In vitro interaction between mecillinam and piperacillin-tazobactam in the presence of azithromycin against members of the Enterobacteriaceae family and Pseudomonas aeruginosa

Elisabetta Maioli, Eugenio A. Debbia, Laura Gualco, Anna Marchese

Research output: Contribution to journalArticlepeer-review

Abstract

Mecillinam was tested in vitro alone or in combination with piperacillin-tazobactam and azithromycin against representative species of the Enterobacteriaceae family and Pseudomonas aeruginosa to extend its antibacterial spectrum, and to protect mecillinam from inactivating enzymes taking advantage of the presence of tazobactam. Drug interactions were studied by microdilution method, by selection of spontaneous resistant mutants on agar plates containing the drugs in combination and by time kill experiments. Against Enterobacteriaceae mecillinam and piperacillin-tazobactam showed synergistic interaction in 24/60 tests carried out by microdilution technology, in 4/16 by selecting resistant mutants and in 5/9 by time-kill experiments. P. aeruginosa reacted indifferently to the drug combinations, with few exceptions, when azithromycin was present a reduction of the MICs were recorded. Mecillinam reacted favourably in vitro in combination with piperacillin-tazobactam against not only strains included in its antibacterial spectrum but also against resistant Morganella morganii, Proteus spp and P. aeruginosa. The addition of azithromycin (8 mg/L) was beneficial for the drug combination increasing the bactericidal effect in the great majority of the cases. Only systematic in vivo studies may establish the clinical significance and benefits of the present observations.

Original languageEnglish
Pages (from-to)37-46
Number of pages10
JournalNew Microbiologica
Volume31
Issue number1
Publication statusPublished - Jan 2008

Keywords

  • Azithromycin
  • Enterobacteriaceae
  • In vitro interactions
  • Mecillinam
  • P. aeruginosa
  • Piperacillin-tazobactam
  • Spontaneous-resistant mutants
  • Time-kill

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)

Fingerprint Dive into the research topics of 'In vitro interaction between mecillinam and piperacillin-tazobactam in the presence of azithromycin against members of the Enterobacteriaceae family and Pseudomonas aeruginosa'. Together they form a unique fingerprint.

Cite this