Enterococcus: Difference between revisions
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Enterococcus
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Revision as of 23:15, 12 March 2022
Background
Microbiology
- Genus of facultative anaerobic, non-spore-forming, alpha- or gamma-hemolytic, catalase negative, Gram-positive cocci
- Grows on bile esculin agar
- PYR positive
- Most are Lancefield group D
- Commensal gut flora
- Increasing antibiotic resistance
Species
- E. faecalis
- More common (90-95%)
- More commonly genitourinary source
- More susceptible to antibiotics
- E. faecium
- Less common (5-10%)
- More commonly gastrointestinal source
- Less susceptible to antibiotics
- Most common VRE
- E. gallinarum
- E. casseliflavus
- E. hirae, a rare zoonotic pathogen from chickens that can cause bacteremia and endocarditis
Vancomycin Resistance
- Vancomycin binds to d-Ala-d-Ala pentapeptids, interfering with cell wall synthesis
- VanA: most common. Mutation to d-Ala-d-Lac, leading to high resistance to glycopeptides.
- VanB: more common in E. faecium in Australia
- VanC: chromosomal resistance on E. gallinarum and E. casseliflavus
Management
- Vancomycin is usually reliable (except for E. gallinarum and E. casseliflavus)
- Ampicillin is preferred for susceptible strains
- Inherent resistance to cephalosporins
- Resistant to ertapenem, but ampicillin-susceptible strains are often susceptible to imipenem and (somewhat) meropenem
VRE
- Daptomycin, doxycycline, linezolid, tedizolid, oritavancin, quinupristin-dalfopristin (for E. faecium)
References
- ^ James H. Jorgensen, Sharon A. Crawford, Cynthia C. Kelly, Jan E. Patterson. In VitroActivity of Daptomycin against Vancomycin-Resistant Enterococci ofVarious Van Types and Comparison of Susceptibility TestingMethods. Antimicrobial Agents and Chemotherapy. 2003;47(12):3760-3763. doi:10.1128/aac.47.12.3760-3763.2003.
