Polymicrobial infective endocarditis in the 1980s.

Clinical experience over the past decade suggests that the number of cases of polymicrobial infective endocarditis has greatly increased. We found 101 reports of cases of polymicrobial endocardial infection in a review of the English-language literature published in the 1980s. The mean patient age, 36.5 years, reflected a relatively young population, with men outnumbering women almost 2:1. Seventy-one patients were intravenous drug users; only three described recent invasive medical procedures. More than one-half of the patients had infections of the tricuspid valve, and 31 patients developed septic pulmonary emboli. The mean age of patients who died was significantly (P = .004) greater than that of those who survived. In comparison with patients who were infected with three or more organisms, those who were infected with two pathogens were almost twice (38.3% vs. 20.8%) as likely to die of their infections. These differences in mortality reflected the relative paucity of endocardial infections involving the left heart in patients with polymicrobial infections caused by three or more organisms (compared with those infected with two pathogens, P = .0032) and the variability in virulence among infecting agents.