Test Your Knowledge Answer #454

Given the extent of cellulitis surrounding the ulcer, the presence of lymphangitis, and the systemic signs of illness (i.e., fever and elevated leukocyte count), this patient has a severe diabetic foot ulcer. The bacteriology of such infections suggests the need for broad-spectrum antibiotic coverage, including regimens that cover not only gram-positive cocci, such as staphylococcus, but also gram-negative rods (and possibly anaerobes). Piperacillin-tazobactam and imipenem are excellent choices, with a good safety profile and very broad-spectrum activity. Vancomycin, linezolid, and daptomycin are also good choices, but only if gram-negative coverage with drugs such as ceftazidime or ciprofloxacin is also added; anaerobic coverage may or may not be added. Vancomycin alone is not sufficient because it covers only gram-positive bacteria. Clindamycin plus gentamicin is not the best choice because of concerns of nephrotoxicity. Trimethoprim-sulfamethoxazole should be reserved for mild infections.