Enterococcus faecium: Difference between revisions

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==Pathology==
==Pathology==
How does this organism cause disease?  Human, animal, plant hosts?  Virulence factors, as well as patient symptoms.
E. faecium is considered a super-bug. It can colonize many organs of the body including the gastrointestinal tract and the skin, and can also survive for long periods on inanimate objects. This along with its multi-drug resistant characteristics makes it a particularly nasty pathogen.
 
Contributing to the virulence of E. faecium is the enterococcal surface protein (Esp). This protein allows the bacteria to aggregate and form bioflims. Strains with the Esp gene are normally found in clinical isolates and not found in strains that colonize the gut. Bioflim formation allows colonization of tubing used in hospitals and can lead to infections of the blood as well as urinary tract infections. Esp gene expression increased under increased temperature as well as a change to anaerobic condition. The regulation of the Esp gene in this way allows E. faecium to change its response when it enters a host. (6)
 
Additional virulence factors include aggregation substance (AS), cytosolin, and gelantinase. AS allows the microbe to bind to target cells and it facilitates the transfer of genetic material between cells. Cytosolin is a protein found in the cytosol and lyses erythrocytes. GeIE can hydrolyze peptides. The presence of virulence factors differ among strains and usually are specific for the host the strain colonizes. (9)


==Application to Biotechnology==
==Application to Biotechnology==

Revision as of 19:48, 4 June 2007

A Microbial Biorealm page on the genus Enterococcus faecium

Classification

Higher order taxa

Domain: Bacteria; Phylum Firmicutes; Class: Bacilli; Order: Lactobacillales; Family: Enterococcus(1)

Species

NCBI: Taxonomy

Enterococcus faecium(2)

Description and significance

E. faecium is a human pathogen that causes nosocomial bacteremia, surgical wound infection, endocarditis, and urinary tract infections. Nosocomial infections are those acquired in medial setting during treatment of a prior complaint. The normal habitat includes the gastrointestinal tract of a multitude of animals but it can also be found in the oral cavity and vaginal tract.(3) The microbe can survive for long periods of time in soil, sewage, and inside hospitals on a variety of surfaces.(6) It can grow in temperatures ranging from 10 to 45 degrees Celsius, in basic or acidic environments, and in environments which are isotonic or hypertonic.(3)

E. faecium is a Gram-positive, spherical cell that can occur in pairs or chains. The colonies formed are 1-2 mm in length and appear wet. The cells are non-motile. (8)

E. faecium is highly drug resistant and acquires its drug resistance by plasmids and conjugative transposons as well as chromosomal genes that encode resistance. Some strains have become resistant to vancomycin, penicillin, gentamicin, tetracycline, erythromycin and teicoplanin. Spread of the disease occurs between patients in hospitals due to transfer of the pathogen by hands or medical instruments. Also antibiotic use can decrease the number of other intestinal bacteria that are susceptible to the antibiotic and decrease competition for the drug resistant E. faecium. (3)

E. faecium was known as Streptococcus faecium until its name changed in 1984 due to a re-categorization. (2)

Genome structure

The sequencing of a vacomycin resistant E. faecium strain, Enterococcus faecium V583, revealed 1 circular chromosome and 3 plasmids. The chromosome consists of 3218031 base pairs and each plasmid, pTEF1, pTEF2, pTEF3, consists of 66320, 57660, and 17963 base pairs respectively.

Two of the plasmids are pheromone-sensing conjugative plasmids. Also found was a mobile conjugative transposon that encodes vacomycin resistance. Over a quarter of E. faecium’s 3337 open reading frames are mobile and/or exogenously acquired DNA. These mobile and/or exogenously acquired DNA include seven integrated phage regions, 38 insertion elements, conjugative and composite transposons, a patheogenicity island, and integrated plasma genes. Its ability to acquire outside DNA contributes to E. faecium’s multiple drug resistance. The genes encoding vacomycin resistance in E. faecium’s are similar to E. faecalis’ vanB vancomycin-resistance conjugative transposon Tn1549 and were probably transferred as a cassette by lateral gene transfer. (5)

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Ecology

E. faecium can acquire drug resistance through three types of conjugation: pheromone-responsive plasmids, broad host-range plasmids, and conjugative transposons. Pheromone response plasmid occurs when the cell secretes a sex pheromone for a specific plasmid. When a donor cell comes into contact with the pheromone, transcription of the relevant portion of the plasmid is turned on and is also secretes a sticky substance. The sticky or aggregation substance facilitates the transfer of the plasmid to the recipient cell by helping them to stick together. Transfer of other plasmids can also occur between different genera of bacteria including staphylococci, and streptococci. The consequence of the ability of E. faecium to acquire broad host-range plasmids is that drug resistance can be widely and more easily spread. Conjugative transposons can also transfer antibiotic resistance between genera as well as between gram-positive and gram-negative bacteria because they do not need to cooperate with host machinery in order to insert themselves into a plasmid or chromosome of the bacterium. E. faecium can interact with other bacteria to spread drug resistance through conjugation. (4)

Pathology

E. faecium is considered a super-bug. It can colonize many organs of the body including the gastrointestinal tract and the skin, and can also survive for long periods on inanimate objects. This along with its multi-drug resistant characteristics makes it a particularly nasty pathogen.

Contributing to the virulence of E. faecium is the enterococcal surface protein (Esp). This protein allows the bacteria to aggregate and form bioflims. Strains with the Esp gene are normally found in clinical isolates and not found in strains that colonize the gut. Bioflim formation allows colonization of tubing used in hospitals and can lead to infections of the blood as well as urinary tract infections. Esp gene expression increased under increased temperature as well as a change to anaerobic condition. The regulation of the Esp gene in this way allows E. faecium to change its response when it enters a host. (6)

Additional virulence factors include aggregation substance (AS), cytosolin, and gelantinase. AS allows the microbe to bind to target cells and it facilitates the transfer of genetic material between cells. Cytosolin is a protein found in the cytosol and lyses erythrocytes. GeIE can hydrolyze peptides. The presence of virulence factors differ among strains and usually are specific for the host the strain colonizes. (9)

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research here--at least three required

References

1. Skerman, V.B.D., McGowan, V., and Sneath, P.H.A. (editors): "Approved lists of bacterial names." Int. J. Syst. Bacteriol. (1980) 30:225-420. Schleifer KH & Kilpper-Balz R (1984) 2. Schleifer, K.H., and 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. nov." Int. J. Syst. Bacteriol. (1984) 34:31-34.


Edited by Morgan Feori