Enterococcus bacteria are typically present in the gut and bowel, but they can also live in the mouth and vaginal tract.

At least 58 species of Enteroccoci bacteria exist, but two types tend to infect humans: E. faecalis and E. faecium.

E. faecalis is responsible for approximately 80% of human infections.

Below, learn more about these infections, including prevention, treatment, and antibiotic resistance.

In healthy people, or when the bacteria are present in standard amounts, Enterococci do not usually cause problems.

However, if these bacteria spread to other areas of the body, the infection can be life threatening. In 2017, doctors in the United States reported Enterococci infections in nearly 55,000 people. These infections resulted in 5,400 deaths.

People with a higher risk of E. faecalis infections include those who:

  • are receiving treatment in a hospital
  • have a health condition, such as with HIV or AIDS, that weakens the immune system
  • have open or healing wounds
  • have impaired mobility
  • have a history of urinary tract infections (UTIs)
  • have had a root canal
  • are having cancer treatment
  • are having dialysis
  • are receiving an organ transplant

People in hospitals are particularly vulnerable to E. faecalis infections due to reduced immunity in hospital settings.

The common use of intravascular and urinary catheter devices can also contribute to the spread of infection. E. faecalis can attach to these devices and create a biofilm that allows them to multiply. This is one reason why E. faecalis are a frequent cause of UTIs.

Until 1984, E. faecalis was known as Streptococcus faecalis. Scientists later created the a genus, Enterococcus, to better classify these bacteria.

E. faecalis can cause infection when it enters the body via a wound, blood, or urine.

The symptoms of an E. faecalis infection depend on the location. They can include:

  • fatigue
  • swelling in the gums
  • painful urination
  • stomach cramping
  • vomiting and nausea
  • fever and chills
  • headache
  • diarrhea
  • tachypnea, which is fast, shallow breathing
  • chest pain
  • stiffness in the neck

The location of the infection can determine the diagnosis. For example, doctors may diagnose:

  • bacteremia, which is the medical term for bacteria in the blood
  • an abdominal or pelvic infection
  • a urinary tract infection
  • an oral infection, particularly after a root canal
  • septicemia, which was once called blood poisoning
  • an infection in a wound
  • endocarditis, an infection of the lining of the heart
  • enterococcal meningitis

Bacteria can naturally have resistance to antibiotic treatments. They can also acquire this resistance.

E. faecalis is one of the most antibiotic-resistant types of bacteria, though E. faecium may be even more resistant.

E. faecium bacteria are naturally about 80% resistant to the common antibiotic vancomycin 90% resistant to the antibiotic ampicillin. E. faecalis, on the other hand, are only about 10% resistant to vancomycin, and their primary natural resistance is to ampicillin.

However, higher doses of these antibiotics may still be effective at treating the infection.

However, these bacteria can develop resistance to any other antibiotic, depending on geographic region and the antibiotics in use.

The following factors help E. faecalis resist treatment with antibiotics:

  • Biofilm formation: The bacteria can bind together to form a thin, sturdy layer, known as a biofilm. This can adhere strongly to the surface of, for example, a catheter.
  • Nutritional needs: E. faecalis can endure long periods without a nutritional source. And it can use the serum in human blood as a source of nutrition.
  • Penicillin-binding proteins: These proteins make E. faecalis naturally resistant to penicillin. Penicillin inhibits the activity of E. faecalis, but it does not destroy the bacterial cells.
  • Environmental folic acid absorption: Bacteria require folic acid to grow, and medications that interfere with the production of folic acid can often destroy bacterial infections. But unlike most other types of bacteria, E. faecalis can absorb folic acid from its environment, so these medications have little effect.

The bacteria can also tolerate a variety of conditions. They can survive in a range of temperatures and acidic or alkaline environments.

Due to its natural and acquired antibiotic resistance, treating E. faecalis infections is a significant challenge to healthcare professionals.

The first step is often to take samples of the bacteria from the person with the infection. Healthcare professionals then profile the samples’ susceptibility to various antibiotics, including ampicillin, penicillin, and vancomycin.

A single antibiotic may treat an uncomplicated infection. If no antibiotic resistance is present, ampicillin is the preferred medication.

More severe infections, such as those that cause sepsis, endocarditis, or meningitis, may require a combination of a cell wall-active agent and aminoglycoside.

Cell wall-active agents are antibiotics that target the bacterial cell wall, inhibiting the bacteria’s growth. Examples include ampicillin and vancomycin. Aminoglycosides are a class of antibiotics that includes gentamicin and streptomycin.

Treating a more serious infection can take several weeks.

E. faecalis lives in the gastrointestinal tract, and fecal matter contains it.

Insufficiently cleaning anything that fecal matter touches and not washing the hands after using the bathroom both increase the risk of the bacteria spreading.

Everyday objects, such as phones, doorknobs, towels, and soaps can also contain E. faecalis.

In hospitals, the bacteria can spread due to insufficient hand washing. Insufficiently cleaned tools such as catheters and dialysis ports can also transmit the infection.

Practicing good hygiene, especially in healthcare settings, can help prevent the spread of E. faecalis.

The Centers for Disease Control and Prevention (CDC) suggests these ways to prevent E. faecalis transmission in healthcare settings and more generally:

  • thoroughly washing the hands, including the fingertips and thumbs, after using the bathroom
  • washing the hands before eating or drinking
  • washing the hands after any contact with pets or livestock
  • not sharing personal hygiene items, such as soaps, washcloths, towels, and razors
  • regularly cleaning bathrooms, especially toilets
  • avoiding any toilets that seem unclean
  • disinfecting doorknobs, remote controls, telephones, and other commonly shared objects
  • frequently washing the hands — for hospital patients, staff, and visitors
  • ensuring that medical professionals wash their hands before contact with IV lines, catheters, and dressings
  • ensuring that medical professionals wash their hands between patients
  • not sitting on the beds of other patients
  • avoiding the toilets of other patients

Learn the most effective way to wash the hands here.

Meanwhile, anyone taking antibiotics for an E. faecalis infection might consider taking probiotics to prevent the infection from returning.

Long-term antibiotic use can promote the colonization of harmful bacteria, such as E. faecalis, in the digestive tract. This is because these medications reduce the diversity of helpful bacteria.

Research shows that consuming probiotics after taking antibiotics may help replenish populations of helpful bacteria in the gut, restoring a balance that helps reduce the risk of the infection recurring.

Enterococcal infections often develop in people with health conditions, particularly those that require hospital treatment. This can make it difficult to determine the role that the bacteria play in any worsening or subsequent illness or death.

Some research suggests that the outlook for people with E. faecalis infections is linked to their overall health status, not the presence of the bacteria.

Infections caused by antibiotic-resistant bacteria, such as E. faecalis, tend to result in longer hospital stays, higher healthcare costs, and higher mortality rates, compared with infections stemming from bacteria without this resistance.

Good hygiene practices are the best ways to prevent infection with E. faecalis.