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, or the ...

(more specifically,

infective endocarditis Infective endocarditis is an infection of the inner surface of the heart, usually the valves. Signs and symptoms may include fever, small areas of bleeding into the skin, heart murmur, feeling tired, and low red blood cell count. Complications ...

). 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 rise ...

Signs and symptoms

Among the signs of subacute bacterial endocarditis are: * Malaise *

Weakness Weakness is a symptom of a number of different 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, i ...

* Excessive

sweat Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distrib ...

Fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...

Causes

It is usually caused by a form of Viridans group streptococcus bacteria that normally live in the mouth ('' Streptococcus mutans, mitis, sanguis ''or ''milleri''). Other strains of streptococci can cause subacute endocarditis as well. These include streptococcus intermedius, which can cause acute or subacute infection (about 15% of cases pertaining to infective endocarditis).

Enterococci ''Enterococcus'' is a large genus of lactic acid bacteria of the phylum Bacillota. Enterococci are gram-positive cocci that often occur in pairs (diplococci) or short chains, and are difficult to distinguish from streptococci on physical charac ...

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 slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fitting ...

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 ( amni ...

than is

acute Acute may refer to: Science and technology * Acute angle ** Acute triangle ** Acute, a leaf shape in the glossary of leaf morphology * Acute (medicine), a disease that it is of short duration and of recent onset. ** Acute toxicity, the adverse eff ...

endocarditis, but subacute endocarditis has a relatively slow process of

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...

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 a 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

Diagnosis of subacute bacterial endocarditis can be done 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 spot Roth's spots, also known as Litten spots or the Litten sign, are non-specific red spots with white or pale centres, seen on the retina and although traditionally associated with infective endocarditis, can occur in a number of other conditions inc ...

s *

Nail clubbing Nail clubbing, also known as digital clubbing or clubbing, is a deformity of the finger or toe nails associated with a number of diseases, mostly of the heart and lungs.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. ...

Treatment

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