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
- Enteric streptococci
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.