Antibiotic prophylaxis in patients with valvular heart defects undergoing dermatological surgery remains a confusing issue despite apparently clear guidelines.

The guidelines pertaining to prescription of prophylactic antibiotics to prevent endocarditis during dermatological surgery appear clear and well-documented. The British Society for Dermatological Surgery, in agreement with the British Society for Antimicrobial Chemotherapy, state that antibiotic prophylaxis for endocarditis is not required for routine dermatological surgery procedures even in the presence of a pre-existing heart lesion. Pre-existing cardiac lesions include prosthetic valves, history of bacterial endocarditis, congenital cardiac malformation, rheumatic or other acquired valvular dysfunction, hypertrophic cardiomyopathy or mitral valve prolapse with regurgitation. It is important to distinguish between antibiotic prophylaxis for wound infection and that for bacterial endocarditis. Routine procedures, such as punches, shaves, curettage and simple excisions, performed on clean intact skin have an extremely low risk of wound infection (1-4%). The risk of wound infection increases to 5-15% with clean-contaminated skin surgery that includes procedures involving eroded or ulcerated skin, respiratory or buccal mucosa, flexural areas and protracted procedures such as Mohs' micrographic surgery. In such cases, antibiotic prophylaxis may be considered in patients with a cardiac lesion because a wound infection may result in bacteraemia and subsequent endocarditis. This should therefore not be considered 'routine' dermatological surgery. In contaminated, dirty and/or infected classes of wounds the risk of wound infection is higher (> 25%). Elective skin surgery should be postponed if possible until the wound infection is treated with therapeutic antibiotics.