ShareCompartir Vancomycin-resistant Enterococci are specific types of antimicrobial-resistant bacteria that are resistant to vancomycin, the drug often used to treat infections caused by enterococci. Enteroccocci are bacteria that are normally present in the human intestines and in the female genital tract and are often found in the environment. These bacteria can sometimes cause infections.
Advanced Search Abstract Enterococci are not generally regarded as highly virulent bacterial pathogens. However, resistance to many antimicrobial drugs complicates treatment of enterococcal infections. Acquired resistance to high concentrations of glycopeptide antibiotics, specifically vancomycin, has exacerbated this problem.
This article seeks to concisely review the mechanisms of that resistance and its effects on clinical management of enterococcal infections, as well as clinical microbiology and infection control. Enterococcus gallinarum and Enterococcus casseliflavus are relatively infrequent causes of human infection.
In contrast, Enterococcus faecalis and Enterococcus faecium cause the great majority of enterococcal infections. When clinical isolates of Vancomycin resistance entercocci enterococcal species with acquired vancomycin resistance began to appear in the late s, it prompted significant changes in testing of enterococci in the clinical microbiology laboratory, infection control of enterococci, and treatment of enterococcal infections [ 1 ].
Enterococci are normal inhabitants of the alimentary canal and cause urinary tract infections, bacteremia, and endocarditis. They are also commonly recovered from infections of the abdomen, the pelvis, the biliary tract, and wounds, settings in which polymicrobial flora are common.
Enterococci less frequently cause infections of other sites, for example, bone, joints, and the meninges. Data collected by the National Nosocomial Infections Surveillance System on infections in patients in intensive care units from through showed that enterococci were the third most common bloodstream isolate, the third most common urinary isolate, the most common isolate from surgical site infections, and the fourth most common isolate from all sites [ 2 ].
Enterococci are primarily opportunistic pathogens. The increasing severity of illness in hospitalized patients has contributed to the ascendance of enterococci as nosocomial pathogens.
Progress in medical technology and treatment, such as the use of various intravascular access devices, implanted prosthetic devices, cytotoxic chemotherapy, and immunosuppression, has magnified the impact of organisms of relatively low virulence, such as enterococci.
Of critical import is the intensive use of relatively broad-spectrum antibiotics in the hospital, which provides selective pressure favoring the growth of intrinsically drug-resistant commensal organisms such as enterococci.
Resistance to a number of antimicrobial drugs is a characteristic of the genus Enterococcus table 1 [ 3 ], although some species e.
Enterococci obtained from antibiotic-naive populations in the Solomon Islands demonstrated resistance to penicillinase-resistant penicillins, cephalosporins, clindamycin, and low levels of both penicillins and aminoglycosides [ 4 ].
Although the combination of trimethoprim and sulfamethoxazole may appear to be active against enterococci in vitro, the microorganisms are presumed to be clinically resistant by virtue of their ability to use exogenous folate, thus circumventing the mechanism of action of those drugs [ 6 ].
Tolerance is the ability of the organism to survive levels of drugs well in excess of the MIC. Tolerance to cell wall-active drugs e. It was subsequently demonstrated that these strains could be made tolerant by exposure to pulsed doses of penicillin [ 7 ].
Table 1 Intrinsic and acquired antimicrobial drug resistance in enterococci. Table 1 View large Download slide Intrinsic and acquired antimicrobial drug resistance in enterococci.
Through mutation and transfer of resistance genes from other species and in some cases between enterococcal speciesenterococci have acquired additional resistance determinants table 1. Resistance to fluoroquinolones, in excess of the modest intrinsic resistance found in many enterococci, is mediated by alterations in enzymes involved in DNA replication [ 11 ].
Other common acquired genetic determinants confer resistance to macrolides, tetracycline, and chloramphenicol. Chromosomal mutations may occur that produce resistance to rifampin and fusidic acid, among others.
Because of all of the problems with drug resistance outlined above, vancomycin was a reliable and critically important antimicrobial for the treatment of enterococcal infections. Phenotypes, Genotypes, and Mechanisms if Glycopeptide Resistance in Enterococci The first report of enterococci resistant to high concentrations of glycopeptide antibiotics vancomycin and teicoplanin was published inwhen Uttley et al.
At that time, use of vancomycin and teicoplanin the latter has not been approved for use in the United States had been growing rapidly, in part because of the increasing use of intravascular devices combined with the high prevalence of methicillin resistance among staphylococci.
Also, orally administered vancomycin was a widely used treatment for Clostridium difficile colitis. Consumption of huge quantities of glycopeptides was also occurring in an entirely different population; specifically, avoparcin another glycopeptide drug was being used as a growth promoter in food animals.
This use of a glycopeptide at subtherapeutic concentrations in animals may have played a role in the development of acquired vancomycin resistance in enterococci [ 12 ].
Various types of vancomycin-resistant enterococci VRE have been characterized on phenotypic and genotypic bases, as summarized in table 2 [ 13 ]. Resistance is induced by the presence of either drug [ 14 ]. They typically retain susceptibility to teicoplanin, which has not been seen to induce resistance [ 15 ].
Evidence of transfer of these resistance genes beyond the genus Enterococcus includes the finding of several gram-positive species carrying vanA and a stool isolate of Streptococcus bovis carrying vanB [ 16 ]. The ability of these genes to be expressed in diverse hosts was demonstrated by the experimental laboratory transfer of vanA to S.
Fortunately, we are as yet unaware of any transfer of these genes to S. Less common phenotypes of acquired glycopeptide resistance include VanD, which has been described in several isolates of E.Vancomycin Resistance Entercocci.
Topics: Antibiotic resistance, Bacteria, Health care Pages: 3 ( words) Published: November 28, Every year lives are lost because of the spread of infections in hospitals. Infection control is an important part of the health care system; it refers to the policies used to decrease the risk of.
Vancomycin is an antibiotic that is often used to treat these infections. Antibiotics are medicines that are used to kill bacteria. Enterococcus germs can become resistant to vancomycin and therefore are not killed.
These resistant bacteria are called vancomycin-resistant enterococci (VRE). Nearly all strains of Enterococcus gallinarum are resistant to low levels of vancomycin. The glycopeptide resistance gene vanC from E. gallinarum BM has recently been cloned and sequenced. A probe specific for vanC hybridized with a kb EcoRI and a kb HindIII fragment of total DNA from the 42 strains of E.
gallinarum studied. What is a vancomycin resistant enterococcus (VRE)? VRE is a strain of bacteria that can cause infection. Usually the antibiotic vancomycin is used to kill the bacteria. However, VRE is resistant to vancomycin and makes it difficult to treat.
VRE most commonly causes an . Vancomycin is an antibiotic that is used to treat some drug-resistant infections caused by enterococci. In some instances, enterococci have become resistant to this drug and thus are called vancomycin-resistant enterococci (VRE).
Vancomycin-resistant Enterococci (VRE) and the Clinical Laboratory. Recommend on Facebook Tweet Share Compartir. What are the types of vancomycin resistance in enterococci? There are the two types of vancomycin resistance in enterococci. The first type is intrinsic resistance.