords: HIV; Long-lasting infection; Recent infection; Viral strains