What is the recommended prophylactic antibiotic for patients allergic to penicillin with a history of endocarditis?

In patients with a history of endocarditis who are allergic to penicillin, clindamycin is typically recommended as the prophylactic antibiotic. This is because clindamycin is effective against many of the same bacteria that cause endocarditis, particularly Staphylococcus and Streptococcus species.

Clindamycin also has good oral bioavailability, making it a convenient choice for prophylaxis, especially in instances where intravenous administration may not be necessary. Moreover, it is typically well tolerated by patients with penicillin allergies, reducing the risk of allergic reactions.

The other options, while they have their uses, are not the first choice in this context. Cephalexin, for example, is a cephalosporin which may pose a risk for cross-reactivity in patients with a penicillin allergy. Vancomycin, although effective against resistant strains, is usually reserved for situations involving more severe infections or when resistance is a factor. Azithromycin, while it can be used for certain infections, is not the preferred choice for endocarditis prophylaxis. Thus, clindamycin stands out as the appropriate prophylactic antibiotic for this specific patient population.