Enterococci play a significant role in the intestinal flora and, correspondingly, in the immune system. However, nosocomial (hospital-acquired) infectious diseases are in many cases traceable to enterococcal strains.
What are enterococci?
Enterococci is the name given to a distinct genus of gram-positive lactic acid bacteria with a spherical (coccoid) morphology that belongs to the Streptococcaceae family. Microscopically, they mostly form short chains or are arranged in pairs. Enterococci, particularly the strains Enterococcus faecalis and Enterococcus faecium, are physiologically found in the intestinal flora of humans and animals, where they are thought to play a supporting role in digestion. Enterococci can infect the urogenital tract (urinary and genital tract) via smear infection and cause urinary tract infections and inflammation of the fallopian tubes. In general, the enterococcal strains Enterococcus durans, Enterococcus avium, Enterococcus faecalis, Enterococcus faecium, Enterococcus gallinarum, and Enterococcus solitarius are differentiated as the most important representatives of the more than 30 known species.
Significance and function
The healthy intestinal flora is colonized by up to 200 intestinal bacteria and as many fungi, which keep each other in balance so that no pathogenic colonization can take place. The intestinal flora accordingly plays a supporting role for the immune system and also regulates the synthesis of essential vitamins. Of particular physiological importance for the digestive system are the Enterococcus faecalis and Enterococcus faecium strains, which are able to survive in the intestinal tract due to their resistance (insensitivity to high and low pH and to bile). Enterococcus species such as Enterococcus faecalis and Enterococcus faecium are furthermore found not only in the intestinal flora but also in breast milk. As a result, the digestive tract of the nursing child is supplied with physiologically important microorganisms postnatally and can gradually build up a healthy intestinal flora, which at the same time protects the child’s organism from pathogenic germs. Enterococci also ensure an acidic environment in their environment, which in turn inhibits the growth of a large number of pathogenic germs that require a higher pH value for cell division. As a result of these positive characteristics, enterococci are used in dairy products such as yogurts, goat cheese, raw sausages or camemberts as probiotic fermentation agents to protect against pathogenic microorganisms and to build up the intestinal flora. Especially following antibiotic therapies, during which not only the infection-causing bacteria but also the physiologically important bacteria of the intestinal flora are killed, enterococci can be used as probiotics (especially Enterococcus faecalis ) prophylactically to protect against diarrhea and thus against increased fluid loss.
Diseases
However, as facultative pathogens, enterococci can cause discomfort and infection when they exit the intestine with subsequent colonization of adjacent structures. Enterococcus faecalis as well as Enterococcus faecium have been implicated in a number of nosocomial-related illnesses. In particular, urinary tract infections, septic infections, endo- and peritonitis (inflammation of the inner lining of the heart and peritoneum) as well as intra-abdominal abscesses, wound infections and catheter-associated infections are prominent in this context. Urinary tract infections are in most cases due to bacterial colonization of the urinary tract. This is particularly true for women, as the urethral and intestinal openings are comparatively close together in women. In addition, due to the shorter urethra, women are at increased risk of infection spreading to the urinary bladder (cystitis). In particular, people with a weakened immune system as a result of HIV infection, chemotherapeutic, antibacterial and/or immunosuppressive therapy, as well as those with an underlying disease with a severe course or who have undergone cardiac or thoracic surgery, have an increased risk of contracting nosocomial enterococcal infections.It is estimated that up to 15 percent of endocarditis and about 30 percent of septic infections in adults can be attributed to enterococci, while acute urinary tract infections are associated with enterococci in 10 to 20 percent of cases. In particular, infections with the so-called vancomycin-resistant enterococci (VRE) can be lethal in cancer patients receiving chemotherapy. Vancomycin-resistant enterococci are also the most common cause of bacteremia following antibiotic treatment. In rare cases, primarily the Enterococcus faecalis and Enterococcus faecium strains can cause (ventilator-associated) enterococcal pneumonia, a pneumonia with a mostly subacute course. In addition, enterococci are often involved in mixed infections such as cholecystitis (gallbladder inflammation).