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Enterococcal Infections

By

Larry M. Bush

, MD, FACP, Charles E. Schmidt College of Medicine, Florida Atlantic University;


Maria T. Vazquez-Pertejo

, MD, FCAP, Wellington Regional Medical Center

Last full review/revision Jun 2019| Content last modified Jun 2019
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Enterococci are gram-positive, facultative anaerobic organisms. Enterococcus faecalis and E. faecium cause a variety of infections, including endocarditis, urinary tract infections, prostatitis, intra-abdominal infection, cellulitis, and wound infection as well as concurrent bacteremia.

Enterococci are part of the normal intestinal flora. They used to be classified as group D streptococci but are now considered a separate genus. There are > 17 species, but E. faecalis and E. faecium most commonly cause infections in humans.

Enterococci typically cause

Treatment

  • Varies by site of infection and susceptibility testing

Enterococci associated with endocarditis are difficult to eradicate unless a combination of certain cell wall–active drugs (eg, penicillin, ampicillin, amoxicillin, piperacillin, vancomycin) plus an aminoglycoside (eg, gentamicin, streptomycin) is used to achieve bactericidal activity. However, some cell wall–active drugs have limited or no activity against enterococci; they include nafcillin, oxacillin, ticarcillin, ertapenem, most cephalosporins, and aztreonam. E. faecium are more resistant to penicillin than E. faecalis. When an aminoglycoside cannot be used, the combination of penicillin or ampicillin plus ceftriaxone is an effective alternative for the treatment of E. faecalis endocarditis. Imipenem and, to a lesser degree, meropenem are active against E. faecalis.

For complicated skin infections due to vancomycin-susceptible enterococci, daptomycin, linezolid, tedizolid, tigecycline, and omadacycline are effective treatment options.

Piperacillin/tazobactam, imipenem or meropenem, and eravacycline are recommended for complicated intra-abdominal infections when enterococci are known or presumed to be involved.

Urinary tract infections do not require bactericidal therapy and, if the causative organism is sensitive, are usually treated with a single antibiotic such as ampicillin. Nitrofurantoin and fosfomycin are often effective against vancomycin-resistant enterococcal urinary tract infection.

Resistance

In the past several decades, resistance to multiple antimicrobial drugs has increased rapidly, especially among E. faecium.

Resistance to aminoglycosides (eg, gentamicin, streptomycin), particularly with E. faecium, continues to emerge.

Vancomycin-resistant enterococci (VRE) may also be resistant to other glycopeptides (eg, teicoplanin), aminoglycosides, and cell wall–active beta-lactams (eg, penicillin G, ampicillin). When identified, infected patients are strictly isolated. Recommended treatment includes streptogramins (quinupristin/dalfopristin for E. faecium only) and oxazolidinones (linezolid, tedizolid). Daptomycin, tigecycline, and eravacycline have in vitro activity against VRE and may be off-label treatment options.

Beta-lactamase–producing enterococci are occasionally problematic, particularly when large numbers of organisms are present in tissues (eg, in endocarditis vegetation). Resistance may be present clinically even though the organism appears susceptible based on standard testing. Vancomycin or combination beta-lactam/beta-lactamase inhibitor antibiotics (eg, piperacillin/tazobactam, ampicillin/sulbactam) can be used.

More Information

Drugs Mentioned In This Article

Drug Name Select Trade
SYNERCID
ZOSYN
FURADANTIN, MACROBID, MACRODANTIN
No US brand name
Eravacycline
AMOXIL
TYGACIL
ROCEPHIN
GENOPTIC
VANCOCIN
CUBICIN
MONUROL
SIVEXTRO
AZACTAM
NALLPEN IN PLASTIC CONTAINER
INVANZ
MERREM
ZYVOX
BACTOCILL IN PLASTIC CONTAINER
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NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
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