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Specimen: Blood Diagnosis: Endocarditis Enterococcus faecalis

Specimen: Blood Diagnosis: Endocarditis Enterococcus faecalis. Case #11. ampicillin S vancomycin S gentamicin synergy S streptomycin synergy S. Should we add any comment to the report?. Enterococcus spp . CLSI “Rx” Comment.

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Specimen: Blood Diagnosis: Endocarditis Enterococcus faecalis

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  1. Specimen: BloodDiagnosis: EndocarditisEnterococcus faecalis Case #11 ampicillin S vancomycin S gentamicin synergy S streptomycin synergy S Should we add any comment to the report?

  2. Enterococcus spp.CLSI “Rx” Comment “Rx: Combination therapy of ampicillin, penicillin, or vancomycin (for susceptible strains),plus an aminoglycoside, is usually indicated for serious enterococcal infections, such as endocarditis, unless high-level resistance to both gentamicin and streptomycin is documented; such combinations are predicted to result in synergistic killing of the enterococcus.” CLSI M100-S21. Table 2D.

  3. Enterococcus spp. HLAR (Synergy) Screening • Disk diffusion • 120 µg gentamicin; 300 µg streptomycin •  10 mm = NO HLAR • 6 mm = HLAR • 7-9 mm = inconclusive; perform MIC • MIC screen • gentamicin: 500 µg/ml • streptomycin: 1000 µg/ml (broth); 2000 µg/ml (agar) • no growth = NO HLAR • Perform testing when combination therapy is desired (e.g., endocarditis)

  4. Enterococcus spp. Aminoglycoside-Modifying Enzymes strep gent tob amk/kan 6-AAD + - - - 3’APH - - - + (test kan) 2”APH/6’AAC - + + + 6’AAC* - - + + * found in all E. faecium + = enzyme modifies drug; drug NOT synergistic - = enzyme does not modify drug; drug synergistic

  5. Enterococcus spp. HLAR Test Gent Strep Choice of aminoglycoside S S either S R gentamicin R S streptomycin R* R none *HLAR to gentamicin confers HLAR to amikacin and tobramycin

  6. Enterococcus spp. Predicting Synergy Susc Res Susc“synergy“ no synergy Res no synergy no synergy Aminoglycoside or HLAR screen Cell wall active agent* *ampicillin, penicillin, or vancomycin

  7. Final Report Specimen: BloodDiagnosis: EndocarditisEnterococcus faecalis Case #11 ampicillin S vancomycin S gentamicin synergy S streptomycin synergy S “Serious enterococcal infections need combination therapy with ampicillin or vancomycin plus an aminoglycoside. Synergy occurs only when both drugs in the combination are “S””

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