A nurse is caring for a client who has cellulitis and is to begin antibiotic therapy. The client has a history of anaphylactic reaction to penicillin. Which of the following medications is contraindicated for this client?

A. Fluconazole. Fluconazole is an antifungal medication used to treat fungal infections, such as candidiasis. It is not related to penicillin and does not pose a risk for cross-reactivity in clients with a penicillin allergy. It can be safely administered in this scenario. B. Tetracycline. Tetracycline is a broad-spectrum antibiotic used to treat bacterial infections, including acne and respiratory infections. It belongs to a different antibiotic class than penicillins and cephalosporins, meaning it does not pose a risk of cross-reactivity in clients with a penicillin allergy. C. Acyclovir. Acyclovir is an antiviral medication used to treat viral infections, such as herpes simplex and varicella-zoster. Since it does not belong to the beta-lactam antibiotic class, it is not contraindicated for clients with a penicillin allergy. D. Cephalexin. Cephalexin is a first-generation cephalosporin, which shares a similar beta-lactam ring structure with penicillins. Clients with a history of an anaphylactic reaction to penicillin are at increased risk of cross-reactivity with cephalosporins, particularly first-generation ones like cephalexin. Due to the severity of the client’s allergic reaction, cephalexin should be avoided, and an alternative non-beta-lactam antibiotic should be considered.