''Enterococcus faecium'' is a

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

, gamma-hemolytic or non-

hemolytic Hemolysis or haemolysis (), also known by several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo o ...

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were amon ...

in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Enterococcus ''Enterococcus'' is a large genus of lactic acid bacteria of the phylum Bacillota. Enterococci are gram-positive cocci that often occur in pairs (diplococci) or short chains, and are difficult to distinguish from streptococci on physical char ...

''. It can be

commensal Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...

(innocuous, coexisting organism) in the gastrointestinal tract of humans and animals, but it may also be

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

ic, causing diseases such as neonatal meningitis or

endocarditis Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves. Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or the ...

Vancomycin Vancomycin is a glycopeptide antibiotic medication used to treat a number of bacterial infections. It is recommended intravenously as a treatment for complicated skin infections, bloodstream infections, endocarditis, bone and joint infections, ...

-resistant ''E. faecium'' is often referred to as VRE.

Pathogenic properties

This bacterium has developed multi-drug antibiotic resistance and uses colonization and secreted

factors Factor, a Latin word meaning "who/which acts", may refer to: Commerce * Factor (agent), a person who acts for, notably a mercantile and colonial agent * Factor (Scotland), a person or firm managing a Scottish estate * Factors of production, su ...

in virulence (enzymes capable of breaking down fibrin, protein and carbohydrates to regulate adherence bacteria to inhibit competitive bacteria). The enterococcal surface protein (Esp) allows the bacteria to aggregate and form biofilms. 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. By producing the enterocins A, B, and P (genus-specific

bacteriocins Bacteriocins are proteinaceous or peptidic toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s). They are similar to yeast and paramecium killing factors, and are structurally, functionally, and ec ...

), ''Enterococcus faecium'' can combat pathogenic gut microbes, such as ''

Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esc ...

,'' reducing gastrointestinal disease in hosts. As an alternative to adding antibiotics to livestock feed, which risks

antimicrobial resistance Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistance. P ...

, ''E. faecium'' Strain NCIMB 10415 is being used as a probiotic in animal feed. However, the constant exposure to high levels of this microbe result in immunosuppression by reducing expression of IL-8, IL-10, and

CD86 Cluster of Differentiation 86 (also known as CD86 and B7-2) is a protein constitutively expressed on dendritic cells, Langerhans cells, macrophages, B-cells (including memory B-cells), and on other antigen-presenting cells. Along with CD80, CD8 ...

, predisposing livestock to severe '' Salmonella'' infections.

Vancomycin-resistant ''Enterococci'' (VRE)

''Enterococcus faecium'' has been a leading cause of multi-drug resistant enterococcal infections over ''

Enterococcus faecalis ''Enterococcus faecalis'' – formerly classified as part of the group D ''Streptococcus'' system – is a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans. Like other species in the genus ''Enterococcus'', ''E ...

'' in the United States. Approximately 40% of medical intensive care units reportedly found that the majority, respectively 80% and 90.4%, of device-associated infections (namely, infections due to central lines, urinary drainage catheters, and ventilators) were due to vancomycin- and ampicillin-resistant ''E. faecium.'' The rapid increase of VRE has made it difficult for physicians to fight infections caused by ''E. faecium'' since not many antimicrobial solutions are available. In the United States infections by VRE occurs more frequently. Persons infected or colonized with VRE are more likely to transmit the organism. Transmission depends primarily on which body site(s) harbor the bacteria, whether the body fluids are excreted and how frequently health care providers touch these body sites. Patients infected or colonized with VRE may be cared for in any patient care setting with minimal risk of transmission to other patients provided appropriate infection control measures are taken. A genome-wide ''E. faecium'' sRNA study suggested that some sRNAs are linked to the antibiotic resistance and stress response.

VRE symptoms

''Enterococcus'' infections, including VRE infections, cause a range of different symptoms depending on the location of the infection. This includes infections of the bloodstream, urinary tract infections (UTI), and wound infections associated with catheters or surgery. Wound infections associated with catheters and surgery can cause soreness and swelling at wound site, red, warm skin around wounds, and fluid leakage. Urinary tract infections can cause frequent or intense urges to urinate, pain or burning sensations while urinating, fatigue, and lower back or abdominal pain. Bloodstream infections can cause fever, chills, body aches, nausea and vomiting, and diarrhea.

Genome sequences

The 22 sequenced ''Enterococcus faecium'' genomes:

Tolerance to alcohol-based disinfectants

A study published in 2018 showed multi drug-resistant ''E. faecium'' exhibiting tolerance to alcohol-based solutions. The authors speculated about this being an explanation to an increase of ''E. faecium'' infections, indicating that alternate methods are required to slow the spread of ''E. faecium'' in a hospital setting. The study found that isolates of the bacterium from after 2010 were 10 times more tolerant of the alcohol-based disinfectants than older isolates. However, the isopropanol solutions tested in this study used isopropanol concentrations lower than those used in most hand disinfectants and the authors also stated that hand disinfectants using 70% isopropanol were effective in full strength even against tolerant strains. However, a mouse gut colonization model of ''E. faecium'' transmission showed that alcohol-tolerant ''E. faecium'' resisted standard 70% isopropanol surface disinfection, resulting in greater mouse gut colonization compared to alcohol-sensitive ''E. faecium.'' This research has led some to question whether it may be possible for microbes to become entirely tolerant of alcohol.

Treatment

Linezolid Linezolid is an antibiotic used for the treatment of infections caused by Gram-positive bacteria that are resistant to other antibiotics. Linezolid is active against most Gram-positive bacteria that cause disease, including streptococci, v ...

daptomycin Daptomycin, sold under the brand name Cubicin among others, is a lipopeptide antibiotic used in the treatment of systemic and life-threatening infections caused by Gram-positive organisms. Daptomycin was removed from the World Health Organiza ...

tigecycline Tigecycline, sold under the brand name Tygacil, is an tetracycline antibiotic medication for a number of bacterial infections. It is a glycylcycline administered intravenously. It was developed in response to the growing rate of antibiotic resist ...

and the streptogramins (e.g.

quinupristin/dalfopristin Quinupristin/dalfopristin, or quinupristin-dalfopristin, (pronunciation: kwi NYOO pris tin / dal FOE pris tin) (trade name Synercid) is a combination of two antibiotics used to treat infections by staphylococci and by vancomycin-resistant '' Ente ...

) can have activity against VRE. VRE can be successfully treated with

sultamicillin Sultamicillin, sold under the brand name Unasyn among others, is an oral form of the penicillin antibiotic combination ampicillin/sulbactam. It is used for the treatment of bacterial infections of the upper and lower respiratory tract, the kidneys ...

References

External links

Type strain of ''Enterococcus faecium'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q140010 faecium Bacteria described in 1984