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Glycopeptide tolerance in bacteria causing endocarditis
J D Perry1, A L Jones, F K Gould
1Department of Microbiology, Freeman Hospital, Newcastle upon Tyne, UK. homeresearch@compuserve.com
Abstract:
Glycopeptides have been recommended as therapy for endocarditis. MICs and MBCs of vancomycin and teicoplanin were compared for 100 isolates from patients with proven bacterial endocarditis. MICs were generally lower for teicoplanin and tolerance to both agents was common. Almost all isolates of enterococci were tolerant to both glycopeptides. Among the streptococci, 78% were tolerant to teicoplanin and 57% to vancomycin. Similar findings were demonstrated for staphylococci. Although isolates appear sensitive to glycopeptides, bactericidal activity cannot always be predicted. If a glycopeptide is indicated for treatment of endocarditis, combination therapy with a suitable aminoglycoside should be considered unless MBC testing can be performed.
Insights
Glycopeptides like vancomycin are used for endocarditis, but tolerance is common in bacteria. This means bactericidal activity may not be predicted, suggesting combination therapy might be needed.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Glycopeptides are recommended treatments for bacterial endocarditis.
- Understanding the activity of these agents against common pathogens is crucial.
Purpose of the Study:
- To compare the Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal Concentrations (MBCs) of vancomycin and teicoplanin.
- To assess the prevalence of tolerance to these glycopeptides in bacterial endocarditis isolates.
Main Methods:
- Collected 100 bacterial isolates from patients with confirmed endocarditis.
- Determined MICs and MBCs for vancomycin and teicoplanin.
- Evaluated bacterial tolerance to both glycopeptide agents.
Main Results:
- Teicoplanin generally exhibited lower MICs compared to vancomycin.
- Bacterial tolerance to both vancomycin and teicoplanin was frequently observed across Enterococci, Streptococci, and Staphylococci species.
- Specifically, 78% of Streptococci and 57% of Staphylococci isolates showed tolerance to teicoplanin and vancomycin, respectively.
Conclusions:
- Despite appearing sensitive based on MICs, the bactericidal activity of glycopeptides in endocarditis treatment cannot always be reliably predicted.
- For endocarditis cases requiring glycopeptide therapy, consider combination treatment with an aminoglycoside, especially if MBC testing is not feasible.