Effectiveness of Macrolides in CAP

Current Guidelines:

• NAG 2014: any oral macrolides for CAP with comorbidities or antibiotic use within 3 months
• BTS 2009 : Amoxycillin / Doxycycline
• IDSA/ITS : Macrolides / Doxycycline

Comparison between Macrolides
Spectrum

• active against gram-positive cocci (mainly staphylococci and streptococci) and bacilli, and to lesser-extent gram-negative cocci
• With the exception of Bordetella pertussis, Campylobacter, Chlamydia, Helicobacter, and Legionella species, gram-negative bacilli are generally resistant to the macrolides
• clarithromycin is superior to that of erythromycin and azithromycin in terms of gram-positive activity of, especially against Streptococcus pyogenes and Streptococcus pneumoniae
• Azithromycin is more active than clarithromycin against H. influenzae
• Despite the improvements clarithromycin and azithromycin offer, both these agents demonstrate cross-resistance with erythromycin

Pharmacologic

• bioavailability of clarithromycin is more than twice that of erythromycin, and the bioavailability of azithromycin is 1.5 times that of erythromycin
• Azithromycin has been shown to penetrate tissues rapidly and extensively.
• Its levels in pulmonary macrophages, polymorphonuclear leukocytes, tonsillar tissue, and genital or pelvic tissue remain increased for extended periods, with a mean tissue half-life of 2 to 4 days

Side Effects

• Newer macrolides clarithromycin and azithromycin cause significantly less gastrointestinal side effects (nausea, vomiting, abdominal discomfort, and diarrhea) than erythromycin
• Azithromycin and roxithromycin are less potent at provoking arrhythmia than clarithromycin and erythromycin

References:

1. http://www.emedexpert.com/compare/macrolides.shtml
2. http://www.annalsofintensivecare.com/content/1/1/48
3. Second Meeting of the Subcommittee of the Expert Committee on the Selection and Use of Essential Medicines Geneva, 29 September to 3 October 2008
4. www.uptodate.com
5. Antibiotics for community-acquired pneumonia in children (Review). Cochrane
6. http://www.aafp.org/afp/2004/0401/p1699.html