In vitro induction of resistance by tissue concentrations of azithromycin, clarithromycin, cefixime and amoxicillin/clavulanate in clinical isolates of Streptococcus pyogenes

E. De Vecchi, L. Nicola, E. Zucchetti, L. Drago

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

This study evaluated the effects of exposure to serum, tonsils and breakpoint drug concentrations of clarithromycin, azithromycin, cefixime and amoxicillin/clavulanate on Streptococcus pyogenes susceptibility. Frequency of mutation and development of resistance after ten passages on antibiotic gradient plates, followed by ten passages without antibiotic, were determined. Phenotypes of macrolide-resistant strains grown at the end of multi-step selection were also determined. Azithromycin induced a surge of resistant strains more rapidly and frequently than clarithromycin, particularly at tonsils concentrations. With amoxicillin/clavulanate no strains showed minimum inhibitory concentrations (MICs) higher than the susceptibility breakpoint. Mutational frequencies were higher for azithromycin, at serum and breakpoint drug concentrations, than for the other drugs. Most of the macrolide resistant strains showed an MLSB phenotype. In conclusion, the ability to prevent the occurrence of resistance in clinical isolates of S. pyogenes was similar for amoxicillin/clavulanate and clarithromycin followed by cefixime > azithromycin when tonsil drug concentrations were considered, and greater for amoxicillin/clavulanate followed by clarithromycin > cefixime> azithromycin, at breakpoint and serum concentrations.

Original languageEnglish
Pages (from-to)379-388
Number of pages10
JournalJournal of Chemotherapy
Volume18
Issue number4
Publication statusPublished - Aug 2006

Fingerprint

Cefixime
Clavulanic Acid
Azithromycin
Clarithromycin
Streptococcus pyogenes
Amoxicillin
Palatine Tonsil
Macrolides
Pharmaceutical Preparations
Serum
Anti-Bacterial Agents
Phenotype
Microbial Sensitivity Tests
Mutation Rate
In Vitro Techniques

Keywords

  • Amoxicillin/clavulanate
  • Azithromycin
  • Cefixime
  • Clarithromycin
  • In vitro selection of resistance
  • Streptococcus pyogenes

ASJC Scopus subject areas

  • Pharmacology (medical)
  • Microbiology (medical)

Cite this

@article{49efae0053394ee79f249878aef11f12,
title = "In vitro induction of resistance by tissue concentrations of azithromycin, clarithromycin, cefixime and amoxicillin/clavulanate in clinical isolates of Streptococcus pyogenes",
abstract = "This study evaluated the effects of exposure to serum, tonsils and breakpoint drug concentrations of clarithromycin, azithromycin, cefixime and amoxicillin/clavulanate on Streptococcus pyogenes susceptibility. Frequency of mutation and development of resistance after ten passages on antibiotic gradient plates, followed by ten passages without antibiotic, were determined. Phenotypes of macrolide-resistant strains grown at the end of multi-step selection were also determined. Azithromycin induced a surge of resistant strains more rapidly and frequently than clarithromycin, particularly at tonsils concentrations. With amoxicillin/clavulanate no strains showed minimum inhibitory concentrations (MICs) higher than the susceptibility breakpoint. Mutational frequencies were higher for azithromycin, at serum and breakpoint drug concentrations, than for the other drugs. Most of the macrolide resistant strains showed an MLSB phenotype. In conclusion, the ability to prevent the occurrence of resistance in clinical isolates of S. pyogenes was similar for amoxicillin/clavulanate and clarithromycin followed by cefixime > azithromycin when tonsil drug concentrations were considered, and greater for amoxicillin/clavulanate followed by clarithromycin > cefixime> azithromycin, at breakpoint and serum concentrations.",
keywords = "Amoxicillin/clavulanate, Azithromycin, Cefixime, Clarithromycin, In vitro selection of resistance, Streptococcus pyogenes",
author = "{De Vecchi}, E. and L. Nicola and E. Zucchetti and L. Drago",
year = "2006",
month = "8",
language = "English",
volume = "18",
pages = "379--388",
journal = "Journal of Chemotherapy",
issn = "1120-009X",
publisher = "Maney Publishing",
number = "4",

}

TY - JOUR

T1 - In vitro induction of resistance by tissue concentrations of azithromycin, clarithromycin, cefixime and amoxicillin/clavulanate in clinical isolates of Streptococcus pyogenes

AU - De Vecchi, E.

AU - Nicola, L.

AU - Zucchetti, E.

AU - Drago, L.

PY - 2006/8

Y1 - 2006/8

N2 - This study evaluated the effects of exposure to serum, tonsils and breakpoint drug concentrations of clarithromycin, azithromycin, cefixime and amoxicillin/clavulanate on Streptococcus pyogenes susceptibility. Frequency of mutation and development of resistance after ten passages on antibiotic gradient plates, followed by ten passages without antibiotic, were determined. Phenotypes of macrolide-resistant strains grown at the end of multi-step selection were also determined. Azithromycin induced a surge of resistant strains more rapidly and frequently than clarithromycin, particularly at tonsils concentrations. With amoxicillin/clavulanate no strains showed minimum inhibitory concentrations (MICs) higher than the susceptibility breakpoint. Mutational frequencies were higher for azithromycin, at serum and breakpoint drug concentrations, than for the other drugs. Most of the macrolide resistant strains showed an MLSB phenotype. In conclusion, the ability to prevent the occurrence of resistance in clinical isolates of S. pyogenes was similar for amoxicillin/clavulanate and clarithromycin followed by cefixime > azithromycin when tonsil drug concentrations were considered, and greater for amoxicillin/clavulanate followed by clarithromycin > cefixime> azithromycin, at breakpoint and serum concentrations.

AB - This study evaluated the effects of exposure to serum, tonsils and breakpoint drug concentrations of clarithromycin, azithromycin, cefixime and amoxicillin/clavulanate on Streptococcus pyogenes susceptibility. Frequency of mutation and development of resistance after ten passages on antibiotic gradient plates, followed by ten passages without antibiotic, were determined. Phenotypes of macrolide-resistant strains grown at the end of multi-step selection were also determined. Azithromycin induced a surge of resistant strains more rapidly and frequently than clarithromycin, particularly at tonsils concentrations. With amoxicillin/clavulanate no strains showed minimum inhibitory concentrations (MICs) higher than the susceptibility breakpoint. Mutational frequencies were higher for azithromycin, at serum and breakpoint drug concentrations, than for the other drugs. Most of the macrolide resistant strains showed an MLSB phenotype. In conclusion, the ability to prevent the occurrence of resistance in clinical isolates of S. pyogenes was similar for amoxicillin/clavulanate and clarithromycin followed by cefixime > azithromycin when tonsil drug concentrations were considered, and greater for amoxicillin/clavulanate followed by clarithromycin > cefixime> azithromycin, at breakpoint and serum concentrations.

KW - Amoxicillin/clavulanate

KW - Azithromycin

KW - Cefixime

KW - Clarithromycin

KW - In vitro selection of resistance

KW - Streptococcus pyogenes

UR - http://www.scopus.com/inward/record.url?scp=33749027188&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33749027188&partnerID=8YFLogxK

M3 - Article

C2 - 17024793

AN - SCOPUS:33749027188

VL - 18

SP - 379

EP - 388

JO - Journal of Chemotherapy

JF - Journal of Chemotherapy

SN - 1120-009X

IS - 4

ER -