Vancomycin-resistant Enterococcus

From MicrobeWiki, the student-edited microbiology resource


SEM of Vancomycin-resistant Enterococcus.

By [Evan Baum]

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Enterococci are a group of bacterial that are rod-shape, gram positive bacteria that can live within the digestive tract of humans. There, the aid in the digestion of food, but cause infections in other places of the body. Enterococci are very resilient organisms, the can be found not only in intestinal tract but in soil, water, and food. They are able to live in temperatures ranging from 10-45 C and pH ranges from 4.8 to 9.6. Vancomycin-resistant Entercoccus (VRE) is a bacterial strain of Enterococcus that has acquired resistance to the antibiotic vancomycin through the uptake of a plasmid that has the resistance . VRE is a major concern to hospitals. Healthcare workers can carry the bacteria and pass it along to patients. VRE is most associated with nosocomial infections, making up about 30% of all enterococcus infections in hospitals. Healthy people can bring VRE into the hospital where it can then infect patients. This bacteria is very dangerous towards immunocompromised individuals. With VRE's aptitude for passing on it's genes to other bacteria, this strain is very capable of transferring it's resistance to lethal infections such as MRSA.

Acquired vancomycin resistance

Depiction of Vancomycin sensitive and vancomycin resistant bacteria from Mcstrother.

Vancomycin resistant Enterococcus was isolated in Europe in the late 1980s. However the use of Vancomycin began clinical use in the 1950s but was not wide spread until 1970s. Vancomycin works by inhibiting cell wall formation in gram positive bacteria and by this mechanism, is the reason why vancomycin does not work with gram negative bacteria. Between each cell wall is a chain of amino acids that a cross linking enzyme recognizes and connects the carbohydrate chains. Vancomycin recognizes the two D alanine at the top of each chain and binds to them. The cross-linking enzyme can then not work properly and the cell wall would not from. For resistant bacteria, instead of have two D-alanine the last D-alanine has been replaced with D-lactate. This does not allow for vancomycin to bind properly and lets the cross-linking enzyme to properly form the cross links.

A vancomycin resistant bacteria sharing vanB gene with a vancomycin sensitive bacteria from the CDC.

There are three types of clinically studied vancomycin resistant genes, vanA, vanB, and vanC. The highest resistance to vancomycin is vanA and continues decreasing with vanB then vanC. While vanB is still highly resistant to vancoymcin it is highly susceptible to teicoplanin. The last operon, vanC, has very low resistance to vancomycin and teicoplanin but this property is not transferable to other species. The resistance is transferred through a plasmid from an already resistant bacteria to a sensitive bacteria. Due to enterococcus nature to be able to

Happens in hospitals

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prevention and treatment

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[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by student of Joan Slonczewski for BIOL 238 Microbiology, 2011, Kenyon College.