The post-antibiotic effects of rokitamycin (a 16-membered ring macrolide) on susceptible and erythromycin-resistant strains of Streptococcus pyogenes.
The post-antibiotic effects (PAEs) on susceptible and erythromycin-resistant strains of Streptococcus pyogenes (M phenotype and inducibly resistant) of rokitamycin and erythromycin were investigated in vitro using microbiological impedance measurement. Exposure of susceptible S. pyogenes strains to 1/4, 1/2, 1 and 2 MIC erythromycin and rokitamycin resulted in PAEs of rokitamycin in the same order of magnitude as those of erythromycin and that were dose dependent. The duration of rokitamycin PAEs in erythromycin-resistant S. pyogenes strains (M phenotype and those with inducible resistance) were comparable with those observed in susceptible strains. This was not the case for erythromycin. The investigation showed that a 16-membered ring macrolide such as rokitamycin has different PAEs from those of a 14-membered ring macrolide such as erythromycin. They also indicated that, as the PAEs of rokitamycin on the M phenotype and inducible resistant strains were comparable with those on susceptible strains, no re-evaluation of therapeutic dosing regimens was required.
Center of Respiratory Pharmacology, Department of Pharmacology, School of Medicine, University of Milan, Via Vanvitelli 32, 20129 Milano, Italy. piercarlo.braga@unimi.it
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Braga
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Culici
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Dal Sasso
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D017097:Electric Impedance; D004917:Erythromycin / Q000737:chemistry / Q000494:pharmacology; D015644:Miocamycin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000254:growth & development; D013997:Time Factors
D000900:Anti-Bacterial Agents; D015644:Miocamycin; D004917:Erythromycin; C033383:rokitamycin