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Intraphagocytic activity of erythromycin, roxithromycin and azithromycin
1Department of Medical Microbiology, Technical University Munich, FRG.
Summary
Erythromycin and roxithromycin showed bacteriostatic activity against Staphylococcus aureus inside cells. Azithromycin did not prevent bacterial growth and was less effective in acidic conditions.
Area of Science:
- Pharmacology
- Microbiology
- Infectious Diseases
Background:
- Staphylococcus aureus is a common pathogen that can survive within host cells.
- Intracellular activity of antibiotics is crucial for eradicating certain infections.
- Macrolide antibiotics like erythromycin, roxithromycin, and azithromycin are used to treat S. aureus infections.
Purpose of the Study:
- To compare the intraphagocytic activity of erythromycin, roxithromycin, and azithromycin against Staphylococcus aureus.
- To investigate the pH dependency of the antibacterial effects of these macrolides.
Main Methods:
- Comparison of the intraphagocytic activity of erythromycin, roxithromycin, and azithromycin against phagocytosed Staphylococcus aureus.
- Assessment of antibacterial activity at concentrations of 10X Minimum Inhibitory Concentration (MIC).
- Evaluation of the pH dependency of the drugs' antibacterial effects.
Main Results:
- Erythromycin and roxithromycin exhibited bacteriostatic activity against intracellular Staphylococcus aureus at 10X MIC.
- Azithromycin failed to inhibit the intracellular proliferation of Staphylococcus aureus.
- Azithromycin's antibacterial activity was diminished in acidic environments compared to the other two drugs.
Conclusions:
- Erythromycin and roxithromycin possess significant intraphagocytic activity against Staphylococcus aureus.
- Azithromycin's efficacy against intracellular Staphylococcus aureus is limited, particularly in acidic conditions.
- The pH-dependent activity of azithromycin may impact its effectiveness in intracellular infections.