raffinosus have been isolated from patients diagnosed with enterococcal infections (241). Because of their near-ubiquitous distribution in the feces of animals, including humans, they are commonly used as FIB, or surrogates for pathogens, in water quality analyses (see Use of Enterococci as Fecal Indicator Bacteria).
raffinosus, E. avium, E. durans, and several other enterococcal species. Several genes, including vanA, vanB, vanC, vanD, and vanE, contribute to resistance to vancomycin in enterococci.
Enterococcus species are gram-positive, facultative anaerobic cocci that are morphologically similar to streptococci on Gram stain (181).
E. faecalis infections spread from person to person through poor hygiene. Because these bacteria are found in feces, people can transmit the infection if they don’t wash their hands after using the bathroom. The bacteria can get into food or onto surfaces such as doorknobs, telephones, and computer keyboards.
Ampicillin is the drug of choice for monotherapy of susceptible E faecalis infection. For most isolates, the MIC of ampicillin is 2- to 4-fold lower than that of penicillin.
There are two different species of Enterococcus known as frequent pathogens in humans: Enterococcus faecium and Enterococcus faecalis. Both species can become MDROs, but E. faecium is more likely to do so; high-level resistant strains of E. faecium are associated with 30% mortality.
Ampicillin plus ceftriaxone is as effective as ampicillin plus gentamicin for treating enterococcus faecalis infective endocarditis.
Enterococcus faecalis and E. faecium cause a variety of infections, including endocarditis, urinary tract infections, prostatitis, intra-abdominal infection, cellulitis, and wound infection as well as concurrent bacteremia. Enterococci are part of the normal intestinal flora.
E. gallinarum and E. casseliflavus, the VanC enterococci, are intrinsically resistant to vancomycin at concentrations typ- ically lower than or equal to 32 mg/mL, although these species may acquire additional Van determinants, resulting in higher MICs.
VRE infections can be cured in most patients, and the outcome is often more dependent on the underlying disease than on the infecting organism. The duration of treatment depends on the site of infection. For example, heart-valve infections may require six weeks of antibiotic therapy.
Antibiotic resistance occurs when the germs no longer respond to the antibiotics designed to kill them. If these germs develop resistance to vancomycin, an antibiotic that is used to treat some drug-resistant infections, they become vancomycin-resistant enterococci (VRE).
Enterococcus faecalis is a gram-positive bacterium that can cause a variety of nosocomial infections of which urinary tract infections are the most common. These infections can be exceptionally difficult to treat because of drug resistance of many E. faecalis isolates.
How to Treat Enterococcal Infections. One course of treatment involves combining a wall-active drug — such as penicillin, ampicillin, amoxicillin, piperacillin, or vancomycin — with what’s called an aminoglycoside — such as gentamicin or streptomycin.
Unlike streptococcal species, enterococci are relatively resistant to penicillin, with minimum inhibitory concentrations (MICs) that generally range from 1-8 mcg/mL for E faecalis and 16-64 mcg/mL for E faecium.
faecium and E. faecalis strains are used as probiotics and are ingested in high numbers, generally in the form of pharmaceutical preparations. Such probiotics are administered to treat diarrhoea, antibiotic-associated diarrhoea or irritable bowel syndrome, to lower cholesterol levels or to improve host immunity.
faecium may be pathogenic and harmful to humans, and can cause bacteraemia, endocarditis, urinary tract and other infections. Moreover, anti-microbial resistance (AMR) to many commonly used antibiotics has been reported, and E. faecium is the leading cause of multi-drug resistant enterococcal infections in humans.
Symptoms usually appear between 6 hours and 6 days after the initial infection and last 4–7 days, according to the CDC.
Enterococci have become an increasingly common cause of UTI, accounting for greater than 30% of all bacterial isolates causing UTI among hospitalized patients.
Results indicated that enterococci might be a more stable indicator than E. coli and fecal coliform and, consequently, a more conservative indicator under brackish water conditions.
The increased prevalence of enterococcal urinary tract infection is probably the result of increasing use of catheterization and broad-spectrum antibiotics. Glycopeptides reach high levels in the urine, and teicoplanin might be an alternative for the treatment of urinary tract infections due to enterococci.
All enterococci exhibit decreased susceptibility to penicillin and ampicillin, as well as high-level resistance to most cephalosporins and all semi-synthetic penicillins, as the result of expression of low-affinity penicillin-binding proteins.
MDRO Definition. For epidemiologic purposes, MDROs are defined as microorganisms, predominantly bacteria, that are resistant to one or more classes of antimicrobial agents (1).
- Urinary tract infections (UTIs)
- Blood infections.
- Wound infections.
Ciprofloxacin, considered to have only modest activity against enterococci,2 is not used as a drug of first choice but has been successfully employed in the treatment of enterococcal UTIs.
Amoxicillin is the drug of choice for the treatment of enterococcal UTIs. Second-line therapies include vanco- mycin and nitrofurantoin.
Piperacillin in combination with tazobactam is active against enterococci that produce beta-lactamase and, in combination with an appropriate aminoglycoside, could be a viable choice for therapy of enterococci that do not have high-level resistance to all aminoglycosides.
In some studies, E. faecium bacteremia is associated with a higher mortality rate than E. faecalis (Noskin, Peterson, & Warren, 1995), and patients with rapidly fatal underlying diseases can have mortality rates as high as 75%.
Enterococcus faecalis is a commensal organism of the intestinal tract. However, it may be a causative agent of diarrhea in elderly and immunocompromised patients.
Enterococcus faecium is a Gram-positive, coccal shaped, facultative anaerobic bacterium that can occur in pairs or chains. Its natural habitat includes the gastrointestinal tract, oral cavity, and vaginal tract of a wide variety of animals. The colonies that are produced appear wet and have an average size of 1-2 mm.
On the other hand, vancomycin induces the synthesis of the resistance proteins of both systems, and in fact, if a teicoplanin-susceptible enterococcus with the vanB gene cluster is preexposed to vancomycin, the strain then tests teicoplanin resistant as well.
The main mechanism of glycopeptide resistance (e.g., vancomycin) in enterococci involves the alteration of the peptidoglycan synthesis pathway, specifically the substitution of D-Alanine-D-Alanine (D-Ala-D-Ala), to either D-Alanine-D-Lactate (D-Ala-D-Lac) or D- Alanine-D-Serine (D-Ala-D-Ser).
Vancomycin-resistant enterococci infections are treated with antibiotics, which are the types of medicines normally used to kill bacteria. VRE infections are more difficult to treat than other infections with enterococci, because fewer antibiotics can kill the bacteria.
Because patients with VRE can remain colonized for long periods after discharge from the hospital, establish a system for highlighting the records of infected or colonized patients so they can be promptly identified and placed on isolation precautions upon readmission to the hospital.
Enterococcal infections that result in human disease can be fatal, particularly those caused by strains of vancomycin-resistant enterococci (VRE).
VRE, which was estimated to have caused 54,500 infections among hospitalized patients and led to the deaths of 5,400 people, is listed in the “serious” category.
Enterococcus faecalis is a Gram-positive, nonmotile, facultative anaerobic microbe. Vancomycin Resistant Enterococcus (VRE) are strains that are resistant to the antibiotic vancomycin.
Interestingly, remarkably high proportions of VREF were observed in isolates from patients treated in prevention and rehabilitation care centres, where more than one third of all E. faecium isolates are found to be resistant to vancomycin (36.7% [CI 95% 26.8–47.9%].
Enterococci are Gram-positive facultative anaerobic cocci in short and medium chains, which cause difficult to treat infections in the nosocomial setting. They are a common cause of UTI, bacteremia, and infective endocarditis and rarely cause intra-abdominal infections and meningitis.
Routine therapy for asymptomatic bacteriuria with MDR-Enterococcus is not recommended. Removal of indwelling urinary catheters should be considered. Appropriate antibiotic therapy selection should be guided by urine culture and susceptibility results.
Treat VRE cystitis with at least seven days of antimicrobial therapy. Treat bacteremic VRE UTIs and pyelonephritis with 10 – 14 days of antimicrobial therapy for most cases. CA-UTI due to VRE may be treated with 3 days of therapy in women <65 years old without upper tract symptoms after urinary catheter removal.