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Abstract:
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)
Insights
Infective endocarditis is most commonly caused by streptococci, with enterococci and staphylococci also significant contributors. Prompt diagnosis and appropriate bactericidal antibiotic therapy, guided by blood cultures, are crucial for effective treatment.
Area of Science:
- Cardiology
- Infectious Diseases
- Microbiology
Context:
- Infective endocarditis (IE) is a serious infection affecting the heart valves and inner lining of the heart.
- Common etiologies include viridans streptococci (65-85%), enterococci (5-15%), staphylococci (5-15%), and gram-negative bacteria (2-6%).
- Specific patient populations are at increased risk, such as older men, younger women, intravenous drug users, and those with intravascular devices or immunosuppression.
Purpose:
- To outline the primary causative agents of infective endocarditis.
- To identify risk factors and patient demographics associated with specific pathogens.
- To provide guidelines for diagnostic blood cultures and empirical antibiotic therapy.
Summary:
- Viridans streptococci and other nonhemolytic streptococci are the predominant causes of infective endocarditis.
- Enterococci, staphylococci, and gram-negative bacteria are less common but significant pathogens.
- Diagnostic blood cultures are essential, with 95% positivity achievable using appropriate techniques.
- Bactericidal antibiotic therapy is indicated, with treatment tailored based on clinical presentation and suspected pathogens.
Impact:
- Establishes the etiological spectrum of infective endocarditis for targeted treatment strategies.
- Highlights the importance of prompt and accurate diagnosis through blood cultures.
- Provides a framework for empirical antibiotic selection in critically ill patients prior to definitive culture results.