In vitro selection of resistance to clarithromycin in Streptococcus pneumoniae clinical isolates

L. Drago, E. De Vecchi, L. Nicola, D. Legnani, M. Prenna, S. Ripa

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

In this study the effects of exposure to serum, lung and breakpoint concentrations on Streptococcus pneumoniae susceptibility to clarithromycin, azithromycin, amoxicillin/clavulanate, levofloxacin and moxifloxacin were evaluated. Development of resistance was determined by multi-step and single-step methodologies. In the first experimental set, minimum inhibitory concentrations (MICs) were determined after 10 passages on antibiotic-gradient plates and 10 passages on antibiotic-free plates. Acquisition of resistance was defined as an increase of ≥4-fold from the starting MIC. In single-step studies, the rate of spontaneous mutations was calculated after a passage on antibiotic-containing agar plates. Azithromycin and levofloxacin gave the highest number of strains with MIC increased of at least 4 times the starting value, followed by moxifloxacin and by clarithromycin which only at the lowest concentration tested selected for resistance in 5 strains. Amoxicillin/ clavulanate never displayed ≥4-fold MIC increase. Frequencies of mutation were lower for clarithromycin and moxifloxacin than for the comparators. At lung concentrations clarithromycin had limited potential to select for resistance.

Original languageEnglish
Pages (from-to)161-168
Number of pages8
JournalJournal of Chemotherapy
Volume17
Issue number2
Publication statusPublished - Apr 2005

Fingerprint

Clarithromycin
Microbial Sensitivity Tests
Streptococcus pneumoniae
Clavulanic Acid
Levofloxacin
Azithromycin
Amoxicillin
Mutation Rate
Anti-Bacterial Agents
Lung
Agar
In Vitro Techniques
Serum
moxifloxacin

Keywords

  • Amoxicillin/ clavulanate
  • Azithromycin
  • Clarithromycin
  • Levofloxacin
  • Moxifloxacin
  • Resistance
  • Streptococcus pneumoniae

ASJC Scopus subject areas

  • Pharmacology (medical)
  • Microbiology (medical)

Cite this

In vitro selection of resistance to clarithromycin in Streptococcus pneumoniae clinical isolates. / Drago, L.; De Vecchi, E.; Nicola, L.; Legnani, D.; Prenna, M.; Ripa, S.

In: Journal of Chemotherapy, Vol. 17, No. 2, 04.2005, p. 161-168.

Research output: Contribution to journalArticle

Drago, L. ; De Vecchi, E. ; Nicola, L. ; Legnani, D. ; Prenna, M. ; Ripa, S. / In vitro selection of resistance to clarithromycin in Streptococcus pneumoniae clinical isolates. In: Journal of Chemotherapy. 2005 ; Vol. 17, No. 2. pp. 161-168.
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