title: A study on erm(B)-mediated MLS resistance in Streptococcus pyogenes clinical isolates.
abstract: The constitutive or inducible macrolide-lincosamide-streptogramin (MLS) phenotype of 30 erm(B)-positive Streptococcus pyogenes isolates was determined by different methods and under various growth conditions and correlated to the sequence of the 5'-untranslated regions of erm(B). The MLS phenotype of one-third of the isolates could not be classified. In liquid medium, some of these isolates responded to induction only during the logarithmic phase of growth, while others expressed clindamycin resistance even under noninducing conditions. By increasing the growth rate, we observed a shift from a constitutive towards an inducible pattern of resistance. All data were confirmed by analysis of the 23S rRNA methylation level. The erm(B)-5'-untranslated region was 99% similar in sequence. In erm(B)-positive S. pyogenes, the MLS phenotype is strongly influenced by culture conditions and control of its expression does not depend exclusively on the sequence of the erm(B)-5'-untranslated region.
authors.affiliation: School of Biosciences and Biotechnology, University of Camerino, via Gentile III da Varano, I-62032 Camerino (MC), Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Rombini
authors.forename: Dezemona
authors.initials: D
authors.lastname: Petrelli
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Bolli
authors.forename: Chi Nhan
authors.initials: CN
authors.lastname: Tran
authors.forename: Maurizio
authors.initials: M
authors.lastname: Falconi
authors.forename: Maria Chiara
authors.initials: MC
authors.lastname: Di Luca
authors.forename: Manuela
authors.initials: M
authors.lastname: Prenna
authors.forename: Sandro
authors.initials: S
authors.lastname: Ripa
authors.forename: Luca Agostino
authors.initials: LA
authors.lastname: Vitali
mesh_terms: D020121:5' Untranslated Regions; D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D055231:Lincosamides / Q000494:pharmacology*; D018942:Macrolides / Q000494:pharmacology*; D008745:Methylation; D008826:Microbial Sensitivity Tests / Q000379:methods; D012338:RNA, Ribosomal, 23S / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013290:Streptococcal Infections / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D025381:Streptogramin B / Q000494:pharmacology*
chemical_list: D020121:5' Untranslated Regions; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D055231:Lincosamides; D018942:Macrolides; D012338:RNA, Ribosomal, 23S; C551474:ermB protein, Streptococcus pyogenes; D025381:Streptogramin B