Primary bacterial infection of the myocardium.

Primary bacterial infection of myocardial tissue without associated endocarditis occurs only rarely. It is generally seen in the setting of overwhelming bacteremia. The most common bacterial cause of myocarditis is Staphylococcus aureus, although infections with a broad range of bacterial pathogens have been described. Pathologically, the disease process is characterized by multifocal studding of the myocardium with tiny abscesses, and the left ventricle is most commonly involved. Complications include cardiac dysfunction, rhythm disturbances, and myocardial rupture with secondary purulent pericarditis. Since virtually all information regarding primary bacterial myocarditis originates from autopsy studies conducted in the pre-antibiotic era, little is known about the modern approach to diagnosis and management of this clinical entity.