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1 Şubat 2017 Çarşamba

Vancomycin Resistant Enterococcus: a current overview of diagnosis, prevention and treatment

Although many enterococcus species can be held responsible for VRE, Enterococcus faecum and Enterococcus faecalis constitute 95% of VRE infections.
We can add vancomycin resistant strains such as E. gallinarus and E.casselflavius ​​to these, but these two organisms are more or less related to colonization. Their pathogens are low and they can live in nature for years.
Vancomycin inhibits enterococci by binding to the D-alanyl-D-alanine (D-Ala-D-Ala) terminal of cell wall precursors.
In the case of residence, the D-Ala-D-Ala terminus is replaced by the D-Ala-D-lactate termination. Vancomycin binds to this end with low affinity. As a result, the MIC value for vancomycin is almost 1000 fold.
The accepted MIC value for vancomycin susceptibility is ≤4 mcg / mL, while the value that is resistant is considered to be ≥32 mcg / mL. Values ​​between 8-16 mcg / mL Vancomycin is considered to be intermediate, at which Vancomycin is not preferred.
Pulse-field gel electrophoresis (PFGE) is used in the analysis of both endemic and epidemic clusters of VRE infection and colonization.
The vast majority of VREs are Enterococcus faecum.

Risk factors
  • Previous antibiotic therapy history is the most common risk factor for VRE. Vancomycin and cephaloporins are prominent antibiotics. Ceftazidime has been found one of the most prominent in a study.
  • Administration of antibiotics for anaerobic treatment is known to increase the intensity of the fecal colonization of VRE, which decreases after the antibiotic is discontinued.

Patient characteristics
  • More than 72 hours of hospital stay, important underlying medical conditions, need for ICU and invasive devices.
  • Colonization pressure
  • Exposure to contaminating surfaces
  • Patient from care centers

The patient known to be colonized with VRE is estimated to have been colonized for at least 1 year.
The percentage of VRE infection development in patients who are contaminating with VRE is about 8%. This rate is higher in severely ill patients and those with immunodeficiencies.
Routine surveillance cultures are not recommended to detect colonized patients with VRE in non-epidemic centers. Active surveillance cultures are recommended for high-risk patients and are recommended for centers with increased frequency of VRE.
The most important method of protection is hand washing. In particular, it should be ensured that health personnel take into account contact measures.
VRE hasta odasındaki yüzeylerde saatlerce-günlerce kalabilmektedir.
VRE description: Vancomycin resistance is defined as ≤ 16 mm by disc diffusion method or 8 μg / ml by agar dilution method (MIC) or automated methods.
To say that there is an epidemic; We need to show that in the healthcare facility, 3 or more infections with clinical significance have been acquired within 7 days.
Optimal antibiotic treatment in infected patients with VRE has not been definitively identified. Linezolid is FDA approved. While quinopristin-dalfopristin has been FDA approved in the past, this approval has been lifted due to ineffectiveness.
E.faecalis, like E. gallinarus and E.casselflavius, are generally susceptible to beta-lactams.
Linezolid, daptomycin and tigecycline have activity against both E. faecium and E. faecalis.
The effect of quinopristin-dalfopristin is only against E. faecum, not against E. faecalis.

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