Activity of telithromycin against multi-drug resistant Streptococcus pneumoniae and molecular characterization of macrolide and tetracycline resistance determinants

luated in 26 multi-drug resistant (MDR) Streptococcus pneumoniae strains collecteddurìng 2002-2003 as part of thè ongoing PROTEKT (Prospective ResistantOrganism Tracking and Epidemiology for thè Ketolide Telithromycin) ItalianSurveillance Program. The strains were characterìzed for their susceptibility toantibiotics both at thè phenotypic and genotypic levels; furthermore, thè associationof erm(B), me/[A) class and tet(M) genes, as well as thè mobile elements carryingthem were determined. The strains in this study were resistant to penicillin(MIC ;>2 mg/1) in 23.1% of cases, resistant to tetracycline in 88.4%, to cotrimoxazolein 34.6% and cefuroxime in 26.9% while only telithromycin and levofloxacinretained 100% activity against ali microorganisms. Co-existence of different resistancedeterminants was found in 19.2% of ali isolates collected in our laboratory,coming from southern Italy. Twenty-three isolates showing thè MLSB phenotype ofresistance possessìng thè erm(B) gene (88.5%), associated with tet(M), were carriedon thè same Tnl545-like element, while two isolates showing thè M phenotypepossessing thè meflA) gene alone, were carried on Tnl207.1. In only one strainwere mefiE) and fet(M) together carried on Tn2009.