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Comparative in vitro activity of clarithromycin. Spanish Collaborative Group
E Loza1, J Martínez Beltrán, F Baquero
1Ramón y Cajal Hospital, Department of Microbiology, Madrid, Spain.
Summary
Clarithromycin, a new macrolide antibiotic, shows superior in vitro activity against many bacteria compared to erythromycin. It also demonstrates higher intrinsic activity than roxithromycin and miocamycin, with bactericidal effects on certain strains.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Macrolide antibiotics are crucial in treating bacterial infections.
- Emerging macrolides require comparative analysis of their antimicrobial spectrum and potency.
- Understanding antibiotic efficacy against diverse clinical isolates is essential for effective treatment strategies.
Purpose of the Study:
- To compare the in vitro activity of clarithromycin against various bacterial pathogens.
- To evaluate clarithromycin's efficacy relative to other established antibiotics, including erythromycin, roxithromycin, and miocamycin.
- To identify potential cross-resistance patterns within the macrolide class.
Main Methods:
- In vitro antimicrobial susceptibility testing was performed on 3,880 clinical bacterial isolates.
- Comparative analysis of clarithromycin's activity against key Gram-positive and Gram-negative bacteria, atypical pathogens, and specific genera like Staphylococcus, Enterococcus, Streptococcus, Brucella, Legionella, Mycoplasma, Ureaplasma, and Campylobacter.
- Assessment of bactericidal activity against Streptococcus spp. and Haemophilus influenzae.
Main Results:
- Clarithromycin exhibited significantly higher activity than erythromycin against Staphylococcus aureus, Enterococcus species, various Streptococcus groups, Brucella melitensis, Legionella pneumophila, and Mycoplasma spp.
- Clarithromycin demonstrated 16-fold greater activity against Ureaplasma urealyticum but reduced activity against Campylobacter spp.
- Intrinsic activity of clarithromycin was 2-4 times higher than roxithromycin and 4-8 times higher than miocamycin, with observed cross-resistance among macrolides.
Conclusions:
- Clarithromycin presents a potent in vitro antimicrobial profile, exceeding erythromycin against a broad range of clinically relevant bacteria.
- The new macrolide shows favorable comparative activity against roxithromycin and miocamycin, suggesting potential as a valuable therapeutic agent.
- Clarithromycin exhibits bactericidal properties against Streptococcus spp. and Haemophilus influenzae, highlighting its potential in treating specific infections.