Enterococcus faecium in vaginal infections

Enterococcus faecium is a gram-positive biofilm-forming aerobic pathogenic bacteria that can cause or contribute to urinary tract infections and vaginal infections in women, while also being a problematic hospital-acquired infection. 

E. faecium normally lives in the digestive tract of animals and humans, but is found in the mouth and vagina too, being considered a super-bug.

E. faecium can survive away from a host for long periods of time – on skin, in soil, sewage, and on hospital surfaces. Growing temperatures range from 10-45C, in acidic or alkaline pH conditions, and in the presence of moisture or dryness. 

E. faecium is not able to move by itself, so must be transported (non-motile) by hands, tools, etc. This means E. faecium can be sexually transmitted, but by skin-to-skin contact, not necessarily just body fluids.

E. faecium obtains its energy from fermentation if oxygen is not present, making it a facultative bacteria – that means it’s got two ways of making energy and can adapt to its environment. A recategorisation in 1984 saw E. faecium’s name changed from Streptococcus faecium. A close relative of E. faecium is Enterococcus faecalis.

Antibiotic resistance of E. faecium

E. faecium is known to be highly antibiotic resistant, with some strains having known resistance to:

• Vancomycin
• Penicillin
• Gentamicin
• Tetracycline
• Erythromycin
• Teicoplanin

An issue with antibiotic use in E. faecium infections is the way antibiotics kill off susceptible bacteria and reduce competition for drug-resistant E. faecium.

How bad is E. faecium?

A protein on the surface of the bacteria allows E. faecium to form biofilms and change into an anaerobe, with a special gene responsible that is sometimes on and sometimes off, depending on its situation. E. faecium binds to cells and provides the mechanism for the transfer of genetic material between cells. The presence of certain characteristics differs amongst strains, and tend to be specific to its environment.

E. faecium produces bacteriocins, which are antibacterial substances that kill or maim other bacteria, used as a bacterial weapon to maintain dominance. These weapons are what makes E. faecium a good bacteria for use in fermentation of cheese and vegetables, because it keeps other microbes out in a very efficient way.

In some medical uses, E. faecium can be used in the digestive tract to out-compete other bacteria. It is this ability that makes E. faecium a problematic vaginal bacteria, because it out-competes lactobacilli.

As E. faecium goes through its life cycle (eating, fighting, excreting, dying), it is known to cause cell DNA damage, producing superoxide, hydrogen peroxide, and hydroxyl radicals, which can cause polyps or colon cancer.

Hydrogen peroxide from E. faecium has been demonstrated to damage colonic cells in animal studies – E. faecium can be a carcinogen.