Heart Infection: Definitions and Types Infective endocarditis is the microbial invasion of the heart’s inner lining and valves, primarily caused by bacteria such as Staphylococcus aureus, Streptococcus groups, Haemophilus, Pneumococcus, and Pseudomonas. It presents in two distinct forms where acute infection occurs on normal valves by highly virulent bacteria and subacute infection affects already damaged valves through less aggressive organisms. The condition is defined by its involvement of both the endocardium and the heart valves.
Pathogenesis via Endothelial Injury and Bacterial Colonization Turbulent blood flow from valvular disease or intravenous catheter use damages the endocardium, leading to platelet-fibrin deposition on the injured surface. This thrombus provides a platform for bacteria, introduced during transient bacteremia such as that from brushing teeth, to adhere and colonize. The bacteria multiply and form vegetations that eventually seed into the bloodstream, perpetuating the infection.
Clinical Manifestations, Diagnosis, and Management Symptoms include fever, chills, splenomegaly, clubbing, arterial emboli, and distinctive signs like Janeway lesions and Osler nodes, often accompanied by a new or worsened heart murmur. Diagnosis is established through the modified Duke's criteria, requiring positive blood cultures and diagnostic imaging along with specific minor factors. Treatment is tailored to the organism’s sensitivity, using agents such as nafcillin, vancomycin, or appropriate antibiotics for streptococcal infections, while prevention focuses on antisepsis during cardiac and dental interventions.