Enterococcus sp. infection in lung tissue
Scientific classification

Enterococcus is a genus of lactic acid bacteria of the phylum Firmicutes.

Enterococci are Gram-positive cocci that often occur in pairs or short chains. They look like streptococci.[1] Two species are regular gut flora organisms in the intestines of humans: E. faecalis (90-95%) and E. faecium (5-10%).

Physiology and classification

Enterococci are "facultative anaerobic organisms". This means they can live in both oxygen-rich and oxygen-poor environments.[2]

Members of the genus Enterococcus were classified as Group D Streptococcus until 1984. Genomic DNA analysis showed they were a separate genus.[3]


Important infections caused by Enterococcus include urinary tract infections, bacterial endocarditis, diverticulitis, and meningitis.

Sensitive strains of these bacteria can be treated with ampicillin, penicillin and vancomycin.[4] Urinary tract infections can be treated by antibiotics, but many virulent strains of Enterococcus are resistant. From a medical standpoint, an important feature of this genus is the high level of intrinsic antibiotic resistance. This rules out some important antibiotics.[5]


  1. Template:Cite book
  2. Template:Cite book
  3. Schleifer KH; Kilpper-Balz R (1984). "Transfer of Streptococcus faecalis and Streptococcus faecium to the genus Enterococcus nom. rev. as Enterococcus faecalis comb. nov. and Enterococcus faecium comb. nov.". Int. J. Sys. Bacteriol. 34: 31–34. doi:10.1099/00207713-34-1-31. 
  4. Template:Cite book
  5. Ryan K.J. & Ray C.G. (eds) 2004. Sherris medical microbiology. 4th ed, McGraw Hill, 294–5. Template:Catalog lookup linkScript error: No such module "check isxn".