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In vitro activity of fosfomycin against 'problem' gram-positive cocci

J M Hamilton-Miller1

  • 1Department of Medical Microbiology, Royal Free Hospital School of Medicine, University of London, Great Britain.

Microbios
|January 1, 1992
PubMed

Insights

Fosfomycin shows promise against difficult Gram-positive bacteria, especially under anaerobic conditions. Combinations with rifampicin or ciprofloxacin prevent resistance and demonstrate synergy, suggesting a valuable role for fosfomycin in treating resistant infections.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Pharmacology

Background:

  • Rising antibiotic resistance poses a significant threat to public health.
  • Gram-positive cocci, including methicillin-resistant Staphylococcus aureus (MRSA) and enterococci, are major causes of challenging infections.
  • Limited treatment options are available for infections caused by these resistant pathogens.

Purpose of the Study:

  • To evaluate the in vitro activity of fosfomycin against problematic Gram-positive cocci.
  • To investigate the effect of anaerobic conditions on fosfomycin activity.
  • To assess the potential of combination therapies involving fosfomycin to overcome resistance.

Main Methods:

  • In vitro susceptibility testing of fosfomycin against a panel of Gram-positive cocci.
  • Testing was performed under both aerobic and anaerobic conditions.
  • Checkerboard assays were used to evaluate synergistic effects of fosfomycin in combination with rifampicin or ciprofloxacin.

Main Results:

  • Fosfomycin demonstrated in vitro activity against 54 of 60 Gram-positive isolates, including MRSA, coagulase-negative staphylococci, and enterococci.
  • Activity was enhanced under anaerobic conditions, particularly against coagulase-negative staphylococci.
  • Rifampicin and ciprofloxacin effectively prevented the emergence of fosfomycin-resistant mutants, and synergistic activity was observed in combination therapies.

Conclusions:

  • Fosfomycin exhibits significant in vitro activity against key Gram-positive pathogens.
  • Combination therapy with rifampicin or ciprofloxacin represents a promising strategy to enhance efficacy and prevent resistance.
  • Fosfomycin, when used in appropriate combinations, could be a valuable addition to the armamentarium against difficult-to-treat Gram-positive cocci infections.

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