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] It is among the main constituents of some probiotic food supplements.[2] 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.[3] Root canal-treated teeth are about nine times more likely to harbor E. faecalis than cases of primary infections.[4]

Contents

Physiology

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.

Pathogenesis

E. faecalis can cause endocarditis and bacteremia, urinary tract infections (UTI), meningitis, and other infections in humans.[5] In the United States, E. faecalis is associated with nosocomial infections including catheter-associated UTI, central line-associated bloodstream infection, and surgical site infections.[6] 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.[7][8][9] A plasmid-encoded factor called "aggregation substance" is also important for virulence in animal models of infection.[8][10]

Antibacterial resistance

E. faecalis is resistant to many commonly used antimicrobial agents (aminoglycosides, aztreonam, cephalosporins, clindamycin, the semisynthetic penicillins nafcillin and oxacillin, and trimethoprim-sulfamethoxazole). Resistance to vancomycin in E. faecalis is becoming more common.[11][12] Treatment options for vancomycin-resistant E. faecalis include linezolid and daptomycin, although ampicillin is preferred if the bacteria are susceptible.[13] Quinupristin/dalfopristin can be used to treat Enterococcus faecium but not E. faecalis.[13]

Historical

Prior to 1984, enterococci were members of the genus Streptococcus: thus E. faecalis was known as Streptococcus faecalis.[14]

References

  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. ^ E.g. ThreeLac and FiveLac: see [1].
  3. ^ Molander A, Reit C, Dahlen G, Kvist T: Microbiological status of root-filled teeth with apical periodontitis, Int Endod J 31:1, 1998
  4. ^ Rocas, IN, Siquiera JF, Jr., Santos KR: Association of Enterococcus faecalis with different forms of periradicular diseases, J Endod 30:315, 2004.
  5. ^ Murray, BE. (Jan 1990). "The life and times of the Enterococcus.". Clin Microbiol Rev 3 (1): 46–65. PMID 2404568. 
  6. ^ 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. 
  7. ^ 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. 
  8. ^ 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. 
  9. ^ 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. 
  10. ^ 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. 
  11. ^ 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. http://linkinghub.elsevier.com/retrieve/pii/S0924-8579(07)72177-5. 
  12. ^ Courvalin P (January 2006). "Vancomycin resistance in gram-positive cocci". Clin. Infect. Dis. 42 Suppl 1: S25–34. doi:10.1086/491711. PMID 16323116. http://www.journals.uchicago.edu/doi/abs/10.1086/491711?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dncbi.nlm.nih.gov. 
  13. ^ 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. 
  14. ^ 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. 

See also

Bacilli
BEA+: Enterococcus faecalis (Urinary tract infection) · Enterococcus faecium
Clostridia
Clostridium (spore-forming)
Peptostreptococcus (non-spore forming)
Mollicutes

M: BAC

bact (clas)

gr+f/gr+a(t)/gr-p(c)/gr-o

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