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Treatment of endocarditis caused by relatively resistant nonenterococcal streptococci: is penicillin enough?
1University of Medicine and Dentistry/Robert Wood Johnson Medical School, Camden, New Jersey.
Abstract:
Most cases of endocarditis are caused by nonenterococcal streptococci. Some of these organisms are classified as relatively resistant to penicillin on the basis of minimum inhibitory concentrations (MICs) greater than 0.1-0.2 microgram/mL. Almost all authorities recommend that endocarditis caused by relatively resistant streptococci be treated with high doses of penicillin combined with 2-6 weeks of an aminoglycoside rather than the potentially shorter, less toxic, and more flexible regimens used for exquisitely sensitive streptococci (MIC, less than 0.1-0.2 microgram of penicillin/mL). The data to support this recommendation are limited and inconclusive. We review the relevant clinical experience, experimental models, and theoretical considerations. Penicillin alone is probably adequate therapy for most cases of native valve endocarditis caused by relatively resistant streptococci; in certain patients, it may be the preferred treatment.
Insights
Penicillin alone may be sufficient for treating endocarditis caused by penicillin-resistant streptococci. Current treatment guidelines for streptococcal endocarditis may not be fully supported by available data.
Area of Science:
- Infectious Diseases
- Cardiology
- Microbiology
Background:
- Endocarditis is primarily caused by nonenterococcal streptococci.
- Some strains exhibit relative penicillin resistance (MIC > 0.1-0.2 µg/mL).
- Current treatment often involves high-dose penicillin plus aminoglycosides for resistant strains.
Purpose of the Study:
- To evaluate the evidence supporting current treatment recommendations for penicillin-resistant streptococcal endocarditis.
- To determine if penicillin monotherapy is adequate for certain cases.
Main Methods:
- Review of clinical case studies.
- Analysis of experimental models.
- Consideration of theoretical data.
Main Results:
- Data supporting combined penicillin-aminoglycoside therapy are limited and inconclusive.
- Penicillin monotherapy is likely adequate for most native valve endocarditis cases caused by relatively resistant streptococci.
- Penicillin alone may be the preferred treatment for select patients.
Conclusions:
- Current treatment guidelines for penicillin-resistant streptococcal endocarditis may require re-evaluation.
- Penicillin monotherapy is a viable and potentially preferred option for specific patient populations.
- Further research is needed to refine treatment strategies for streptococcal endocarditis.