Treatment Of Vancomycin-resistant Enterococci Research Articles

New Mutations in cls Lead to Daptomycin Resistance in a Clinical Vancomycin- and Daptomycin-Resistant Enterococcus faecium Strain

Daptomycin (DAP), a last-resort antibiotic for treating Gram-positive bacterial infection, has been widely used in the treatment of vancomycin-resistant enterococci (VRE). Resistance to both daptomycin and vancomycin leads to difficulties in controlling infections of enterococci. A clinical multidrug-resistant Enterococcus faecium EF332 strain that shows resistance to both daptomycin and vancomycin was identified, for which resistance mechanisms were investigated in this work. Whole-genome sequencing and comparative genomic analysis were performed by third-generation PacBio sequencing, showing that E. faecium EF332 contains four plasmids, including a new multidrug-resistant pEF332-2 plasmid. Two vancomycin resistance-conferring gene clusters vanA and vanM were found on this plasmid, making it the second reported vancomycin-resistant plasmid containing both clusters. New mutations in chromosomal genes cls and gdpD that, respectively, encode cardiolipin synthase and glycerophosphoryl diester phosphodiesterase were identified. Their potential roles in leading to daptomycin resistance were further investigated. Through molecular cloning and phenotypic screening, two-dimensional thin-layer chromatography, fluorescence surface charge test, and analysis of cardiolipin distribution patterns, we found that mutations in cls decrease surface negative charges of the cell membrane (CM) and led to redistribution of lipids of CM. Both events contribute to the DAP resistance of E. faecium EF332. Mutation in gdpD leads to changes in CM phospholipid compositions, but cannot confer DAP resistance. Neither mutation could result in changes in cellular septa. Therefore, we conclude that the daptomycin resistance of E. faecium EF332 is conferred by new cls mutations. This work reports the genetic basis for vancomycin and daptomycin resistance of a multidrug-resistant E. faecium strain, with the finding of new mutations of cls that leads to daptomycin resistance.

Infecciones por enterococos

Enterococci are facultative anaerobic gram-positive bacteria that are arranged in chains or pairs. The most relevant species are Enterococcus faecalis and Enterococcus faecium. They are normal colonizers of the digestive system. They can survive on surfaces and in hospital settings for an extended period of time. Frequent contact with hospitals, comorbidities, prior antibiotic use, and presence of medical devices are associated with a greater risk of infection. They can give rise to multiple clinical syndromes and are more common in healthcare-associated infections than community infections. Of note are urinary tract infections, intra-abdominal infections, venous catheter-related bacteremias, endocarditis, meningitis, and surgical wound infections. The presence of endocarditis must be evaluated in all enterococci bacteremias; the NOVA and DENOVA scores are useful for doing so. Enterococcus faecalis tend to be sensitive to ampicillin, which is the treatment of choice. In cases of endocarditis or complicated bacteremia, it is recommended to combine them with ceftriaxone or gentamicin. Enterococcus faecium tend to be resistant to ampicillin and the treatment of choice is vancomycin. Treatment of vancomycin-resistant enterococci is not well-defined and represents a challenge; the main options are daptomycin at high doses or linezolid. Adequate control of the source of the infection is fundamental in the management of enterococcal infections.

Determination of Antimicrobial Activity of Various Plant Essential Oils on Vancomycin Resistant Enterococci (VRE) and Some Pathogenic Microorganisms

In this study, it was aimed to determine the anti-bacterial activities of plant essential oils such as thyme, rosemary, sage, linden, black seed, bay leaf, peppermint, parsley, cinnamon and oleagen on vancomycin resistant enterococci (VRE) and pathogenic microorganisms of clinical importance. In the study, the inhibition zones of the plant extract of 10 plants prepared at 2.5 and 5 mg / mlconcentrations of VRE and various pathogenic microorganisms were detected by Disk Diffusion and Agar Well Diffusion Method. Following this, Minimal Inhibition Concentration (MIC) values of these extracts were determined. The activities of plant extracts on DNA and Gas Chromatography-Mass Spectrometry (GC-MS) analyzes were also performed. According to the data obtained, it was determined that the extracts of rosemary and sage plants showed high antibacterial effect against pathogenic bacteria. The rosemary extract was found to be the most effective extract on VRE strains, as well as medium-grade antibacterial effects on the VRE strains in oleaster, linden, thyme and mint extracts. It was also determined that extracts from different plants did not cause any change in the structure of DNA. In our study, it was determined that plant extracts that are especially effective on VRE strains have the potential to be used in the treatment of VRE. The results of this study should be taken into account in the research of drugs that can be used in the treatment of VRE and more in vitro and in vivo research should be carried out in this field.

Optimization of Linezolid Dosing Regimens for Treatment of Vancomycin-Resistant Enterococci Infection.

BackgroundLinezolid, an oxazolidinone antibiotic, is recommended for vancomycin-resistant enterococci (VRE). However, 100% free-drug concentration above the minimum inhibitory concentration (fT>MIC) and an area under the curve of free drug to MIC ratio (fAUC24/MIC) >100 were associated with favorable clinical outcome with less emerging resistance. A plasma trough concentration (Ctrough) of linezolid ≥9 µg/mL was also related to hematologic toxicity. Thus, linezolid dose optimization is needed for VRE treatment. The study aimed to determine the in vitro linezolid activity against clinical VRE isolates and linezolid dosing regimens in critically ill patients who met the target pharmacokinetics/pharmacodynamics (PK/PD) for VRE treatment.Materials and MethodsEnterococcal isolates from enterococcal-infected patients were obtained between 2014 and 2018 at Phramongkutklao Hospital. We used Monte Carlo simulation to calculate the probability of target attainment, and the cumulative fraction of response (CFR) of the free area under the curve to MIC ratio (fAUIC24) was used to calculate the fAUC24/MIC 80 - 100 and fT/MIC >85 - 100% of the interval time of administration for clinical response and microbiological eradication as well as the Ctrough ≥9 µg/mL for the probability of hematologic toxicity.ResultsFor linezolid MIC determination, the MIC median (MIC50), MIC for 90% growth (MIC90), and range for linezolid were 1.5 µg/mL, 2 µg/mL, and 0.72 - 2 µg/mL, respectively. A dosing regimen of 1,200 mg either once daily or as a divided dose every 12 h gave target attainments of fAUC24/MICs >80 and >100, which exceeded 90% for MICs ≤1 and ≤1 µg/mL, respectively, with a rate of hematologic toxicity <15%. If the expected fT>MICs were >85% and 100%, a 1,200-mg divided dose every 12 h could cover VRE isolates having linezolid MICs ≤1 µg/mL and ≤0.75 µg/mL. Even 600 mg every 8 h and 1,200 mg as a continuous infusion gave a higher target attainment of fAUC24/MIC and a fT>MIC and the target CFR, but those regimens gave Ctrough ≥9 µg/mL rates of 40.7% and 99.6%.ConclusionThe current dosing of 1,200 mg/day might be optimal treatment for infection by VRE isolates with documented MICs ≤1 µg/mL. For treatment of VRE with a MIC of 2 µg/mL or to achieve the target CFR, the use of linezolid with other antibiotic combinations might help achieve the PK/PD target, provide better clinical outcome, and prevent resistance.

Impact of Positive Vancomycin-Resistant Enterococcus (VRE) Screen Result on Appropriateness of Definitive Antibiotic Therapy

Background: Vancomycin-resistant Enterococcus (VRE) screening has been utilized to identify colonized patients to prevent transmission. However, little is known about the utility of screening to guide antibiotic therapy. We assessed the appropriateness of definitive therapy in patients with a VRE screen and evaluate the predictive value of screening for the development of a VRE infection. Methods: In this retrospective study, we evaluated VRE screening of patients aged 18 years admitted between June 1, 2015, and May 31, 2018, to a 280-bed, academic, tertiary-care hospital. Rectal swabs were tested using Cepheid Xpert. Screening was performed routinely on admission for hematologic malignancy and liver transplantation patients. Only the first screen result was included for patients who had multiple VRE screens. The patient was classified as having a VRE infection if any Enterococcus isolates were vancomycin resistant. The primary outcome was appropriateness of antibiotic therapy in patients who had a VRE screen. Appropriateness of VRE-directed therapy was defined as therapy with linezolid or daptomycin for patients who had a positive VRE culture and an identifiable source of infection, or who had no clinical improvement on alternative therapy, or who had a documented β-lactam allergy. If appropriateness was unclear, 2 infectious diseases specialists determined appropriateness. Results: In total, 1,374 patients who had a rectal VRE screen met inclusion criteria. Of these, 1,053 (88%) had a negative screen. We detected no difference in the appropriateness of VRE-directed therapy between patients with a positive screen and those with a negative screen (59.3% vs 61.0%; P = .8657). The VRE screen had a sensitivity of 60% (95% CI, 43%–74%), specificity of 90% (95% CI, 88%–92%), positive predictive value of 18% (95% CI, 12%–25%), and negative predictive value of 98% (95% CI, 97%–99%) for VRE infection. Conclusions: Although VRE screening may have utility to detect colonization in high-risk patients, a positive VRE screen is of limited value in determining the need for VRE-directed therapy. Patients with a negative VRE screen have a low likelihood of developing a VRE infection, and a negative screen could be used to identify patients who may not require empiric coverage for VRE. Further research is needed to determine optimal utilization of VRE screening for prediction and treatment of VRE infections.Funding: NoneDisclosures: None

Linezolid induced thrombocytopenia

Linezolid, an oxazolidinone antibiotic active against gram-positive bacteria is used in the treatment of vancomycin resistant Enterococci and MRSA. It is generally tolerated except for the 32% chance of thrombocytopenia on long term usage of linezolid. A 25-year-old male after renal transplantation was administered linezolid for antibiotic prophylaxis. His platelet count dropped from 1,68,000 cells to 74,000 on day 2. The platelet counts further dropped to 58,000 on day 3, followed which linezolid was withdrawn. His platelet improved to 88,000 on day 5 following withdrawal of linezolid. Though we are vigilant about thrombocytopenia on long term usage of linezolid, here we report a rare case of linezolid induced thrombocytopenia within 2 days of starting the antibiotic. This necessitates the increased vigilance on linezolid usage. Platelet count needs to be monitored as early as the start of treatment with linezolid.

Optimizing the Dosing Regimens of Daptomycin Based on the Susceptible Dose-Dependent Breakpoint against Vancomycin-Resistant Enterococci Infection.

Daptomycin, a lipopeptide antibiotic, is one of the therapeutic options used for the treatment of vancomycin-resistant enterococci (VRE). Recently, the Clinical and Laboratory Standards Institute (CLSI) M100 30th edition has removed the susceptibility (S) breakpoint for Enterococcus faecium and replaced it with a susceptible dose-dependent (SDD) breakpoint of ≤4 μg/mL, with a suggested dosage of 8–12 mg/kg/day. Herein, we aimed to determine the minimum inhibitory concentration (MIC) values of daptomycin against clinical VRE isolates and to study the appropriate daptomycin dosing regimens among critically ill patients based on the new susceptibility CLSI breakpoint. The MIC determination of daptomycin was performed using E-test strips among clinical VRE strains isolated from patients at the Phramongkutklao Hospital. We used Monte Carlo simulation to calculate the probability of target attainment (PTA) and the cumulative fraction of response (CFR) of the ratio of the free area under the curve to MIC (fAUC0–24/MIC) > 27.4 and fAUC0–24/MIC > 20 for survival and microbiological response, respectively, at the first day and steady state. Further, we determined that the simulated daptomycin dosing regimen met the minimum concentration (Cmin) requirements for safety of being below 24.3 mg/L. All of the 48 VRE isolates were E. faecium strains, and the percentiles at the 50th and 90th MIC of daptomycin were 1 and 1.5 μg/mL, respectively. At MIC ≤ 2 μg/mL, a daptomycin dosage of 12 mg/kg/day achieved the PTA target of survival and microbiological response at the first 24 h time point and steady state. For a MIC of 4 μg/mL, none of the dosage regimens achieved the PTA target. For CFR, a dosage of 8–12 mg/kg/day could achieve the 90% CFR target at the first day and steady state. All dosing regimens had a low probability of Cmin being greater than 24.3 mg/L. In conclusion, the MIC of VRE against daptomycin is quite low, and loading and maintenance doses with 8 mg/kg/day were determined to be optimal and safe.

In vitro activity of linezolid alone and combined with other antibiotics against clinical enterococcal isolates.

The increasing incidence of antimicrobial resistance has led to research on finding new antimicrobial agents or identifying drug combinations with synergistic effects. Enterococcal infections, particularly those associated with vancomycin-resistant enterococci (VREs), are therapeutic problems. Linezolid (LZD), an oxazolidinone antibiotic, shows good activity against Gram-positive bacteria including enterococci. To avoid the emergence of linezolid-resistant subpopulations and achieve enhanced activity or bactericidal effect, the use of combined therapy has been considered. The in vitro activity of LZD in combination with five different antibiotics was evaluated using amicrodilution checkerboard method and time-kill study against 12clinical enterococcus isolates. With the checkerboard method, LZD plus doxycycline (DX) had the highest frequency among all synergistic combinations. This combination and the one of LZD plus ceftriaxone (CRO) were the most frequent effective combinations against VREs. Time-kill studies using selected synergistic combinations-LZD+ DX and LZD+ CRO-showed anindifferent interaction. One tested combination of LZD+ rifampicin showed antagonism. Antagonistic interactions in combinations containing LZD are rare. LZD+ DX and LZD+ CRO may be beneficial in the treatment of VREs. However, more time-kill studies as well as in vivo experiments are required.

Efficacy and Safety of High-Dose Daptomycin Versus Linezolid for the Treatment of Vancomycin-Resistant Enterococcus (VRE) Bacteremias: A Retrospective Study

Efficacy and Safety of High-Dose Daptomycin Versus Linezolid for the Treatment of Vancomycin-Resistant Enterococcus (VRE) Bacteremias: A Retrospective Study

Clinical Outcomes of Daptomycin for Vancomycin-resistant Enterococcus Bacteremia

PurposeIn light of recent evidence suggesting enhancement of daptomycin activity against vancomycin-resistant Enterococcus (VRE) by ampicillin and other β-lactam antibiotics, we evaluated the safety profile and clinical efficacy of daptomycin with and without concomitant β-lactam antimicrobials in the treatment of VRE (faecium or faecalis) bacteremia from multiple centers across the United States. MethodsData were collected retrospectively as part of a larger multicenter registry (The Cubicin Outcomes Registry and Experience). Efficacy and clinical outcomes in patients with VRE bacteremia who received at least 3 days of daptomycin with or without concomitant β-lactams were analyzed. Although all the cases involved daptomycin-susceptible VRE, additional analysis was performed to examine whether the adjunctive β-lactam would play a more pivotal role in cases where the daptomycin MIC was in the upper limit of the susceptibility range, indicating that daptomycin monotherapy efficacy may be relatively compromised compared with cases with lower daptomycin MICs. FindingsTwo hundred sixty-two patients from 33 hospitals were evaluated. Most patients had at least one significant comorbidity, such as solid-organ or bone marrow transplantation (16%), neutropenia (36%), dialysis dependency (20%), or critical illness (36%) requiring care in an intensive care unit. Overall treatment success was 86% (n = 225/262), and treatment success for patients taking concomitant β-lactams was 86% (n = 105/122). Logistic regression identified treatment failure to be associated with sepsis (odds ratio = 3.42; P = 0.009) and an elevated daptomycin MIC (3–4 µg/mL) (odds ratio = 3.23, P = 0.013). No significant increase in clinical failure was seen among patients with elevated daptomycin MIC who received concomitant β-lactam therapy (clinical success, 88% vs 79% for MIC ≤2 vs 3–4 µg/mL, respectively; P = 0.417). Of 262 patients, 33 (13%) experienced ≥1 adverse event possibly related to daptomycin (increased creatine kinase in 8 patients). ImplicationsOverall, daptomycin was effective and well tolerated for VRE bacteremia, with lower effectiveness noted with daptomycin MIC of 3 to 4 µg/mL. Concomitant β-lactam therapy with daptomycin may improve clinical outcomes in this setting. Further studies are needed to characterize the potential benefit of concomitant β-lactams with daptomycin.

Clinical Efficacy of Fosfomycin for the Treatment of Complicated Lower Tract and Uncomplicated Urinary Tract Infections

Fosfomycin is an oral antibiotic with activity against multidrug resistant organisms, including vancomycin-resistant enterococcus (VRE) and extended-spectrum β-lactamase (ESBL) producing Enterobacteriaceae. However, there is currently no information describing effiacy of fosfomycin compared to other agents for healthcare associated UTIs. Additionally, there is minimal information characterizing the potential cost savings with utilization of fosfomcyin versus traditional therapies. This retrospective study evaluated clinical and economic outcomes of fosfomycin compared to matched controls. The controls were before the addition of fosfomycin to hospital formulary with recommended prescribing criteria. The fosfomycin group consisted of patients who were admitted to the hospital after the addition of fosfomycin to the hospital formulary with recommended prescribing criteria. Patients receiving fosfomycin for the treatment of UTI were matched to control patients based on pathogen, renal function, and presence of a lower UTI. A total of 86 patients were evaluated. The majority of patients received fosfomycin for the treatment of VRE (45.6%) and ESBL producing Enterbacteriaceae (16.3%) UTIs. Patients with a combination of allergies or documented resistance to fist line agents also received fosfomycin to treat Enterococcus (25.6%), Enterobacteriaceae (7.8%), or polymicrobial UTIs (4.7%). Doxycycline, nitrofurantoin, sulfamethoxazole/trimethoprim, meropenem, and linezolid were the most common antibiotics prescribed in the control group. The average days of treatment were lower in the fosfomycin group (2.93 vs. 7.19 days, p 0.99) and recurrence rates (4.7 vs. 4.7%, p>0.99). Additionally , the mean antibiotic cost per patient was lower in the fosfomycin group ($106.74 vs. $269.55). Adding fosfomycin to formulary resulted in similar clinical success rates and lower cost for the treatment of complicated lower and uncomplicated UTIs.

Therapeutic Options for Resistant Gram Positives

Vancomycin remains the current gold standard for treatment of serious MRSA (methicillin resistant Staphylococcus aureus) infections despite uncertainties about rates of toxicity and the optimal dosing strategy. The only alternative for bloodstream infections (BSI) based on prospective randomised controlled trial data is daptomycin. However, higher doses should be implemented to prevent resistance emerging. Although linezolid and ceftaroline have been shown to be effective BSI treatment in retrospective cohort studies, there is no prospective randomised comparative data with vancomycin. These agents should thus be considered as salvage therapy options. In the treatment of MRSA cSSSIs (complicated skin and skin structure infections), daptomycin, linezolid, ceftaroline and telavancin have all been shown to be equally effective to vancomycin and thus the choice of agent is dependent on the side effect profile and patient setting. In the treatment of nosocomial MRSA pneumonia, both linezolid and telavancin have been shown to be non-inferior to vancomycin. Linezolid was shown to have improved microbiological and clinical cure rates compared with vancomycin, but with no mortality benefit in a randomised controlled trial by Wunderink et al., [1, 2]. Debate still exists, however, as to whether these studies, in the absence of a mortality benefit, provide sufficient evidence to recommend linezolid or telavancin above vancomycin in the treatment of MRSA pneumonia. For the treatment of VRE (Vancomycin Resistant Enterococci) BSI, prospective data is lacking and recommendations are based upon in vitro activity and cohort studies. Quinupristin-dalfopristin is limited by its side effect profile and the need for a central line. As such the first line agents include daptomycin and linezolid. Although two recent meta-analyses suggest improved outcomes with linezolid over daptomycin, this may reflect suboptimal daptomycin dosing rather than linezolid superiority. Tigecycline, although active against VRE, has been shown to be inferior in eradication rates compared with linezolid [3]. Combination therapy for MRSA or VRE infections cannot currently be endorsed and thus should be limited to settings where no other alternative is available.

Optimal control of vancomycin-resistant enterococci using preventive care and treatment of infections

The rising prevalence of vancomycin-resistant enterococci (VRE) is a major health problem in intensive care units (ICU) because of its association with increased mortality and high health care costs. We present a mathematical framework for determining cost-effective strategies for prevention and treatment of VRE in the ICU. A system of five ordinary differential equations describes the movement of ICU patients in and out of five VRE-related states. Two control variables representing the prevention and treatment of VRE are incorporated into the system. The basic reproductive number is derived and calculated for different levels of the two controls. An optimal control problem is formulated to minimize VRE-related deaths and costs associated with prevention and treatment controls over a finite time period. Numerical solutions illustrate optimal single and dual allocations of the controls for various cost values. Results show that preventive care has the greatest impact in reducing the basic reproductive number, while treatment of VRE infections has the most impact on reducing VRE-related deaths.

A Retrospective Comparison of Daptomycin Thrice-Weekly versus Q48H Dosing in Hemodialysis Patients with Vancomycin-Resistant Enterococcus (VRE) or Methicillin-Resistant Staphylococcus aureus (MRSA) Bacteremia

Background. Multi-drug resistant bacteria are a growing concern in healthcare. Daptomycin is being used with increasing frequency in the treatment of vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) bacteremias in hemodialysis (HD) patients. Thrice-weekly dosing of daptomycin in this population would allow for coordination of dosing with common outpatient HD schedules. The aim of this study is to determine if thrice-weekly dosing of daptomycin is equivalent to dosing every 48 hours in patients receiving chronic intermittent hemodialysis. Equivalence will be assessed with regard to microbiological cure, clinical cure, hospital length of stay, and mortality. Methods. All patients with positive blood cultures who received at least one dose of daptomycin between January 1st 2009 and December 31st 2010 at Indiana University Health Methodist and University Hospitals were identified. Adult patients with end-stage renal disease on a stable thrice-weekly hemodialysis regimen, confirmed VRE or MRSA bacteremia, and at least three doses of inpatient daptomycin therapy were enrolled in the study. Results. Twelve patients met criteria for inclusion in this study. Nine received daptomycin every 48 hours for the treatment of bacteremia, and three received daptomycin thrice-weekly after dialysis. There was no difference in time to clearance of blood cultures between the Q48H and thrice-weekly groups (2.11±2.15 days vs. 4.33±4.16 days; p=0.241).Length of hospital stay was not statistically significantly different between the two groups (22.8 days vs. 14.9 days; p=0.065).Conclusions. Thrice-weekly dosing of daptomycin may be effective for the treatment of bacteremia in hemodialysis patients.

Unmet Needs and Prospects for Oritavancin in the Management of Vancomycin-Resistant Enterococcal Infections

The treatment of infections caused by vancomycin-resistant enterococci (VRE) has become an important clinical challenge and compromises the care of critically ill patients. A striking increase in the frequency of nosocomial isolation of multidrug-resistant Enterococcus faecium has dramatically reduced the therapeutic alternatives because the majority of E. faecium isolates are resistant to ampicillin and vancomycin. Only 2 agents have US Food and Drug Administration approval for the treatment of VRE (E. faecium) infections, namely, linezolid and quinupristin/dalfopristin (Q/D). However, the use of these compounds in severe VRE infections is hampered by the lack of in vivo bactericidal activity, reports of therapeutic failures with monotherapy, a requirement for central venous access for administration (Q/D), and adverse-effect profile. The lipopeptide antimicrobial daptomycin has in vitro bactericidal activity against VRE; however, clinical use of this compound for VRE has not been well studied, and the reports of resistance emerging during therapy at the approved doses are worrisome. Tigecycline has in vitro bacteriostatic activity against VRE, but its clinical use for serious enterococcal infections is unclear due to low serum levels and static effect. Thus, current reliable therapies for VRE appear to be limited, and clinical data that use the above compounds are certainly scant. Oritavancin is an investigational semisynthetic glycopeptide with potent in vitro activity against VRE (both VanA and VanB phenotypes). Although review of the available preclinical data indicates that this compound used as a single agent is likely to have important limitations for the treatment of a severe VRE infection (ie, endocarditis), combination of oritavancin with other agents such as aminoglycosides may offer promise and deserves further investigation, as does use of oritavancin for less serious infections as monotherapy for vancomycin-susceptible and multidrug-resistant enterococci.

간호학생을 위한 웹기반 VRE 감염관리 교육프로그램의 개발 및 효과

Purpose: The purpose of this study was to develop a web-based education program on control vancomycin-resistant enterococci (VRE) infections and to identify the effects of the program on knowledge and performance of nursing students. Methods: The web-based VRE infection control education program was developed by using the network-based instructional systems design model. The nursing students in the experimental group could access this web-based education program at any time, and as many times as they wanted, during the clinical training period. Effects were evaluated by assessing knowledge and performance of VRE infection control measures during the clinical training period. Results: The contents of the education program included diagnosis, transmission, and treatment of VRE, contact precautions, hand washing, personal protective equipment, environment management, and quizzes. The lecture portion was filmed in a virtual screen studio using flash animation, video, and sound effects, and it was uploaded on an internet site. The knowledge and performance scores of the experimental group after using the education program were significantly higher than those of the control group. Conclusion: The results suggest that the web-based VRE infection control education program is an effective educational method to enhance knowledge and performance of VRE infection control measures.

Comparison of the Clinical Characteristics and Outcomes Associated with Vancomycin-Resistant Enterococcus faecalis and Vancomycin-Resistant E. faecium Bacteremia

In published studies, cohorts of patients with bacteremia due to vancomycin-resistant Enterococcus (VRE) have predominantly been infected with Enterococcus faecium. Little is known about the epidemiology and outcomes associated with bacteremia due to VR Enterococcus faecalis. A retrospective study of isolates obtained from January 2008 to October 2010 was conducted at Detroit Medical Center (DMC). Unique patients with blood cultures positive for VRE were reviewed. Outcomes were analyzed using logistic regression. During the study period, 105 cases of bacteremia due to VR E. faecalis and 197 cases of bacteremia due to VR E. faecium were identified. The mean age in the study cohort was 61.5 ± 15 years; 162 subjects (53.6%) were male. After controlling for a propensity score, bacteremia due to VR E. faecalis was associated with >2-fold-lower in-hospital mortality than bacteremia due to VR E. faecium. Interestingly, bacteremia due to VR E. faecalis was associated with longer hospital stay after VRE isolation, although total length of stay was similar for groups with VR E. faecalis and VR E. faecium. Bacteremia due to VR E. faecalis was associated with a >2-fold-lower risk for mortality than bacteremia due to VR E. faecium, possibly due to the availability of β-lactam therapeutics for treatment of VR E. faecalis.

Vancomycin‐resistant Enterococcus bacteremia: An evaluation of treatment with linezolid or daptomycin

Due to high rates of resistance and a limited number of efficacious antimicrobials for vancomycin-resistant Enterococcus (VRE), appropriate antibiotic selection is vital to treatment success. The purpose of this study was to assess clinical and microbiologic outcomes associated with the use of linezolid or daptomycin in the treatment of VRE bacteremia. A retrospective analysis of adult patients with VRE bacteremia between January 2004 and July 2009 was conducted at a tertiary care hospital in the United States. Clinical and microbiologic outcomes for both therapies were evaluated using multiple criteria. Of the 361 patients with VRE bacteremia identified, 201 were included in the study (linezolid group, n = 138; daptomycin group, n = 63). More patients in the daptomycin group had hematologic malignancies (33% vs 14%) or received liver transplants (13% vs 4%). There was no difference in clinical or microbiologic cure between the linezolid and daptomycin groups (74% vs 75% and 94% vs 94%, respectively). Recurrence was documented in 3% of linezolid patients vs 12% of daptomycin patients (P = 0.0321). Reinfection was noted in 1% of patients in the linezolid group vs 6% of patients in the daptomycin group (P not significant). The average length of stay (LOS) was 37 days for the linezolid group vs 40 days for the daptomycin group (P not significant). Overall mortality was 20%, occurring in 25/138 linezolid patients vs 15/63 daptomycin patients (P not significant). No differences in clinical or microbiologic cure rates, LOS, or mortality were identified between the groups. Various factors may have contributed to the significantly higher recurrence of VRE bacteremia in daptomycin patients. This study suggests that linezolid and daptomycin appear equally efficacious in the treatment of VRE bacteremia.

Genetic Basis for In Vivo Daptomycin Resistance in Enterococci

Daptomycin is a lipopeptide with bactericidal activity that acts on the cell membrane of enterococci and is often used off-label to treat patients infected with vancomycin-resistant enterococci. However, the emergence of resistance to daptomycin during therapy threatens its usefulness. We performed whole-genome sequencing and characterization of the cell envelope of a clinical pair of vancomycin-resistant Enterococcus faecalis isolates from the blood of a patient with fatal bacteremia; one isolate (S613) was from blood drawn before treatment and the other isolate (R712) was from blood drawn after treatment with daptomycin. The minimal inhibitory concentrations (MICs) of these two isolates were 1 and 12 μg per milliliter, respectively. Gene replacements were made to exchange the alleles found in isolate S613 with those in isolate R712. Isolate R712 had in-frame deletions in three genes. Two genes encoded putative enzymes involved in phospholipid metabolism, GdpD (which denotes glycerophosphoryl diester phosphodiesterase) and Cls (which denotes cardiolipin synthetase), and one gene encoded a putative membrane protein, LiaF (which denotes lipid II cycle-interfering antibiotics protein but whose exact function is not known). LiaF is predicted to be a member of a three-component regulatory system (LiaFSR) involved in the stress-sensing response of the cell envelope to antibiotics. Replacement of the liaF allele of isolate S613 with the liaF allele from isolate R712 quadrupled the MIC of daptomycin, whereas replacement of the gdpD allele had no effect on MIC. Replacement of both the liaF and gdpD alleles of isolate S613 with the liaF and gdpD alleles of isolate R712 raised the daptomycin MIC for isolate S613 to 12 μg per milliliter. As compared with isolate S613, isolate R712--the daptomycin-resistant isolate--had changes in the structure of the cell envelope and alterations in membrane permeability and membrane potential. Mutations in genes encoding LiaF and a GdpD-family protein were necessary and sufficient for the development of resistance to daptomycin during the treatment of vancomycin-resistant enterococci. (Funded by the National Institute of Allergy and Infectious Diseases and the National Institutes of Health.).

Bacterial flagellin stimulates Toll-like receptor 5-dependent defense against vancomycin-resistant Enterococcus infection.

Treatment of vancomycin-resistant Enterococcus (VRE) infections is limited by the paucity of effective antibiotics. Administration of broad-spectrum antibiotics promotes VRE colonization by down-regulating homeostatic innate immune defenses. Intestinal epithelial cells and Paneth cells express antimicrobial factors on direct or indirect stimulation of the Toll-like receptor (TLR)-myeloid differentiation factor 88-mediated pathway by microbe-derived molecules. Here, we demonstrate that the TLR5 agonist flagellin restores antibiotic-impaired innate immune defenses and restricts colonization with VRE. Flagellin stimulates the expression of RegIIIgamma, a secreted C-type lectin that kills gram-positive bacteria, including VRE. Systemic administration of flagellin induces RegIIIgamma expression in intestinal epithelial cells and Paneth cells along the entire length of the small intestine. Induction of RegIIIgamma requires TLR5 expression in hematopoietic cells and is dependent on interleukin 22 expression. Systemic administration of flagellin to antibiotic-treated mice dramatically reduces VRE colonization. By enhancing mucosal resistance to multidrug-resistant organisms, flagellin administration may provide a clinically useful approach to prevent infections in patients treated with broad-spectrum antibiotics.