From the Guidelines
Macrolides are antibiotics that primarily target gram-positive bacteria, including Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus, as well as atypical pathogens like Mycoplasma pneumoniae, Legionella pneumophila, and Chlamydia species, and some gram-negative bacteria such as Haemophilus influenzae, Moraxella catarrhalis, Bordetella pertussis, and Campylobacter jejuni. The most recent and highest quality study 1 provides evidence that macrolides are effective against a range of bacterial infections, including community-acquired pneumonia. Some key points to consider when using macrolides include:
- Their mechanism of action, which involves binding to the 50S subunit of bacterial ribosomes and inhibiting protein synthesis
- Their effectiveness against atypical pathogens, making them valuable for community-acquired pneumonia treatment
- The potential for resistance, particularly among Streptococcus pneumoniae, which can limit their effectiveness
- The importance of selecting the appropriate macrolide and dose for the specific infection being treated, such as azithromycin 500mg on day one followed by 250mg daily for four more days, or clarithromycin 500mg twice daily for 7-14 days. It's also worth noting that macrolides can be used in combination with other antibiotics, such as beta-lactams, to provide broader coverage and improve outcomes 1. Overall, macrolides are a useful class of antibiotics that can be effective against a range of bacterial infections, but their use should be guided by careful consideration of the potential benefits and limitations, as well as the most recent and highest quality evidence.
From the FDA Drug Label
1 INDICATIONS AND USAGE
1.1 Acute Bacterial Exacerbation of Chronic Bronchitis Clarithromycin extended-release tablets are indicated in adults for the treatment of mild to moderate infections caused by susceptible isolates due to Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis,or Streptococcus pneumoniae
- 2 Acute Maxillary Sinusitis Clarithromycin extended-release tablets (in adults) are indicated for the treatment of mild to moderate infections caused by susceptible isolates due to Haemophilus influenzae, Moraxella catarrhalis,or Streptococcus pneumoniae
- 3 Community-Acquired Pneumonia Clarithromycin extended-release tablets are indicated [see Indications and Usage (1.9)] for the treatment of mild to moderate infections caused by susceptible isolates due to: Haemophilus influenzae(in adults) Haemophilus parainfluenzae(in adults) Moraxella catarrhalis(in adults) Mycoplasma pneumoniae, Streptococcus pneumoniae, Chlamydophila pneumoniae(in adults)
The bacteria covered by macrolides, specifically clarithromycin, include:
- Haemophilus influenzae
- Haemophilus parainfluenzae
- Moraxella catarrhalis
- Streptococcus pneumoniae
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae 2
From the Research
Bacteria Covered by Macrolides
Macrolides are effective against a range of bacteria, including:
- Gram-positive cocci, such as:
- Atypical pathogens, such as:
- Haemophilus influenzae 3, 4, 5, 6, 7
- Moraxella catarrhalis 3, 4, 5, 6
- Chlamydia trachomatis 6
- Helicobacter pylori 6
- Mycobacterium avium complex (MAC) 6
Limitations of Macrolides
Macrolides have limited activity against:
- Gram-negative bacteria, including Enterobacteriaceae and other ESKAPE pathogens 7
- Macrolide-resistant streptococci species, which produce an efflux pump (mef) or have ribosomal target modification (erm) 3
New Developments in Macrolides
Recent studies have led to the discovery of new macrolides with extended-spectrum activity against multi-drug resistant Gram-negative pathogens 7. These new macrolides have been designed to overcome the limitations of traditional macrolides, including their inability to cross the polar Gram-negative outer membrane and their susceptibility to efflux.