Let’s turn now to the classification. We used to classify infective endocarditis as either
acute endocarditis or sub-acute and sometimes even chronic. But those terms are really outmoded.
We now classify them as either native valve endocarditis which accounts for about 78%.
Among the native valve endocarditis, we include community-acquired and healthcare-associated,
either nosocomial that developed in the hospital or non-nosocomial, that is a patient who’s a frequent flyer
to the hospital, say, a dialysis patient. Then there’s another form of native valve endocarditis
called that due to IV drug use and you can see the percentages. Also, we talk about pacemaker
and defibrillator related endocarditis of native valves. Then we turn to the other classification
which is prosthetic valve endocarditis and this includes early - less than 2 months,
midterm - 2 to 12 months, and late - greater than 12 months. Why do we classify them
like that, early, mid-term, and late? Well, as you might expect, if somebody develops infection
on a prosthetic heart valve shortly after surgery, it’s very likely due to the organisms that were either
in the hospital at the time the surgery was done before the wound healed or from skin bugs
that fell into the healing wound, into the open wound or into the healing wound.
Mid-term still includes some of those organisms but other organisms begin to creep in.
Late prosthetic valve endocarditis, think about more than 12 months, the endothelium has covered
that valve, so it’s got a new surface at that point. So actually, late prosthetic valve endocarditis
is going to act a lot more like native valve endocarditis.
Infective Endocarditis can also be classified into Left side endocardities, affecting the mitral and aortic valves,
and to right side endocardities, affecting the tricuspid and pulmonic valves.
Right side IE is common in IVDU.