Is Cephalexin Indicated for Otitis Media?
Cephalexin is FDA-approved for otitis media but is NOT recommended as first-line therapy and should be avoided when Haemophilus influenzae is suspected, as it demonstrates poor clinical efficacy against this pathogen despite in vitro susceptibility. 1, 2
First-Line Treatment Recommendations
Amoxicillin or amoxicillin-clavulanate are the preferred first-line agents for acute otitis media in both children and adults, not cephalexin or other first-generation cephalosporins. 3, 4
Amoxicillin-clavulanate provides superior coverage against beta-lactamase-producing organisms (H. influenzae and M. catarrhalis), which account for 38-62% of treatment failures with plain amoxicillin. 5, 3
Composite susceptibility rates to amoxicillin alone range only 62-89% across the three main pathogens (S. pneumoniae, H. influenzae, M. catarrhalis), making beta-lactamase coverage increasingly important. 5
Why Cephalexin Performs Poorly
A randomized controlled trial demonstrated that 50% of children with H. influenzae otitis media treated with cephalexin had poor clinical responses, compared to 0% treatment failures with ampicillin, despite in vitro susceptibility. 2
This clinical-microbiological disconnect occurs because cephalexin achieves inadequate middle ear fluid concentrations against H. influenzae, even when the organism tests "sensitive" in the laboratory. 2
H. influenzae accounts for 27-33% of acute otitis media cases, making this a clinically significant limitation. 6, 7
FDA-Approved Dosing (When Used)
The FDA label specifies that for otitis media, cephalexin requires 75-100 mg/kg/day in 4 divided doses (higher than standard dosing for other indications). 1
This higher dosing requirement reflects the drug's marginal efficacy for this indication. 1
When Cephalosporins Are Appropriate
Second- and third-generation cephalosporins (cefdinir, cefpodoxime, cefuroxime) are acceptable alternatives for patients with non-severe penicillin allergies or recent antibiotic exposure. 4
These newer cephalosporins demonstrate 83-88% clinical efficacy and provide better H. influenzae coverage than cephalexin. 4
Cefaclor (a second-generation cephalosporin) achieved 97% bacteriologic cure rates in otitis media, including against H. influenzae, demonstrating the superiority of later-generation agents. 8
Critical Clinical Pitfalls
Do not use cephalexin as first-line therapy when amoxicillin or amoxicillin-clavulanate are available, as this increases treatment failure risk and contributes to antibiotic resistance. 4, 2
The only scenario where cephalexin might be considered is for S. aureus otitis media resistant to penicillin, which is exceedingly rare. 2
If a cephalosporin is needed, choose a second- or third-generation agent (cefdinir 300 mg twice daily, cefpodoxime 200 mg twice daily, or cefuroxime 500 mg twice daily for adults) rather than cephalexin. 4, 9