Auricular Cartilage Infection After Cefalexin Failure
For a painful auricular cartilage infection (perichondritis) that has failed cefalexin, you must immediately switch to an antipseudomonal fluoroquinolone—specifically ciprofloxacin 500-750 mg twice daily orally—because Pseudomonas aeruginosa is the most common pathogen in auricular cartilage infections and cefalexin has zero activity against it.
Why Cefalexin Failed
- Cefalexin has no activity against Pseudomonas aeruginosa, which is the predominant pathogen in auricular cartilage infections, particularly those involving piercing trauma 1
- Cefalexin only covers methicillin-susceptible Staphylococcus aureus (MSSA) and streptococci, making it an inappropriate choice for cartilage infections 2, 1
- The cartilage of the auricle has poor blood supply, and Pseudomonas thrives in this environment, especially after piercing-related trauma 2
Recommended Next Antibiotic
Ciprofloxacin is the treatment of choice:
- Ciprofloxacin 500-750 mg orally twice daily provides excellent coverage against Pseudomonas aeruginosa with high bioavailability 2
- Higher doses (750 mg twice daily) should be used for confirmed or suspected Pseudomonas infections to ensure adequate tissue penetration 2
- Ciprofloxacin demonstrates biofilm activity in vitro and animal models, which is critical for cartilage infections where biofilm formation is common 2
- Treatment duration should be at least 2-3 weeks for cartilage involvement, as these are deep tissue infections requiring prolonged therapy 2
Alternative Options if Fluoroquinolones Contraindicated
If ciprofloxacin cannot be used (pregnancy, children, tendon disorders):
- Combination therapy with an antipseudomonal beta-lactam plus an aminoglycoside may be necessary 3, 4
- Ceftazidime (a third-generation cephalosporin with antipseudomonal activity) could be considered, but requires parenteral administration 4
- Piperacillin-tazobactam provides broad coverage including Pseudomonas but also requires IV administration 2
Critical Management Points
- Obtain wound cultures immediately before switching antibiotics to confirm Pseudomonas and guide definitive therapy 2
- Surgical debridement may be required if there is abscess formation or necrotic cartilage, as antibiotics alone often fail in established cartilage infections 2
- Do not use cephalexin, other first-generation cephalosporins, or any beta-lactam without antipseudomonal activity for auricular cartilage infections 1, 5
- Monitor for treatment failure at 48-72 hours; if no improvement, consider IV therapy with ceftazidime or piperacillin-tazobactam plus an aminoglycoside 3, 4
Common Pitfall to Avoid
The most common error is treating auricular perichondritis like simple cellulitis with anti-staphylococcal agents alone. Cartilage infections require antipseudomonal coverage from the outset, and failure to provide this leads to cartilage necrosis and permanent deformity ("cauliflower ear") 2.