[Antibiotic therapy in infectious endocarditis].

The most common causes of infective endocarditis, accounting for 65 to 85% of all cases, are viridans streptococci and other nonhemolytic streptococci. Enterococci are the offending microorganisms in 5 to 15%, staphylococci in 5 to 15% and gram-negative bacteria from the intestinal tract in 2 to 6%. In rare cases, infective endocarditis may be caused by any of a number of other pathogenic and nonpathogenic bacteria. Men over 60 years of age and women under 40 have a higher likelihood of contracting enterococcal endocarditis subsequent to febrile infections of the urogenital tract or after abortion; intravenous drug users tend to infections with gram-negative bacteria; patients with intravascular catheters who are administered cortisone, broad-spectrum antibiotics or cytostatic drugs are at risk of endocarditis from Candida or Aspergillus. At least two, but in general, five blood cultures should be drawn in short intervals. With the use of proper techniques for detection of aerobic and anaerobic microorganisms as well as fungi, positive blood cultures can be obtained in 95% of the patients. Antibiotics may be discontinued temporarily in pretreated patients. Bactericidal antibiotics are indicated. The following rule is valid as a guideline for adequate antibacterial chemotherapy: at maximal concentration after antibiotic administration, a bactericidal effect should still be demonstrated after 1:8 dilution of the patient's serum. Prior to receipt of blood culture findings, in forms tending to be subacute, treatment should be directed at streptococci and enterococci. If the course is more acute, in the presence of an intracardiac foreign body or in intravenous drug users, the antibiotic employed should also be effective against staphylococci.(ABSTRACT TRUNCATED AT 250 WORDS)