In this episode, I’ll discuss what antibiotic to use in a patient with severe appendicitis and severe penicillin allergy.
In severe appendicitis, antibiotic coverage is typically broadened to cover:
- Pseudomonas aeruginosa
- Enterobacteriaceae
- Enteric streptococci
- Anaerobes
A carbapenem such as meropenem is the usual choice of therapy to cover all of the above pathogens.
Conveniently, the risk of cross-allergenicity between a carbapenem and a penicillin allergy is less than 1% and therefore first line therapy for patients with and without severe penicillin allergy is the same.
If the <1% risk of cross-allergenicity is considered too high, tigecycline alone (although this misses pseudomonas coverage) or the combination of vancomycin + aztreonam + metronidazole may be used. Combining 3 antibiotics may seem excessive but I prefer this combination over tigecycline due to tigecycline’s apparent increase in all-cause mortality compared to other antibiotics.
To download a copy of my free visual critical care antibiotic coverage guide, go to pharmacyjoe.com/abx.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.
Wow carbepenems for appendicitis. We would never go that broad out of the gate. What about piperacillin tazobactam? It is are listed in the guidelines?
Hi Lyle, the context is severe appendicitis and severe penicillin allergy, so piperacillin-tazobactam would unfortunately not be an option.