Enterococcal Infection - Causes, Symptoms, and Treatment

Introduction:

Enterococci are naturally occurring bacteria in the intestines of humans and animals. They were previously classified as group D streptococci before being assigned their own genus. Although more than 17 species are in the genus Enterococcus, only a few cause infections in humans. Enterococcus species can survive temperatures as high as 60 degrees Celcius for short durations and grow in high salt concentrations. They are increasingly identified as major human pathogens, posing significant therapeutic challenges, such as the need for synergistic antibiotic combinations to successfully treat enterococcal infective endocarditis (IE).

The most common species cultured from humans are Enterococcus faecalis and Enterococcus faecium, which account for more than 90 percent of clinical isolates. Enterococcus avium, Enterococcus casseliflavus, Enterococcus raffinosus, Enterococcus gallinarum, Enterococcus durans, and Enterococcus mundtii are among the other enterococcal species known to be pathogenic to humans. Although Enterococcus faecalis is more virulent or pathogenic and is responsible for roughly 80 percent of human infections, E faecium causes the majority of vancomycin-resistant enterococci (VRE) infections.

Who Are At Risk Of The Disease?

• Enterococci are usually not pathogenic in healthy people or when the bacteria are present in normal amounts. However, the infection can be deadly if these bacteria spread to other body parts. Nearly 55,000 people in the United States were diagnosed with Enterococci in 2017. These infections also resulted in the death of 5,400 people.

• Enterococcal infections are more common in older adults as several associated factors, like urinary tract catheterization and instrumentation, are more common in the elderly population. In addition, abdominal surgery for diverticulitis or biliary tract disease is also more common among older adults. In a recent study, most cases of enterococcal endocarditis were observed in the elderly.

• Enterococci can cause bacteremia and meningitis in newborns. Outbreaks of enterococcal infections, including VRE infections, in newborns, have been reported. However, VRE infections are less common in pediatric patients than in adults.

What Causes Enterococcal Infections?

Infections caused by enterococci spread from person to person due to poor hygiene. Because these bacteria are found in the intestine and spread through feces, people who do not wash their hands after using the restroom can spread the infection. In addition, bacteria can enter the food or settle on surfaces such as doorknobs, phones, and computer keyboards. They may then pass on to other people.

Enterococci are frequently spread in hospital settings. For example, healthcare workers can spread the infection if they do not wash their hands between patients or after touching contaminated surfaces. In addition, Enterococci can be found in improperly cleaned catheters, dialysis ports, and other medical devices. As a result, people with an organ transplant, kidney dialysis, or cancer treatment are more likely to develop infections due to immune suppression or contamination through their catheters.

What Are The Symptoms Of An Enterococcal Infection?

Symptoms of Enterococcal infection can vary depending on the type of infection. They may include the following:

• Fever.

• Chills.

• Nausea.

• Vomiting.

• Diarrhea.

• Headache.

• Abdominal pain.

• Pain or burning when urinating.

• Rapid breathing or shortness of breath.

• Stiff neck.

• Fatigue.

• Bleeding gums.

What Do Enterococcal Infections Cause?

Urinary tract infections (UTIs), endocarditis, bacteremia, catheter-related infections, wound infections, and intra-abdominal and pelvic infections are all common infections caused by enterococci. Many infecting strains commence from the patient's gut flora. They can spread from here and cause UTI, intra-abdominal infection, and surgical wound infection.

Urinary Tract Infection: It is an infection that involves any part of the urinary system, including the kidneys, bladder, uterus, and urethra. Women are more at risk of a UTI than men. The symptoms include;

• A persistent and strong urge to urinate.

• A burning sensation when urinating.

• Passing only small amounts of urine.

• Cloudy, red, pink, or cola-colored urine.

• Lower abdominal pain.

Bacteremia: Bacteremia occurs when a bacterial infection enters the bloodstream. Bacteremia can be caused by various infections, including those caused by Enterococcus, such as urinary tract infections or wound infections. The symptoms of bacteremia include;

• Chills and fever.

• Vomiting and nausea.

• Appetite loss.

• Breathing difficulties.

• Rapid heart rate.

• Lightheadedness.

• Rashes on the skin.

• Disorientation or loss of consciousness.

Wound Infection: It occurs when cuts, scratches, animal bites, sutured wounds, and open wounds become infected 24 to 72 hours after the event. Wound infection symptoms include;

• Pus.

• A spreading red area or streak.

• Increased pain and swelling.

• High fever.

• A swollen lymph node.

E. faecalis wound infections are more challenging to treat than other types of bacteria.

Endocarditis: Endocarditis, also known as heart valve infection, occurs when bacteria enter the bloodstream and attach to the heart's inner lining and the surfaces of its valves. ‌Endocarditis symptoms include:

• Flu-like symptoms include fever, achiness, chills, or night sweats.

• A new heart murmur.

• Tiny bumps on the skin of the hands or feet.

• Spots on the whites of the eyes or roof of the mouth.

How Are Enterococcal Infections Treated?

Enterococci involved with endocarditis are challenging to eradicate unless the bactericidal activity is achieved by combining certain cell wall-active drugs (e.g., Penicillin, Ampicillin, Amoxicillin, Piperacillin, Vancomycin) with an aminoglycoside (e.g., Gentamicin, Streptomycin). However, some cell wall-active drugs, such as Nafcillin, Oxacillin, Ticarcillin, Ertapenem, most Cephalosporins, and Aztreonam, have limited or no activity against enterococci.

Penicillin resistance is higher in E. faecium than in E. faecalis. Therefore, when an aminoglycoside is not an option, a combination of Aminopenicillin, such as Ampicillin and Ceftriaxone, is an effective treatment for E. faecalis endocarditis. Imipenem and, to a lesser extent, Meropenem are anti-E. faecalis.

UTIs are usually far more manageable. The doctor will likely only need to prescribe one antibiotic, such as Ampicillin. Vancomycin-resistant enterococcal urinary tract infection is frequently treated with nitrofurantoin and fosfomycin.

Daptomycin, Linezolid, Tigecycline, and Omadacycline are effective treatments for complicated skin infections caused by vancomycin-susceptible enterococci. Piperacillin or Tazobactam, Imipenem or Meropenem, and Eravacycline are preferred for complicated intra-abdominal infections involving enterococci.

Conclusion:

Enterococci are naturally occurring bacteria in the intestines of humans and animals. Enterococcus faecalis and Enterococcus faecium account for more than 90 percent of human infections. They are often through contaminated surfaces. Enterococcus infections are challenging to treat since the bacteria are resistant to several antibiotics. One effective treatment method involves combining a wall-active drug with an aminoglycoside. On the other hand, skin infections and endocarditis frequently necessitate different combinations. UTIs are usually far more manageable and only need one antibiotic, such as Ampicillin.