PVE is divided into early (within 60 days of valve insertion) and late disease. Early PVE reflects perioperative contamination, either directly or through catheters (especially central lines). Staphylococcal infection accounts for 45-50% of cases, with S. epidermidis the most commonly isolated agent in early PVE (25-30%), followed by S. aureus (20-25%), gram-negative aerobic organisms (20%), and fungi (10-20%). Late PVE reflects seeding of the valve by transient bacteremia, especially from dental, genitourinary, or gastrointestinal manipulation; thus the organisms resemble those in native valve IE, with Streptococcus viridans being the most commonly isolated (25-30%), followed by Staphylococcus epidermidis and S. aureus (25% and 10%, respectively).
Which prosthetic valve is more likely to acquire IE?
The rate of PVE is approximately the same for mechanical and tissue valves, but the aortic valve is 2-5 times more likely to be involved than the mitral valve.
What is the most common cause of culture-negative endocarditis?
The most common cause is inadequate therapy of prior endocarditis; culture-negative IE accounts for 5% of total cases.
What are the HACEK gram-negative organisms?
Haemophilus aphrophilus Actinobacillus actinomycetemcomitans Cardiobacterium hominis Eikenella corrodens Kingella kingae