Lack of in vitro and in vivo selection of bacterial resistance by roxithromycin

Lorenzo Drago, Maria Cristina Fassina, Elena De Vecchi, Barbara Mombelli, Alessandra Lombardi, Maria Rita Gismondo

Research output: Contribution to journalArticlepeer-review


The in vitro and in vivo selective pressure exerted by roxithromycin on Lancefield group A β-haemolytic streptococci (GABHS) was investigated. In vitro antimicrobial activity on fifty GABHS strains was determined by the microdilution method and by boundary concentration (BC) determination. Insorgence of resistance was evaluated by redetermining MIC and BC after exposure to 16 x MIC roxithromycin concentration. In vivo insorgence of resistance was evaluated by MIC and BC determinations on the GABHS strain recovered from infected mice peritoneum, after treatment with 20 mg/kg roxithromycin, The roxithromycin serum kinetics was established in healthy and infected mice. Neither significant changes in GABHS MIC or BC after in vitro or in vivo exposure to roxithromycin nor a difference in roxithromycin serum levels between healthy and infected mice were detected, suggesting that the roxithromycin selection of resistance in GABHS is low. Copyright (C) 2000 S. Karger AG, Basel.

Original languageEnglish
Pages (from-to)160-165
Number of pages6
Issue number3
Publication statusPublished - 2000


  • Macrolide
  • Microbial resistance
  • Roxithromycin
  • Streptococcus

ASJC Scopus subject areas

  • Pharmacology (medical)


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