Endocarditis From Serratia marcescens

Despite the increasing frequency of nosocomial infections due to nonpigmented strains ofSerratia marcescens, infective endocarditis from this organism is rare. This communication adds three such cases to the previously reported four. Five of the seven patients succumbed to infection. Some predisposing factor could be identified in all seven. Therapy was extremely difficult because of resistance to antibiotics and persistence of infection despite the use of appropriate chemotherapeutic agents, including nalidixic acid intravenously, used unsuccessfully in two patients. The difficulty in eradicating this infection once it has become established on a prosthetic valve is evident. The possibility that intravenous foreign bodies are a source of infection must be considered.