Microbiology of enterococci
- Barbara E Murray, MD
Barbara E Murray, MD
- Professor of Medicine, Microbiology and Molecular Genetics
- University of Texas at Houston 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:
- Murray BE. The life and times of the Enterococcus. Clin Microbiol Rev 1990; 3:46.
- Wade JJ. Enterococcus faecium in hospitals. Eur J Clin Microbiol Infect Dis 1997; 16:113.
- Gross PA, Harkavy LM, Barden GE, Flower MF. The epidemiology of nosocomial enterococcal urinary tract infection. Am J Med Sci 1976; 272:75.
- Emori TG, Gaynes RP. An overview of nosocomial infections, including the role of the microbiology laboratory. Clin Microbiol Rev 1993; 6:428.
- Schleifer KH, Kilpper-Balz R. Transfer of Streptococcus faecalis and Streptococcus faecium to the genus Enterococcus nom. rev. as Enterococcus faecalis comb. nov. and Enterococcus faecium comb. Int J Syst Bacteriol 1984; 34:31.
- Teixeira LM, Carvalho MS, Facklam RR. Enterococcus. In: Manual of Clinical Microbiology, Murray PR, Baron EJ, Jorgensen JH, LLandry ML, Pfaller MA (Eds), ASM Press, Washington, DC 2007.
- Hidron AI, Edwards JR, Patel J, et al. NHSN annual update: antimicrobial-resistant pathogens associated with healthcare-associated infections: annual summary of data reported to the National Healthcare Safety Network at the Centers for Disease Control and Prevention, 2006-2007. Infect Control Hosp Epidemiol 2008; 29:996.
- Teixeira LM, Facklam RR, Steigerwalt AG, et al. Correlation between phenotypic characteristics and DNA relatedness within Enterococcus faecium strains. J Clin Microbiol 1995; 33:1520.
- Coque TM, Murray BE. Identification of Enterococcus faecalis strains by DNA hybridization and pulsed-field gel electrophoresis. J Clin Microbiol 1995; 33:3368.
- Singh KV, Coque TM, Weinstock GM, Murray BE. In vivo testing of an Enterococcus faecalis efaA mutant and use of efaA homologs for species identification. FEMS Immunol Med Microbiol 1998; 21:323.
- Tyrrell GJ, Bethune RN, Willey B, Low DE. Species identification of enterococci via intergenic ribosomal PCR. J Clin Microbiol 1997; 35:1054.
- Depardieu F, Perichon B, Courvalin P. Detection of the van alphabet and identification of enterococci and staphylococci at the species level by multiplex PCR. J Clin Microbiol 2004; 42:5857.
- Hayes JR, McIntosh AC, Qaiyumi S, et al. High-frequency recovery of quinupristin-dalfopristin-resistant Enterococcus faecium isolates from the poultry production environment. J Clin Microbiol 2001; 39:2298.
- McDonald LC, Rossiter S, Mackinson C, et al. Quinupristin-dalfopristin-resistant Enterococcus faecium on chicken and in human stool specimens. N Engl J Med 2001; 345:1155.
- Sørensen TL, Blom M, Monnet DL, et al. Transient intestinal carriage after ingestion of antibiotic-resistant Enterococcus faecium from chicken and pork. N Engl J Med 2001; 345:1161.
- Schaberg DR, Culver DH, Gaynes RP. Major trends in the microbial etiology of nosocomial infection. Am J Med 1991; 91:72S.
- Mikulska M, Del Bono V, Raiola AM, et al. Blood stream infections in allogeneic hematopoietic stem cell transplant recipients: reemergence of Gram-negative rods and increasing antibiotic resistance. Biol Blood Marrow Transplant 2009; 15:47.
- Bedini A, Codeluppi M, Cocchi S, et al. Gram-positive bloodstream infections in liver transplant recipients: incidence, risk factors, and impact on survival. Transplant Proc 2007; 39:1947.
- Suppola JP, Volin L, Valtonen VV, Vaara M. Overgrowth of Enterococcus faecium in the feces of patients with hematologic malignancies. Clin Infect Dis 1996; 23:694.
- Galloway-Peña J, Roh JH, Latorre M, et al. Genomic and SNP analyses demonstrate a distant separation of the hospital and community-associated clades of Enterococcus faecium. PLoS One 2012; 7:e30187.
- Palmer KL, Godfrey P, Griggs A, et al. Comparative genomics of enterococci: variation in Enterococcus faecalis, clade structure in E. faecium, and defining characteristics of E. gallinarum and E. casseliflavus. MBio 2012; 3:e00318.
- Lebreton F, van Schaik W, McGuire AM, et al. Emergence of epidemic multidrug-resistant Enterococcus faecium from animal and commensal strains. MBio 2013; 4.
- Rice LB, Carias L, Rudin S, et al. A potential virulence gene, hylEfm, predominates in Enterococcus faecium of clinical origin. J Infect Dis 2003; 187:508.
- Nallapareddy SR, Weinstock GM, Murray BE. Clinical isolates of Enterococcus faecium exhibit strain-specific collagen binding mediated by Acm, a new member of the MSCRAMM family. Mol Microbiol 2003; 47:1733.
- Leavis HL, Bonten MJ, Willems RJ. Identification of high-risk enterococcal clonal complexes: global dispersion and antibiotic resistance. Curr Opin Microbiol 2006; 9:454.
- Zhang X, Top J, de Been M, et al. Identification of a genetic determinant in clinical Enterococcus faecium strains that contributes to intestinal colonization during antibiotic treatment. J Infect Dis 2013; 207:1780.
- Sillanpää J, Prakash VP, Nallapareddy SR, Murray BE. Distribution of genes encoding MSCRAMMs and Pili in clinical and natural populations of Enterococcus faecium. J Clin Microbiol 2009; 47:896.