Susceptibility of methicillin-resistant Staphylococcus aureus to vancomycin, teicoplanin, linezolid, pristinamycin and other antibiotics

Zmira Samra*, Orit Ofer, Haim Shmuely

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Methicillin-resistant Staphylococcus aureus is a major nosocomial pathogen worldwide. Vancomycin is the traditional drug of choice, but decreasing susceptibility to vancomycin and other glycopeptides has been reported since 1996. Objectives: To test the in vitro activity of linezolid (oxazolidinone) and other antimicrobial agents against MRSA isolates recovered from hospitalized patients. Methods: We tested 150 MRSA isolates recovered from hospitalized patients. The minimal inhibitory concentration of vancomycin, teicoplanin, pristinamycin (quinupristin-dalforistin) and linezolid was determined by the Etest method. Susceptibility to other antibiotics was tested by the disk diffusion method. Results: All isolates were sensitive to vancomycin, teicoplanin, pristinamycin, and linezolid. The MIC90 was 2.0 μg/ml for vancomycin and teicoplanin (range 0.5-2.0 μg/ml and 0.125-2.0 μg/ml, respectively), and 0.5 μg/ml for pristinamycin and linezolid (range 0.125-0.75 μg/ml and 0.125-0.5 μg/ml, respectively). Of the other antibiotics, fusidic acid showed the best in vitro activity, with 96.7% susceptibility, associated with trimethoprim/sulfamethoxazole (85.8%) and minocycline (84%). Penicillin was associated with the lowest susceptibility (1.3%), associated with ofloxacin (3%) and erythromycin (14%). An increase in the minimal inhibitory concentration value of vancomycin was associated with a significant decrease in resistance to TMP-SMZ (P < 0.01) and an apparent increase in resistance to other antibiotics. Conclusion: The excellent in vitro activity of linezolid and its reported in vivo effectiveness renders it an important therapeutic alternative to vancomycin in the treatment of MRSA infection.

Original languageEnglish
Pages (from-to)148-150
Number of pages3
JournalIsrael Medical Association Journal
Volume7
Issue number3
StatePublished - Mar 2005

Keywords

  • Antibiotic resistance
  • Methicillin resistance
  • Staphylococcus aureus

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