Microbiology of enterococci
- Barbara E Murray, MD
Barbara E Murray, MD
- Professor of Medicine, Microbiology and Molecular Genetics
- University of Texas Health Science Center at Houston, McGovern Medical School
A number of the characteristic features of enterococci (formerly called group D streptococci) have been recognized for at least 100 years, including their presence in feces and sewage, their ability to cause endocarditis and urinary tract infections (UTIs), and their ability to survive harsh environmental conditions including drying, high temperatures, and exposure to some antiseptics [1,2].
The common name Enterococcus, derived from the French "entérocoque" used in an 1899 publication, points out that these bacteria are cocci of intestinal (enteric) origin, and the 1906 use of Streptococcus faecalis and the 1919 use of Streptococcus faecium also emphasized their presence in feces.
Subsequent studies confirmed these early observations. Most humans and animals have enterococci in their intestinal tract; the counts in healthy humans often range from 105 to 107 bacteria per gram of stool.
●Enterococci, particularly Enterococcus faecalis, are a common cause of endocarditis (5 to 15 percent of community-acquired endocarditis and up to 30 percent of nosocomially acquired endocarditis) and can be a common cause of nosocomial urinary tract infections (being recovered from up to 15 to 20 percent of UTIs in the hospital setting) [3,4].
Enterococci are gram-positive cocci that form short- to medium-length chains. In the 1930s, Lancefield devised a serologic typing system that classified enterococci as group D streptococci, along with some organisms (eg, Streptococcus gallolyticus, formerly S. bovis) that differed from enterococci in a number of other features. In 1937, Sherman divided streptococci into the pyogenic, viridans, lactic, and enterococcal groups. Enterococci were characterized by the following features:
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