Enterococcus faecium
Enterococcus faecium is a naturally occurring gram-positive in the intestine of humans and animals bacterium. Catalase -negative enterococci are often arranged in pairs or in the form of chain. There are undemanding organisms that also have both an anaerobic and aerobic metabolism. The relationship with Enterococcus faecalis is very tight, but E. faecium has some clinically relevant properties that make it different from E. faecalis.
Proof
On blood agar you can mostly observe no hemolysis or γ - hemolysis. Enterococcus faecium is just like its close relative Enterococcus faecalis largely resistant to bile salts and optochin. It is heat stable (growth at 45 ° C ) and salt tolerant (growth in 6.5 % NaCl solution). They also hydrolyze esculin. They carry the Lancefield group D antigen, but the extraction of the antigen is more difficult than for the streptococci, enterococci as this antigen is based on a non- cell wall bound teichoic acid, which acts as a carbon material.
Clinical Significance
The occurrence in the intestine alone has no clinical significance when antibiotics are given, E. faecium may be the development of resistance to the main germ of the intestinal flora. So far, no toxins and few other virulent factors could be detected, for example, an aggregation substance.
The pathogenic strains cause nosocomial infections in people with weakened immune systems. Furthermore, endocarditis, and cholecystitis, cystitis and pressure ulcers can occur with E. faecium. Complications such as urosepsis or peritonitis are often difficult treatable because of the resistance of the pathogen. In total there is E. faecium infections as rare in E. faecalis, vancomycin -resistant Enterococcus is terrible ( faecium ) ( AER) one of the most difficult to treat type germs at all.
Living germs of strain Cernelle 68 (SF 68) from Enterococcus faecium are offered for the treatment of diarrheal diseases and rebuild the intestinal flora in the form of capsules.
Resistance
Natural resistance are due to all cephalosporins, macrolides, fusidic acid and sulphonamides. Furthermore, the great majority of isolates ( 90 %) resistant against ampicillin and amoxicillin. This resistance is typically non-enzymatically mediated by β -lactamases, but by mutations or overexpression of the penicillin binding protein 5, Therefore, it can not be overcome by adding a β -lactamase inhibitor usually.
Treatment
By Enterococcus faecium infections caused are relatively difficult to treat with antibiotics, since only a few antibiotics are contemplated. The standard treatment can still be considered vancomycin, and this (see above) is at AER basically ineffective. As alternatives, teicoplanin, linezolid and tigecycline may be considered, in uncomplicated urinary tract infections ( which are however rarely caused by E. faecium ) may also fosfomycin or nitrofurantoin.
In a study with mice, the colonization with vancomycin - resistant E. faecium could be prevented by implantation with bacteria of the species Barnesiella and undone.