| Subacute bacterial endocarditis | |
|---|---|
| Other names | Endocarditis lenta |
 | |
| Vegetation of tricuspid valve by ECHO | |
| Specialty | Cardiology  |
| Symptoms | Malaise, weakness[1] |
| Causes | Streptococcus mutans, mitis, sanguis or milleri bacteria[2][3] |
| Diagnostic method | Blood culture specimens over 24-hour period/analysis[4] |
| Treatment | Intravenous penicillin[2] |
Subacute bacterial endocarditis, abbreviated SBE, is a type ofendocarditis (more specifically,infective endocarditis).[5] Subacute bacterial endocarditis can be considered a form oftype III hypersensitivity.[6]
Among the signs of subacute bacterial endocarditis are:[1]
It is usually caused by a form ofViridans group streptococcus bacteria that normally live in the mouth[3] (Streptococcus mutans, mitis, sanguisormilleri).[2]
Other strains of streptococci can causesubacute endocarditis as well. These includestreptococcus intermedius, which can causeacute or subacute infection (about 15% of cases pertaining to infective endocarditis).[7]
Enterococci from urinary tract infections andcoagulase negative staphylococci can also be causative agents.[5]
The mechanism of subacute bacterial endocarditis could be due to malformed stenotic valves which, in the company of bacteremia, become infected via adhesion and subsequent colonization of the surface area. This causes an inflammatory response, with recruitment of matrix metalloproteinases and destruction of collagen.[8]
Underlying structuralvalve disease is usually present in patients before developing subacute endocarditis, and is less likely to lead tosepticemboli than isacute endocarditis, but subacute endocarditis has a relatively slow process ofinfection and, if left untreated, can worsen for up to one year before it is fatal.[medical citation needed] In cases of subacute bacterial endocarditis, the causative organism (streptococcus viridans) needs previous heart valve disease to colonize.[9] On the other hand, in cases of acute bacterial endocarditis the organism can colonize on the healthy heart valve, causing the disease.[10]
Subacute bacterial endocarditis can be diagnosed by collecting three blood culture specimens over a 24-hour period for analysis,[4] also it can usually be indicated by the existence of:
The standard treatment is with a minimum of four weeks of high-dose intravenouspenicillin with anaminoglycoside such asgentamicin.The use of high-dose antibiotics is largely based upon animal models.[2]
Leo Loewe ofBrooklyn Jewish Hospital was the first to successfully treat subacute bacterial endocarditis with penicillin. Loewe reported at the time seven cases of subacute bacterial endocarditis in 1944.[14]
