title: Antimicrobial susceptibility patterns and genomic diversity in strains of Streptococcus pyogenes isolated in 1978-1997 in different Brazilian cities.
abstract: Penicillin has been the antimicrobial of choice for the treatment of Streptococcus pyogenes infections for almost six decades. Although penicillin-resistant isolates have not been described to date, clinical failures have been reported after treatment with beta-lactams. In this study, we analysed the antimicrobial susceptibility and genetic diversity of S. pyogenes isolates obtained from healthy carriers or patients in different cities in the south and south east of Brazil. The MICs were determined for penicillin and seven other antimicrobials. Penicillin tolerance was also investigated. Genetic diversity was analysed by PFGE after SmaI fragmentation of the genomic DNA. All 211 isolates tested were susceptible to penicillin (MIC 0.0025-0.02 mg l(-1)). Four isolates were moderately penicillin-tolerant (MBC/MIC = 16 mg l(-1)). Most of the other drugs tested were very active against the strains examined, except for tetracycline, to which 50 % of strains were resistant. We also found extensive genetic diversity, in that 60 different patterns were recognized in the 96 strains studied. Indeed, we found no correlation between tetracycline resistance and clonality. Despite this diversity, some PFGE patterns persisted for up to 18 years and specific clone types were spread over different geographical locations
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Professor Paulo de Góes, Laboratório de Biologia Molecular de Bactérias, CCS, Bloco I, Cidade Universitária, Rio de Janeiro, RJ, 21941-590, Brazil.
authors.forename: Maria Celeste
authors.initials: MC
authors.lastname: Nunes De Melo
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Professor Paulo de Góes, Laboratório de Biologia Molecular de Bactérias, CCS, Bloco I, Cidade Universitária, Rio de Janeiro, RJ, 21941-590, Brazil.
authors.forename: Agnes Marie Sá
authors.initials: AMS
authors.lastname: Figueiredo
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Professor Paulo de Góes, Laboratório de Biologia Molecular de Bactérias, CCS, Bloco I, Cidade Universitária, Rio de Janeiro, RJ, 21941-590, Brazil.
authors.forename: Bernadete Teixeira
authors.initials: BT
authors.lastname: Ferreira-Carvalho
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001938:Brazil; D024901:Drug Resistance, Multiple, Bacterial; D014644:Genetic Variation; D006801:Humans; D008826:Microbial Sensitivity Tests; D013290:Streptococcal Infections / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents