If they have been damaged — from rheumatic fever, for example — the risk of bacterial attachment is increased.This classification is now discouraged, because the ascribed associations (in terms of organism and prognosis) were not strong enough to be relied upon clinically.The terms short incubation (meaning less than about six weeks), and long incubation (greater than about six weeks) are preferred.

valve validating rejected-89

As a result, defensive immune system mechanisms (such as white blood cells) cannot directly reach the valves via the bloodstream.

If an organism (such as bacteria) attaches to a valve surface and forms a vegetation, the host's immune response is blunted.

The lack of blood supply to the valves also has implications for treatment, since drugs also have difficulty reaching the infected area.

Normally, blood flows smoothly through these valves.

By far the most common cause of a "culture-negative" endocarditis is prior administration of antibiotics.

Sometimes microorganisms can take a longer period of time to grow in the culture media, such organisms are said to be fastidious because they have demanding growth requirements.

Some examples include pathogens like Aspergillus species, Brucella species, Coxiella burnetii, Chlamydia species, and HACEK bacteria.

It is an inflammation of the inner tissues of the heart, the endocardium, usually of the valves.

It is caused by infectious agents, or pathogens, which are largely bacterial but a few other organisms can also be responsible.