Enterococcus species (other)

• E. avium group
• E. caccae
• E. casseliflavus
• E. dispar
• E. durans
• E. gallinarum
• E. hirae
• E. mundtii

Gram Stain

• Gram positive cocci in pairs and short chains (aerobic)

Clinical Significance

These organisms are found in environmental sources including soil, water, plants, animals, birds, and insects. Some species may be part of the human gastrointestinal flora.

Although occasionally recovered from clinical specimens, their pathogenic role is often uncertain. They have been implicated in endocarditis (native/prosthetic valve), meningitis, endophthalmitis, and urinary tract infections.

E. avium - associated with bacteremia of biliary or intra-abdominal source.

E. casseliflavus/E. gallinarum – associated with bacteremia (typically polymicrobial) which tends to occur in immunocompromised patients (especially those with malignancy).

E. hirae - considered a zoonotic organism that has been associated with prosthetic valve endocarditis, hepatobiliary sepsis, and urinary tract infections.

E. mundtii - associated with ophthalmitis and urinary tract infections.

Usual Susceptibility Pattern

These organisms exhibit variable susceptibility to ampicillin and are intrinsically resistant to cephalosporins, clindamycin, macrolides, tetracyclines, quinolones, fusidic acid, and TMP/SMX.

E. casseliflavus and E. gallinarum exhibit intrinsic low level resistance to vancomycin.

Vancomycin resistance has been reported in E. mundtii.