title: Macrolide resistance genotypes and phenotypes among erythromycin-resistant clinical isolates of Staphylococcus aureus and coagulase-negative staphylococci, Italy.
abstract: One hundred macrolide-resistant staphylococcal isolates from clinically relevant infections in Italy during a 19-month period were studied. Four distinct resistance phenotypes were observed using the triple-disk induction test (erythromycin, clindamycin, telithromycin): the cMLS(B) phenotype (24 isolates); the iMLS(B) phenotype (41 isolates); the MS phenotype (three isolates); and the iMTS phenotype (erythromycin-induced telithromycin resistance) (32 isolates). ermC and ermA genes predominated within erythromycin-resistant Staphylococcus aureus isolates with iMLS(B) phenotype and cMLS(B) phenotype, respectively. Among erythromycin-resistant CoNS isolates, half of the strains showed the iMTS or MS/msrA association, and ermC gene predominated among isolates with MLS(B) phenotype. By pulsed-field gel electrophoresis, high genetic heterogeneity was observed among the isolates studied. Both independent acquisition of macrolide resistance genes and spread of specific resistant clones were observed. Association between certain clonal types and specific types of infection could be detected. To our knowledge, this is the first report on characterization of erythromycin-resistant staphylococci in Italy.
authors.affiliation: Dipartimento di Scienze Biomediche, Università Campus Bio-Medico, Rome, Italy. g.gherardi@unicampus.it
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gherardi
authors.forename: Lucia
authors.initials: L
authors.lastname: De Florio
authors.forename: Giulia
authors.initials: G
authors.lastname: Lorino
authors.forename: Laura
authors.initials: L
authors.lastname: Fico
authors.forename: Giordano
authors.initials: G
authors.lastname: Dicuonzo
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D007558:Italy; D018942:Macrolides / Q000494:pharmacology*; D008780:Methyltransferases / Q000235:genetics; D008826:Microbial Sensitivity Tests / Q000379:methods; D010641:Phenotype; D013203:Staphylococcal Infections / Q000382:microbiology*; D013210:Staphylococcus / Q000187:drug effects* / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D018942:Macrolides; D008780:Methyltransferases; C431709:ErmA protein, Bacteria; C035181:rRNA (adenosine-O-2'-)methyltransferase