Suprax Coverage for H. influenzae and Drug-Resistant Pneumococcus
Suprax (cefixime) provides excellent coverage for H. influenzae, including beta-lactamase-producing strains, but has poor activity against S. pneumoniae and should NOT be used when drug-resistant pneumococcus is a concern. 1
Coverage Against H. influenzae
Cefixime demonstrates potent activity against H. influenzae:
- Inhibits 90% of H. influenzae strains (both beta-lactamase producers and non-producers) at concentrations less than 0.25 mg/L 2
- Maintains excellent activity against beta-lactamase-producing strains, which account for approximately 50% of H. influenzae in most geographic areas 1
- Not destroyed by plasmid-mediated beta-lactamases (TEM and ROB types) produced by Haemophilus species 2
- FDA-approved for otitis media caused by H. influenzae 3
Coverage Against Drug-Resistant S. pneumoniae
Cefixime has inadequate activity against S. pneumoniae and is especially ineffective against penicillin-resistant strains:
- Both cefixime and ceftibuten have poor activity against S. pneumoniae and are especially ineffective against penicillin-resistant strains 1
- Neither of these drugs should be used for acute bacterial sinusitis where pneumococcus is a concern 1
- Has no clinically significant activity against drug-resistant S. pneumoniae (DRSP) 1
- May occasionally fail against even penicillin-susceptible pneumococci 1
- Clinical trials showed approximately 10% lower overall response rates for S. pneumoniae compared to control drugs in otitis media 3
Clinical Implications
When pneumococcal coverage is needed, alternative agents should be selected:
- Preferred alternatives for DRSP coverage: High-dose amoxicillin (90 mg/kg/day), amoxicillin-clavulanate (90 mg/6.4 mg/kg/day), cefpodoxime, cefdinir, or respiratory fluoroquinolones 1
- Cefixime maintains bactericidal activity against H. influenzae and M. catarrhalis but does not maintain bactericidal activity against S. pneumoniae 4
- For infections where both pathogens are possible (e.g., community-acquired pneumonia, sinusitis), cefixime is inappropriate as monotherapy 1
Common Pitfall to Avoid
The major clinical error is using cefixime for respiratory tract infections where S. pneumoniae is a likely pathogen, particularly in areas with high rates of penicillin resistance (25-50% of strains) 1. While cefixime's excellent H. influenzae coverage may seem attractive, the poor pneumococcal activity makes it unsuitable for empiric therapy in most respiratory infections where both organisms are common pathogens.