In contrast, Staphylococcus bloodstream infections are frequently acquired in a health care setting where they can enter the bloodstream through procedures that cause breaks in the integrity of skin, such as surgery, catheterization, or during access of long term indwelling catheters or secondary to intravenous injection of recreational drugs.Enterococcus can enter the bloodstream as a consequence of abnormalities in the gastrointestinal or genitourinary tracts.Some organisms, when isolated, give valuable clues to the cause, as they tend to be specific. Pseudomonas species, which are very resilient organisms that thrive in water, may contaminate street drugs that have been contaminated with drinking water. P. aeruginosa can infect a child through foot punctures, and can cause both endocarditis and septic arthritis. S. bovis and Clostridium septicum, which are part of the natural flora of the bowel, are associated with colon cancers. When they present as the causative agent in endocarditis, it usually prompts a colonoscopy to be done immediately due to concerns regarding spread of bacteria from the colon through the bloodstream due to the cancer breaking down the barrier between the inside of the colon (lumen) and the blood vessels which drain the bowel. Less commonly reported bacteria responsible for so called "culture negative endocarditis" include Bartonella, Chlamydia psittaci, and Coxiella. Such bacteria can be identified by serology, culture of the excised valve tissue, sputum, pleural fluid, and emboli, and by polymerase chain reaction or sequencing of bacterial 16S ribosomal RNA.Multiple case reports of infective endocarditis caused by unusual organisms have been published.
Replacement of the valve with a mechanical or bioprosthetic artificial heart valve is necessary in certain situations:
Patients with significant valve stenosis or regurgitation causing heart failure
Evidence of hemodynamic compromise in the form of elevated end-diastolic left ventricular or left atrial pressure or moderate to severe pulmonary hypertension
Presence of intracardiac complications like paravalvular abscess, conduction defects or destructive penetrating lesions
Recurrent septic emboli despite appropriate antibiotic treatment
Large vegetations (> 10 mm)
Persistently positive blood cultures despite appropriate antibiotic treatment
Prosthetic valve dehiscence
Relapsing infection in the presence of a prosthetic valve
Abscess formation
Early closure of mitral valve
Infection caused by fungi or resistant Gram-negative bacteria.The guidelines were recently updated by both the American College of Cardiology and the European Society of Cardiology. There was a recent meta-analysis published that showed surgical intervention at seven days or less is associated with lower mortality. Prognosis
Infective endocarditis is associated with 18% in-hospital mortality. As many as 50% of people with infective endocarditis may experience embolic complications. Epidemiology
In developed countries, the annual incidence of infective endocarditis is 3 to 9 cases per 100,000 persons. Infective endocarditis occurs more often in men than in women. There is an increased incidence of infective endocarditis in persons 65 years of age and older, which is probably because people in this age group have a larger number of risk factors for infective endocarditis. In recent years, over one-third of infective endocarditis cases in the United States was healthcare-associated. Another trend observed in developed countries is that chronic rheumatic heart disease accounts for less than 10% of cases.