Enterococcus faecalis

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Enterococcus faecalis
Scientific classification
Domain: Bacteria
Kingdom: Eubacteria
Phylum: Firmicutes
Class: Bacilli
Order: Lactobacillales
Family: Enterococcaceae
Genus: Enterococcus
Species: faecalis
Binomial name
Enterococcus faecalis
Not to be confused with Enterococcus faecium.

Enterococcus faecalis – formerly classified as part of the Group D Streptococcus system – is a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans and other mammals.[1] Like other species in the genus Enterococcus, E. faecalis can cause life-threatening infections in humans, especially in the nosocomial (hospital) environment, where the naturally high levels of antibiotic resistance found in E. faecalis contribute to its pathogenicity.[1] E. faecalis has been frequently found in root canal-treated teeth in prevalence values ranging from 30% to 90% of the cases.[2] Root canal-treated teeth are about nine times more likely to harbor E. faecalis than cases of primary infections.[3]

Contents

Physiology [edit]

E. faecalis is a nonmotile, facultatively anaerobic microbe; it ferments glucose without gas production, and does not produce a catalase reaction with hydrogen peroxide. It can produce a pseudocatalase reaction if grown on blood agar. The reaction is usually weak. It produces a reduction of litmus milk, but does not liquefy gelatin. Growth on nutrient broth is consistent with being facultatively anaerobic.They catabolize a variety of energy sources including carbohydrates, glycerol, lactate,malate, citrate, arginine, agmatine, and many � keto acids . Enterococci survive very harsh environments including extreme alkaline pH (9.6) and salt concentrations. They resist bile salts, detergents, heavy metals, ethanol, azide,and desiccation . They can grow in the range of 10 to 45°C and survive a temperature of 60°C for 30 min.[stuart et al 2006]

Pathogenesis [edit]

E. faecalis can cause endocarditis and bacteremia, urinary tract infections (UTI), meningitis, and other infections in humans.[4][5] Several virulence factors are thought to contribute to E. faecalis infections. A plasmid-encoded hemolysin, called the cytolysin, is important for pathogenesis in animal models of infection, and the cytolysin in combination with high-level gentamicin resistance is associated with a five-fold increase in risk of death in human bacteremia patients.[6][7][8] A plasmid-encoded factor called "aggregation substance" is also important for virulence in animal models of infection.[7][9]

Antibacterial resistance [edit]

E. faecalis is resistant to many commonly used antimicrobial agents (aminoglycosides, aztreonam, cephalosporins, clindamycin, the semisynthetic penicillins nafcillin and oxacillin, and trimethoprim-sulfamethoxazole).[citation needed] Resistance to vancomycin in E. faecalis is becoming more common.[10][11] Treatment options for vancomycin-resistant E. faecalis include linezolid and daptomycin, although ampicillin is preferred if the bacteria are susceptible.[12] Quinupristin/dalfopristin can be used to treat Enterococcus faecium but not E. faecalis.[12]

Survival and Virulence Factors [edit]

  • Endures prolonged periods of nutritional deprivation
  • Binds to dentin and proficiently invades dentinal tubules
  • Alters host responses
  • Suppresses the action of lymphocytes
  • Possesses lytic enzymes, cytolysin, aggregation substance,pheromones, and lipoteichoic acid
  • Utilizes serum as a nutritional source
  • Resists intracanal medicaments (i.e. Ca(OH)2)
    • Maintains pH homeostasis
    • Properties of dentin lessen the effect of calcium hydroxide
  • Competes with other cells
  • Forms a biofilm

[Review Article stuart et al JOE 2006]

Historical [edit]

Prior to 1984, enterococci were members of the genus Streptococcus: thus E. faecalis was known as Streptococcus faecalis.[13]

See also [edit]

References [edit]

  1. ^ a b Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 294––5. ISBN 0-8385-8529-9. 
  2. ^ Molander A, Reit C, Dahlen G, Kvist T: Microbiological status of root-filled teeth with apical periodontitis, Int Endod J 31:1, 1998
  3. ^ Rocas, IN, Siquiera JF, Jr., Santos KR: Association of Enterococcus faecalis with different forms of periradicular diseases, J Endod 30:315, 2004.
  4. ^ Murray, BE. (Jan 1990). "The life and times of the Enterococcus.". Clin Microbiol Rev 3 (1): 46–65. PMID 2404568. 
  5. ^ Hidron AI, Edwards JR, Patel J, et al. (November 2008). "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 29 (11): 996–1011. doi:10.1086/591861. PMID 18947320. 
  6. ^ Huycke, MM.; Spiegel, CA.; Gilmore, MS. (Aug 1991). "Bacteremia caused by hemolytic, high-level gentamicin-resistant Enterococcus faecalis.". Antimicrob Agents Chemother 35 (8): 1626–34. PMID 1929336. 
  7. ^ a b Chow, JW.; Thal, LA.; Perri, MB.; Vazquez, JA.; Donabedian, SM.; Clewell, DB.; Zervos, MJ. (Nov 1993). "Plasmid-associated hemolysin and aggregation substance production contribute to virulence in experimental enterococcal endocarditis.". Antimicrob Agents Chemother 37 (11): 2474–7. PMID 8285637. 
  8. ^ Ike, Y.; Hashimoto, H.; Clewell, DB. (Aug 1984). "Hemolysin of Streptococcus faecalis subspecies zymogenes contributes to virulence in mice.". Infect Immun 45 (2): 528–30. PMID 6086531. 
  9. ^ Hirt, H.; Schlievert, PM.; Dunny, GM. (Feb 2002). "In vivo induction of virulence and antibiotic resistance transfer in Enterococcus faecalis mediated by the sex pheromone-sensing system of pCF10.". Infect Immun 70 (2): 716–23. PMID 11796604. 
  10. ^ Amyes SG (May 2007). "Enterococci and streptococci". Int. J. Antimicrob. Agents. 29 Suppl 3: S43–52. doi:10.1016/S0924-8579(07)72177-5. PMID 17659211. 
  11. ^ Courvalin P (January 2006). "Vancomycin resistance in gram-positive cocci". Clin. Infect. Dis. 42 Suppl 1: S25–34. doi:10.1086/491711. PMID 16323116. 
  12. ^ a b Arias, CA.; Contreras, GA.; Murray, BE. (Jun 2010). "Management of multidrug-resistant enterococcal infections.". Clin Microbiol Infect 16 (6): 555–62. doi:10.1111/j.1469-0691.2010.03214.x. PMID 20569266. 
  13. ^ 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. 
Bacilli
BEA+: Enterococcus faecalis (Urinary tract infection) · Enterococcus faecium
Clostridia
Clostridium (spore-forming)
Peptostreptococcus (non-spore forming)
Mollicutes

M: BAC

drug (J1p, w, n, m, vacc)
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