Enterococcus is a large genus of lactic acid bacteria of the phylum Bacillota. Enterococci are gram-positive cocci that often occur in pairs (diplococci) or short chains, and are difficult to distinguish from streptococci on physical characteristics alone. Two species are common commensal organisms in the intestines of humans: E. faecalis (90–95%) and E. faecium (5–10%). Rare clusters of infections occur with other species, including E. casseliflavus, E. gallinarum, and E. raffinosus.
Bloodstream infections (BSIs) are infections of blood caused by blood-borne pathogens. Blood is normally a sterile environment, so the detection of microbes in the blood is always abnormal. A bloodstream infection is different from sepsis, which is characterized by severe inflammatory or immune responses of the host organism to pathogens.
Vancomycin-resistant Staphylococcus aureus (VRSA) are strains of Staphylococcus aureus that have acquired resistance to the glycopeptide antibiotic vancomycin. Bacteria can acquire resistant genes either by random mutation or through the transfer of DNA from one bacterium to another. Resistance genes interfere with the normal antibiotic function and allow a bacteria to grow in the presence of the antibiotic. Resistance in VRSA is conferred by the plasmid-mediated vanA gene and operon. Although VRSA infections are uncommon, VRSA is often resistant to other types of antibiotics and a potential threat to public health because treatment options are limited. VRSA is resistant to many of the standard drugs used to treat S. aureus infections. Furthermore, resistance can be transferred from one bacterium to another.
Staphylococcus lugdunensis is a coagulase-negative member of the genus Staphylococcus, consisting of Gram-positive bacteria with spherical cells that appear in clusters.
Vancomycin-resistant Enterococcus, or vancomycin-resistant enterococci (VRE), are bacterial strains of the genus Enterococcus that are resistant to the antibiotic vancomycin.
Enterococcus faecalis – formerly classified as part of the group D Streptococcus system – is a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans. Like other species in the genus Enterococcus, E. faecalis is found in healthy humans and can be used as a probiotic. The probiotic strains such as Symbioflor1 and EF-2001 are characterized by the lack of specific genes related to drug resistance and pathogenesis. As an opportunistic pathogen, E. faecalis can cause life-threatening infections, especially in the nosocomial (hospital) environment, where the naturally high levels of antibiotic resistance found in E. faecalis contribute to its pathogenicity. E. faecalis has been frequently found in reinfected, root canal-treated teeth in prevalence values ranging from 30% to 90% of the cases. Re-infected root canal-treated teeth are about nine times more likely to harbor E. faecalis than cases of primary infections.
Streptococcus bovis is a species of Gram-positive bacteria that in humans is associated with urinary tract infections, endocarditis, sepsis, and colorectal cancer. S. gallolyticus is commonly found in the alimentary tract of cattle, sheep, and other ruminants, and may cause ruminal acidosis or feedlot bloat. It is also associated with spontaneous bacterial peritonitis, a frequent complication occurring in patients affected by cirrhosis. Equivalence with Streptococcus equinus has been contested.
Oritavancin, sold under the brand name Orbactiv among others, is a semisynthetic glycopeptide antibiotic medication for the treatment of serious Gram-positive bacterial infections. Its chemical structure as a lipoglycopeptide is similar to vancomycin.
Delftia acidovorans is a Gram-negative, motile, non-sporulating, rod-shaped bacterium known for its ability to biomineralize gold and bioremediation characteristics. It was first isolated from soil in Delft, Netherlands. The bacterium was originally categorized as Pseudomonas acidovorans and Comamonas acidovorans before being reclassified as Delftia acidovorans.
Enterococcus faecium is a Gram-positive, gamma-hemolytic or non-hemolytic bacterium in the genus Enterococcus. It can be commensal in the gastrointestinal tract of humans and animals, but it may also be pathogenic, causing diseases such as neonatal meningitis or endocarditis.
Enterococcus durans is a species of Enterococcus. It is a gram-positive, catalase- and oxidase-negative, coccus bacterium. The organism is also a facultative anaerobic organism. Prior to 1984, it was known as Streptococcus durans.
Enterococcus gallinarum is a species of Enterococcus. E. gallinarum demonstrates an inherent, low-level resistance to vancomycin. Resistance is due to a chromosomal gene, vanC, which encodes for a terminal D-alanine-D-serine instead of the usual D-alanine-D-alanine in cell wall peptidoglycan precursor proteins. That is a separate mechanism than the vancomycin resistance seen in VRE isolates of E. faecium and E. faecalis which is mediated by vanA or vanB. This species is known to cause clusters of infection, although it considered very rare. It is the only other known enterococcal species besides E. faecium and E. faecalis known to cause outbreaks and spread in hospitals.
Grimontia hollisae is a species of Grimontia proteobacteria found naturally in marine environments. Based on phylogenetic evidence, the species was reclassified in 2003 from Vibrio hollisae.
Staphylococcus gallinarum is a Gram-positive, coagulase-negative member of the bacterial genus Staphylococcus consisting of single, paired, and clustered cocci. Strains of this species were first isolated from chickens and a pheasant. The cells contain cell walls with chemical similarity to those of Staphylococcus epidermidis. Since its initial discovery, S. gallinarum has also been found in the saliva of healthy human adults.
D-Alanine—D-serine ligase is an enzyme with systematic name D-alanine:D-serine ligase (ADP-forming). This enzyme catalyses the following chemical reaction
Enterococcus hirae is a species of Enterococcus. Its type strain is NCDO 1258. It is involved in growth depression in young chickens and endocarditis and sepsis in humans.
Enterococcus malodoratus is a species of the genus Enterococcus and a gram positive bacteria capable of opportunistic pathogenic response. These microbes have a thick polypeptide layer. Enterococcus can be found in the gastrointestinal tracts of humans and other mammals. In a study on the enterococcal flora of swine, E. malodoratus was found in the intestines and feces. It was not identified within the tonsils of swine, nor within cats, calves, dogs, horse, or poultry. The name "malodoratus" translates to "ill smelling".
Fannyhessea vaginae is a species of bacteria in the family Atopobiaceae. It is a facultative anaerobic, Gram-positive rod-shaped or elliptical coccobacillus found as single elements or in pairs or short chains. It is typically isolated from 80% of women with bacterial vaginosis and it is implicated in treatment failures. Invasive infections such as bacteremia have been reported.
Enterococcus mundtii is a species of Enterococcus. Its genome has been sequenced. The type strain is NCDO 2375.
Christensenella hongkongensis is a species of clinically relevant gram-positive coccobacilli, first isolated from patients in Hong Kong and Canada in 2006. Although the species remains relatively rare, it has a high mortality rate of up to 50%. Christensenella is thought to be broadly distributed globally, as it has been isolated from patient blood cultures around the world including Hong Kong, South Korea, New Zealand, Canada, Sweden, France and Italy. Fewer than 15 cases of C. hongkongensis have been observed worldwide.
