In a patient with a penicillin allergy but no history of anaphylaxis, which antibiotic is appropriate for endocarditis prophylaxis?

In a patient with a penicillin allergy but no history of anaphylaxis, which antibiotic is appropriate for endocarditis prophylaxis?

• A. Clindamycin
• B. Azithromycin
• C. Amoxicillin
• D. Cephalexin

Answer: (D)

In endocarditis prophylaxis for dental procedures, you want an antibiotic that reliably covers the viridans group streptococci and is safe in someone with a penicillin allergy but without a history of anaphylaxis. A first-generation cephalosporin like cephalexin fits this scenario well because its spectrum includes oral streptococci and, since there’s no anaphylaxis history, the cross-reactivity risk with penicillins is considered acceptably low. Therefore cephalexin is an appropriate choice for prophylaxis. Amoxicillin would be inappropriate because it is a penicillin and the patient has a penicillin allergy. Clindamycin is a valid alternative if a cephalosporin cannot be used, but cephalexin is preferred here given the absence of an anaphylactic history. Azithromycin can be used in penicillin-allergic patients as an option, but cephalexin is the more standard first-line alternative in this particular scenario.

In endocarditis prophylaxis for dental procedures, you want an antibiotic that reliably covers the viridans group streptococci and is safe in someone with a penicillin allergy but without a history of anaphylaxis. A first-generation cephalosporin like cephalexin fits this scenario well because its spectrum includes oral streptococci and, since there’s no anaphylaxis history, the cross-reactivity risk with penicillins is considered acceptably low. Therefore cephalexin is an appropriate choice for prophylaxis.

Amoxicillin would be inappropriate because it is a penicillin and the patient has a penicillin allergy. Clindamycin is a valid alternative if a cephalosporin cannot be used, but cephalexin is preferred here given the absence of an anaphylactic history. Azithromycin can be used in penicillin-allergic patients as an option, but cephalexin is the more standard first-line alternative in this particular scenario.