Subacute bacterial endocarditis, abbreviated SBE, is a type of

endocarditis Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves. Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, o ...

(more specifically,

infective endocarditis Infective endocarditis is an infection of the inner surface of the heart (endocardium), usually the heart valve, valves. Signs and symptoms may include fever, petechia, small areas of bleeding into the skin, heart murmur, feeling tired, and anem ...

). Subacute bacterial endocarditis can be considered a form of

type III hypersensitivity Type III hypersensitivity, in the Gell and Coombs classification of allergic reactions, occurs when there is accumulation of immune complexes (antigen-antibody complexes) that have not been adequately cleared by innate immune cells, giving ris ...

Signs and symptoms

Among the signs of subacute bacterial endocarditis are: *

Malaise In medicine, malaise is a feeling of general discomfort, uneasiness or lack of wellbeing and often the first sign of an infection or other disease. It is considered a vague termdescribing the state of simply not feeling well. The word has exist ...

Weakness Weakness is a symptom of many different medical conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, ...

* Excessive

sweat Perspiration, also known as sweat, is the fluid secreted by sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and Apocrine sweat gland, apocrine glands. The eccrine sweat glands are distribu ...

Fever Fever or pyrexia in humans is a symptom of an anti-infection defense mechanism that appears with Human body temperature, body temperature exceeding the normal range caused by an increase in the body's temperature Human body temperature#Fever, s ...

Causes

It is usually caused by a form of Viridans group streptococcus bacteria that normally live in the mouth (''

Streptococcus mutans ''Streptococcus mutans'' is a Facultative anaerobic organism, facultatively anaerobic, gram-positive coccus (round bacteria, bacterium) commonly found in the human oral cavity and is a significant contributor to dental caries, tooth decay. The m ...

, mitis, sanguis ''or ''milleri''). Other strains of streptococci can cause

subacute In medicine, describing a disease as acute denotation, denotes that it is of recent wikt:onset#Noun, onset; it occasionally denotes a short wikt:duration#Noun, duration. The quantification (science), quantification of how much time constitutes "sho ...

endocarditis as well. These include streptococcus intermedius, which can cause acute or subacute infection (about 15% of cases pertaining to infective endocarditis). Enterococci from urinary tract infections and coagulase negative staphylococci can also be causative agents.

Mechanism

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. Underlying structural

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or Slurry, slurries) by opening, closing, or partially obstructing various passageways. Valves are technically Pip ...

disease is usually present in patients before developing subacute endocarditis, and is less likely to lead to septic

emboli An embolism is the lodging of an embolus, a blockage-causing piece of material, inside a blood vessel. The embolus may be a blood clot (thrombus), a fat globule (fat embolism), a bubble of air or other gas ( gas embolism), amniotic fluid (amnio ...

than is acute endocarditis, but subacute endocarditis has a relatively slow process of

infection An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...

and, if left untreated, can worsen for up to one year before it is fatal. In cases of subacute bacterial endocarditis, the causative organism (streptococcus viridans) needs previous heart valve disease to colonize. On the other hand, in cases of acute bacterial endocarditis the organism can colonize on the healthy heart valve, causing the disease.

Diagnosis

Subacute bacterial endocarditis can be diagnosed by collecting three blood culture specimens over a 24-hour period for analysis, also it can usually be indicated by the existence of: * Osler's nodes * Roth's spots *

Nail clubbing Nail clubbing, also known as digital clubbing or clubbing, is a deformity of the finger or toe Nail (anatomy), nails associated with a number of diseases, anomalies and defects, some congenital, mostly of the heart disease, heart and lung disea ...

Treatment

The standard treatment is with a minimum of four weeks of high-dose intravenous

penicillin Penicillins (P, PCN or PEN) are a group of beta-lactam antibiotic, β-lactam antibiotics originally obtained from ''Penicillium'' Mold (fungus), moulds, principally ''Penicillium chrysogenum, P. chrysogenum'' and ''Penicillium rubens, P. ru ...

with an

aminoglycoside Aminoglycoside is a medicinal and bacteriologic category of traditional Gram-negative antibacterial medications that inhibit protein synthesis and contain as a portion of the molecule an amino-modified glycoside (sugar). The term can also refer ...

such as

gentamicin Gentamicin is an aminoglycoside antibiotic used to treat several types of bacterial infections. This may include bone infections, endocarditis, pelvic inflammatory disease, meningitis, pneumonia, urinary tract infections, and sepsis amo ...

. The use of high-dose antibiotics is largely based upon animal models. Leo Loewe of Brooklyn 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.

Signs and symptoms

Causes

Mechanism

Diagnosis

Treatment

See also

References

Further references

External links