Vancomycin-resistant enterococci (VRE)

Enterococci are gram-negative, rod-shaped bacteria that commonly live in the gasrointestinal tract, and can cause infection anywhere in the body.

They are resistant to several antibiotics,Including ampicillin, the vancomycin and aminoglycosides.

Previously vancomycin was effective treatment for enterococcal infections, but some enterococci have become resistant.

The two main species that are clinically significant are vancomycin-resistant Enterococcus faecium and vancomycin-resistant Enterococcus faecalis, with E. faecium being the most common.

Vancomycin resistance is acquired when a sensitive Enterococcus acquires a plasmid.

VRE appears able to transfer vancomycin resistance to unrelated bacteria.

VRE organisms are usually resistant to more than one antibiotic.

Linezolid and quinupristin-dalfopristin Approved for the treatment of VRE.

Approximately 30% of all enterococcal infections are now caused by vancomycin-resistant strains.

VRE can exist in a colonized state, usually in the bowel.

If the number of VRE bacteria increases, they can invade the bloodstream and can cause meningitis, pneumonia, endocarditis, wound infection and locally to cause an abdominal infection.

Enterococci produces proteases that help them break down the normal barriers between the gut tissue and the bloodstream.

Risk factors include impaired immunity, the presence of chronic illnesses, diabetes and prior antibiotic exposure.

Prior bowel mucosal injury, gastrointestinal procedures, or surgery, the presence of indwelling urinary catheters, intravenous lines increase the risk of VRE infections.

VRE can be transmitted from person to person.

Transmission of VRE especially common in hospitals or chronic-care facilities, as fecal material from an infected or colonized patient can contaminate the environment and be spread on the hands of health-care personnel.

Patients with VRE may contaminate their beds and bathrooms.

VRE cultured from blood or spinal fluid, it almost invariably indicates infection.

VRE is cultured from sputum, urine, or a wound, it could indicate either colonization or infection.

Treatment of VRE with combinations of teicoplanin (Teichomycin) and amoxicillin or a combination of ampicillin imipenem, and vancomycin.

VRE antibiotic susceptibilities done for each infection helps guide the selection of antibiotic treatment.

Augmenting the antimicrobial treatment of VRE-infected patients, includes draining abscesses, removing an infected intravenous line, and to remove urinary catheters to facilitate treatment.

Colonized, but not infected, patients do not require treatment, and there is no established way to eradicate colonization of the stool once it occurs.

Infections can be endemic in institutions.

Residents in long-term facilities can be a reservoir for infections.

VRE infections can be cured in most patients.

Clinical outcome of VRE infections is often more dependent on the underlying disease than on the infecting organism.

The duration of treatment depends on the site of infection.

The best way to prevent infection is to prevent transmission, so that healthcare facilities must utilize infection-control guidelines to reduce the spread of VRE from patient to patient.

Such patient oriented measures include: patient hand washing after using the bathroom and before and after touching the mouth or nose, minimizing the use of intravenous catheters, and urinary catheters and they should removed as soon as possible when no longer needed, and antibiotics should be used only for appropriate indications.

Healthcare workers should follow good hand hygiene principles. washing hands or using alcohol disinfectants on hands before and after touching the patient or objects in the patient’s environment.

Gloves may be used to help clean the bed or the patient.

In a hospital setting VRE infected patients should be in a private room and placed on contact precautions, with gowned and gloved visitors and staff.

VRE can cause sepsis, urinary infection, abscesses, wound infections, pneumonia, endocarditis or meningitis.

More than 90% of hospital isolates are Enterococcus faecium.

The two main species that cause problems are vancomycin-resistant Enterococcus faecium and vancomycin-resistant Enterococcus faecalis

Routine use of gowns with gloves can reduce VRE transmission by half in an ICU setting.

Enterococcus gallinarum and Enterococcus casseliflavus express low-level resistance to vancomycin and should be treated with penicillin.

E. faecalis and E. faecium demonstrate acquired resistance to vancomycin.

Resistant enterococci (VRE)-resistance to vancomycin outside the hospital setting is rare in the U.S.

Primarily a nosocomial disease with approximately 12% of enterococci infections from ICU’s and 11.5% of non-ICU patient enterococci isolates are VRE.

Combination therapy with a cell wall–active agents such as ampicillin, and vancomycin and an aminoglycoside is necessary to adequately treat enterococcal endocarditis.

At least 4 weeks of combination therapy is recommended for the treatment of enterococcal endocarditis, and 6 weeks of such therapy is recommended for patients with symptoms that persisted for more than 3 months prior to starting therapy, in patients who relapsed, and in those with prosthetic valves.

Combination therapy is also recommended to treat enterococcal meningitis, usually for at least 2-3 weeks.

Intravenous linezolid or intravenous plus intraventricular quinupristin-dalfopristin have also been used to successfully treat meningitis.

Vancomycin is used to treat infections with strains that exhibit resistance to ampicillin, gentamicin or streptomycin.

For gentamicin-resistant strains, the only alternative is streptomycin, as tobramycin and amikacin are not active.

For E faecalis infection, prolonged therapy with high doses of ampicillin plus imipenem-cilastatin or ampicillin plus ceftriaxone may be considered.

For E faecium infection, either linezolid or daptomycin may be effective, and quinupristin-dalfopristin or tigecycline could be considered.

For VRE infections, treatment depends on infection severity and in vitro susceptibility of the strain to other antibiotics.

Uncomplicated urinary tract infections with VRE have been treated successfully with nitrofurantoin.

Isolates that remain relatively susceptible to penicillin or ampicillin may be treated with high doses of these agents.

Doxycycline, chloramphenicol, and rifampin in various combinations have been used to treat VRE infections.

Linezolid, an oxazolidinone antibiotic, is available orally and intravenously and is used to treat infections caused by E faecium and E faecalis strains, including VRE.

Linezolid is useful in patients who require oral or outpatient therapy and who are intolerant to glycopeptides, or who have impaired renal function.

Linezolid-resistant VRE isolates have already been reported.

Daptomycin, a lipopeptide antibiotic that works by altering the bacterial membrane function, is indicated for the treatment of vancomycin-susceptible E faecalis– complicated skin infections.

Daptomycin has bactericidal activity against enterococci even when used as sole antibiotic therapy.

Daptomycin resistance in VRE isolates has been reported.

Tigecycline, a glycylcycline antibiotic used to treat gram-positive, gram-negative, and anaerobic bacterial infections, can also be used to treat VRE, with limited data.

Telavancin is a lipoglycopeptide that is rapidly bactericidal against a broad spectrum of aerobic and anaerobic gram-positive pathogens.

Telavancin is approved for the treatment of adult patients with complicated skin and skin structure infection due to numerous aerobic gram-positive organisms, including vancomycin-susceptible isolates of E faecalis, and many vancomycin-resistant isolates of Enterococcus.

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