Vancomycin-resistant Enterococcus

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SEM micrograph of vancomycin-resistant enterococci

Vancomycin-resistant Enterococcus, or vancomycin-resistant enterococci (VRE), are bacterial strains of the genus Enterococcus that are resistant to the antibiotic vancomycin.[1]

History and biology[edit]

To become vancomycin-resistant, vancomycin-sensitive enterococci typically obtain new DNA in the form of plasmids or transposons which encode genes that confer vancomycin resistance.[2] This acquired vancomycin resistance is distinguished from the natural vancomycin resistance of certain enterococcal species including E. gallinarum and E. casseliflavus.[3]

High-level vancomycin-resistant E. faecalis and E. faecium are clinical isolates first documented in the 1980's.[4] In the United States, vancomycin-resistant E. faecium was associated with 4% of healthcare-associated infections reported to the Centers for Disease Control and Prevention National Healthcare Safety Network from January 2006 to October 2007.[5] VRE can be carried by healthy people who have come into contact with the bacteria, usually in a hospital[6] (nosocomial infection),[7] although it is thought that a significant percentage of intensively farmed chicken also carry VRE.[8]

Mechanism of acquired resistance[edit]

Six different types of vancomycin resistance are shown by enterococcus : Van-A, Van-B, Van-C, Van-D, Van-E and Van-G.[9] The significance is that Van-A VRE is resistant to both vancomycin and teicoplanin,[10] Van-B VRE is resistant to vancomycin but susceptible to teicoplanin,[11][12] and Van-C is only partly resistant to vancomycin, and susceptible to teicoplanin.

The mechanism of resistance to vancomycin found in enterococcus involves the alteration peptidoglycan synthesis pathway.[13] The D-alanyl-D-lactate variation results in the loss of one hydrogen-bonding interaction (four, as opposed to five for D-alanyl-D-alanine) being possible between vancomycin and the peptide. The D-alanyl-D-serine variation causes a six-fold loss of affinity between vancomycin and the peptide, likely due to steric hindrance.[14][15]

Treatment of infection[edit]


Cephalosporin use is a risk factor for colonization and infection by VRE, and restriction of cephalosporin usage has been associated with decreased VRE infection and transmission in hospitals.[16] Lactobacillus rhamnosus GG (LGG), a strain of L. rhamnosus, was used successfully for the first time to treat gastrointestinal carriage of VRE.[17] In the US, linezolid is commonly used to treat VRE.[18]

See also[edit]


  1. ^ "Vancomycin-resistant Enterococci (VRE) in Healthcare Settings". VRE in Healthcare Settings - HAI. CDC. Retrieved 2015-06-09. 
  2. ^ Gould, Dinah; Brooker, Christine (2008-08-20). Infection Prevention and Control: Applied Microbiology for Healthcare. Palgrave Macmillan. ISBN 9781137045928. 
  3. ^ "VRE and the Clinical Laboratory - HAI". Healthcare-associated Infections. CDC. Retrieved 2015-06-09. 
  4. ^ Robinson, D. Ashley; Feil, Edward J.; Falush, Daniel (2010-03-16). Bacterial Population Genetics in Infectious Disease. John Wiley & Sons. ISBN 9780470600115. 
  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. ^ "Diseases and Organisms in Healthcare Settings". Healthcare-associated Infections (HAIs). CDC. Retrieved 2015-06-09. 
  7. ^ Kouchak, Farideh; Askarian, Mehrdad (2012). "Nosocomial Infections: The Definition Criteria". Iranian Journal of Medical Sciences 37 (2): 72–73. PMC 3470069. PMID 23115435. 
  8. ^ Nilsson, Oskar (2012). "Vancomycin resistant enterococci in farm animals – occurrence and importance". Infection Ecology & Epidemiology 2. doi:10.3402/iee.v2i0.16959. PMC 3426332. PMID 22957131. 
  9. ^ Fong, I. W.; Drlica, Karl (2007-11-15). Antimicrobial Resistance and Implications for the 21st Century. Springer Science & Business Media. ISBN 9780387724188. 
  10. ^ Mendez-Vilas, A. (2011). Science and Technology Against Microbial Pathogens: Research, Development and Evaluation, Proceedings of the International Conference on Antimicrobial Research (ICAR2010), Valladolid, Spain 3 - 5 November 2010. World Scientific. ISBN 9789814354868. 
  11. ^ Ahmad, Iqbal; Aqil, Farrukh (2008-11-21). New Strategies Combating Bacterial Infection. John Wiley & Sons. ISBN 9783527622948. 
  12. ^ Grayson, M. Lindsay; Crowe, Suzanne M.; McCarthy, James S.; Mills, John; Mouton, Johan W.; Norrby, S. Ragnar; Paterson, David L.; Pfaller, Michael A. (2010-10-29). Kucers' The Use of Antibiotics Sixth Edition: A Clinical Review of Antibacterial, Antifungal and Antiviral Drugs. CRC Press. ISBN 9781444147520. 
  13. ^ "Figure 4 : The rise of the Enterococcus: beyond vancomycin resistance : Nature Reviews Microbiology". Retrieved 2015-06-09. 
  14. ^ Meziane-Cherif, Djalal; Saul, Frederick A.; Haouz, Ahmed; Courvalin, Patrice (2012). "Structural and Functional Characterization of VanG d-Ala:d-Ser Ligase Associated with Vancomycin Resistance in Enterococcus faecalis♦". The Journal of Biological Chemistry 287 (45): 37583–37592. doi:10.1074/jbc.M112.405522. ISSN 0021-9258. PMC 3488035. PMID 22969085. 
  15. ^ Coates, Anthony R. M. (2012-08-31). Antibiotic Resistance. Springer Science & Business Media. ISBN 9783642289507. 
  16. ^ McKinnell, James A.; Kunz, Danielle F.; Chamot, Eric; Patel, Mukesh; Shirley, Rhett M.; Moser, Stephen A.; Baddley, John W.; Pappas, Peter G.; Miller, Loren G. (2012). "Association of Vancomycin-Resistant Enterococcus Bacteremia and Ceftriaxone Usage". Infection control and hospital epidemiology : the official journal of the Society of Hospital Epidemiologists of America 33 (7). doi:10.1086/666331. ISSN 0899-823X. PMC 3879097. PMID 22669234. 
  17. ^ Phoenix, David A.; Harris, Frederick; Dennison, Sarah R. (2014-08-25). Novel Antimicrobial Agents and Strategies. John Wiley & Sons. ISBN 9783527676156. 
  18. ^ Balli, Eleni P.; Venetis, Chris A.; Miyakis, Spiros (2014). "Systematic Review and Meta-Analysis of Linezolid versus Daptomycin for Treatment of Vancomycin-Resistant Enterococcal Bacteremia". Antimicrobial Agents and Chemotherapy 58 (2): 734–739. doi:10.1128/AAC.01289-13. ISSN 0066-4804. PMID 24247127. 

Further reading[edit]