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Enterococcal Infections


Larry M. Bush

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

Maria T. Vazquez-Pertejo

, MD, FACP, Wellington Regional Medical Center

Last full review/revision Mar 2021| Content last modified Mar 2021

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 of Enterococcal Infections

  • Varies by site of infection and susceptibility testing

(See also the American Heart Association's Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications.)

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 an aminopenicillin, such as 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, tigecycline, 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.


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, oritavancin, 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.

Enterococci can incorporate exogenously produced folates and thereby reverse the effect of trimethoprim and sulfamethoxazole; therefore, therapy with these drugs may fail despite apparent in vitro susceptibility (for this reason, TMP/SMX is often left off of susceptibility panels for enterococci).

More Information

The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

  • Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications: A statement for health care practitioners from the American Heart Association

Drugs Mentioned In This Article

Drug Name Select Trade
quinupristin/dalfopristin SYNERCID
Piperacillin/tazobactam ZOSYN
trimethoprim No US brand name
eravacycline Eravacycline
amoxicillin AMOXIL
tigecycline TYGACIL
ceftriaxone ROCEPHIN
oritavancin ORBACTIV
gentamicin GENOPTIC
vancomycin VANCOCIN
daptomycin CUBICIN
fosfomycin MONUROL
tedizolid SIVEXTRO
aztreonam AZACTAM
ertapenem INVANZ
meropenem MERREM
linezolid ZYVOX

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