Pharmacodynamic Analysis of Daptomycin-treated Enterococcal Bacteremia: It Is Time to Change the Breakpoint

State-of-the-Art Review: Persistent Enterococcal Bacteremia

Persistent enterococcal bacteremia is a commonly encountered and morbid syndrome without a strong evidence base for optimal management practices. Here we highlight reports on the epidemiology of enterococcal bacteremia to better describe and define persistent enterococcal bacteremia, discuss factors specific to Enterococcus species that may contribute to persistent infections, and describe a measured approach to diagnostic and therapeutic strategies for patients with these frequently complicated infections. The diagnosis of persistent enterococcal bacteremia is typically clinically evident in the setting of repeatedly positive blood culture results; instead, the challenge is to determine in an accurate, cost-effective, and minimally invasive manner whether any underlying nidus of infection (eg, endocarditis or undrained abscess) is present and contributing to the persistent bacteremia. Clinical outcomes for patients with persistent enterococcal bacteremia remain suboptimal. Beyond addressing host immune status if relevant and pursuing source control for all patients, management decisions primarily involve the selection of the proper antimicrobial agent(s). Options for antimicrobial therapy are often limited in the setting of intrinsic and acquired antimicrobial resistance among enterococcal clinical isolates. The synergistic benefit of combination antimicrobial therapy has been demonstrated for enterococcal endocarditis, but it is not clear at present whether a similar approach will provide any clinical benefit to some or all patients with persistent enterococcal bacteremia.

Global impact of antibacterial resistance in patients with hematologic malignancies and hematopoietic cell transplant recipients

Patients with hematologic malignancies and hematopoietic cell transplant (HCT) recipients are at high risk of developing bacterial infections. These patients may suffer severe consequences from these infections if they do not receive immediate effective therapies, and thus are uniquely threatened by antimicrobial-resistant bacteria. Here, we outline how the emergence of specific resistant bacteria threatens the effectiveness of established approaches to prevent and treat infections in this population. The emergence of fluoroquinolone resistance among Enterobacterales and viridans group streptococci may decrease the effectiveness of fluoroquinolone prophylaxis during neutropenia. The emergence of Enterobacterales that produce extended-spectrum β-lactamases or carbapenemases and of increasingly resistant Pseudomonas aeruginosa may result in neutropenic patients experiencing delayed time to active antibacterial therapy, and consequently worse clinical outcomes. The ability to select targeted antibacterial therapies after the availability of susceptibility data may be limited in patients infected with metallo-β-lactamase-producing Enterobacterales and difficult-to-treat P. aeruginosa. Vancomycin-resistant enterococci and Stenotrophomonas maltophilia can cause breakthrough infections in patients already being treated with broad-spectrum β-lactam antibiotics. Resistance can also limit the ability to provide oral stepdown antibacterial therapy for patients who could otherwise be discharged from hospitalization. We also outline strategies that have the potential to mitigate the negative impact of antimicrobial resistance, including interventions based on active screening for colonization with resistant bacteria and the use of novel rapid diagnostic assays. Additional research is needed to better understand how these strategies can be leveraged to combat the emerging crisis of antimicrobial resistance in patients with hematologic malignancies and HCT recipients.

Therapeutics for Vancomycin-Resistant Enterococcal Bloodstream Infections

Vancomycin-resistant enterococci (VRE) are common causes of bloodstream infections (BSIs) with high morbidity and mortality rates. They are pathogens of global concern with a limited treatment pipeline. Significant challenges exist in the management of VRE BSI, including drug dosing, the emergence of resistance, and the optimal treatment for persistent bacteremia and infective endocarditis. Therapeutic drug monitoring (TDM) for antimicrobial therapy is evolving for VRE-active agents; however, there are significant gaps in the literature for predicting antimicrobial efficacy for VRE BSIs. To date, TDM has the greatest evidence for predicting drug toxicity for the three main VRE-active antimicrobial agents daptomycin, linezolid, and teicoplanin. This article presents an overview of the treatment options for VRE BSIs, the role of antimicrobial dose optimization through TDM in supporting clinical infection management, and challenges and perspectives for the future.

Treatment decisions in VRE bacteraemia: a survey of infectious diseases pharmacists

Background

VRE infections increased in 2020. High-dose daptomycin (≥10 mg/kg) has shown mortality benefit over other regimens, though daptomycin resistance is increasing. Limited data exist on the practice patterns of ID pharmacists for VRE bloodstream infections (VRE BSIs).

Objectives

To describe practice patterns for VRE BSI in ID pharmacists.

Methods

A 22-question REDCap survey was distributed to ID pharmacist members of the American College of Clinical Pharmacy (ACCP) Infectious Diseases Practice and Research Network (ID PRN) via e-mail listserv. The survey was distributed on 7 April 2022 and remained open for 4 weeks.

Results

Sixty-eight pharmacists responded. All pharmacists completed additional training or certification in infectious diseases past their PharmD, and most (70.5%) had been practising for 10 years or less. Pharmacists at academic medical centres (80.0%) were more likely (P = 0.001) to have implemented the updated CLSI breakpoints than pharmacists at other types of institutions (55.2%). Daptomycin was the preferred drug for VRE BSI (92.6%), with 10 mg/kg (72.1%) being the preferred dose. Adjusted body weight was the most common weight (61.2%) used for obese patients. Fourteen days (76.1%) was the most common treatment duration for VRE BSI. Pharmacists defined persistent VRE BSI as 5 days (68.7%) after first blood culture.

Conclusions

ID pharmacists overwhelmingly selected high-dose daptomycin for VRE BSI. There were variations in practice and response rate when selecting combination therapy, managing persistent bacteraemia, and treating patients with high daptomycin MICs or previous exposure to daptomycin.

Off-label use versus formal recommendations of conventional and novel antibiotics for the treatment of infections caused by multidrug-resistant bacteria

The infections caused by multidrug- and extensively drug-resistant (MDR, XDR) bacteria, including Gram-positive cocci (GPC, including methicillin-resistant Staphylococcus aureus, MDR-Streptococcus pneumoniae and vancomycin-resistant enterococci) and Gram-negative bacilli (GNB, including carbapenem-resistant [CR] Enterobacterales, CR-Pseudomonas aeruginosa and XDR/CR-Acinetobacter baumannii complex) can be quite challenging for physicians with respect to treatment decisions. Apart from complicated urinary tract and intra-abdominal infections (cUTIs, cIAIs), bloodstream infections and pneumonia, these difficult-to-treat bacteria also cause infections at miscellaneous sites (bones, joints, native/prosthetic valves and skin structures, etc.). Antibiotics like dalbavancin, oritavancin, telavancin and daptomycin are currently approved for the treatment of acute bacterial skin and skin structural infections (ABSSSIs) caused by GPC. Additionally, ceftaroline, linezolid and tigecycline have been formally approved for the treatment of community-acquired pneumonia and ABSSSI. Cefiderocol and meropenem-vaborbactam are currently approved for the treatment of cUTIs caused by XDR-GNB. The spectra of ceftazidime-avibactam and imipenem/cilastatin-relebactam are broader than that of ceftolozane-tazobactam, but these three antibiotics are currently approved for the treatment of hospital-acquired pneumonia, cIAIs and cUTIs caused by MDR-GNB. Clinical investigations of other novel antibiotics (including cefepime-zidebactam, aztreonam-avibactam and sulbactam-durlobactam) for the treatment of various infections are ongoing. Nevertheless, evidence for adequate antibiotic regimens against osteomyelitis, arthritis and infective endocarditis due to several GPC and MDR-GNB is still mostly lacking. A comprehensive review of PubMed publications was undertaken and the formal indications and off-label use of important conventional and novel antibiotics against MDR/XDR-GPC and GNB isolates cultured from miscellaneous sites are presented in this paper.

The impact of daptomycin therapeutic drug monitoring on clinical outcomes: a systematic review

AIM

Daptomycin therapeutic drug monitoring (TDM) is a potentially valuable intervention for a relatively new drug. The aim of this study was to determine whether daptomycin TDM, including dose adjustment where necessary, improves the clinical outcomes of adult patients with Gram-positive infections.

METHODS

A systematic review of English-language studies in MEDLINE (Ovid MEDLINE and Epub Ahead of Print, In-process, In-Data-Review & Other Non-Indexed Citations, Daily and Versions), EMBASE via OVID, Cochrane Central Register of Controlled Trials via the OVID platform, Scopus and Web of Science online databases was performed and conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. There was no discrimination on study type or time of publication.

STUDY SELECTION

Adults (age ≥18 years) with a Gram-positive infection requiring treatment with daptomycin who received TDM, with subsequent reporting of serum concentrations and dose adjustment where necessary, were included.

RESULTS

In total, 2869 studies were identified, of which nine met the inclusion criteria. No studies of daptomycin TDM including a relevant control arm have been published to date. All of the included studies were single-arm observational cohort studies. Broad heterogeneity was observed between the studies in terms of included pathogens, infection types, daptomycin TDM practices, reported clinical outcomes, and reporting of potential confounders.

CONCLUSIONS

No studies exploring the efficacy of routine daptomycin TDM on patient-centred outcomes in comparison with fixed dosing regimens have been published to date. This represents a key knowledge gap as opposed to an inherent lack of efficacy. Further well-designed, comparative studies are required to determine the role of daptomycin TDM in patients with Gram-positive infections.

The Combination of Daptomycin with Fosfomycin is More Effective than Daptomycin Alone in Reducing Mortality of Vancomycin-Resistant Enterococcal Bloodstream Infections: A Retrospective, Comparative Cohort Study

INTRODUCTION

High-dose daptomycin-based combinations are recommended for vancomycin-resistant Enterococcus (VRE) bloodstream infection (BSI). Preclinical data have shown a synergistic effect of daptomycin/fosfomycin combinations against VRE. However, clinical studies comparing daptomycin monotherapy with daptomycin/fosfomycin combinations are unavailable.

METHODS

An observational study of VRE-BSI was performed between 2010-2021 on patients receiving daptomycin monotherapy (≥ 8 mg/kg) or daptomycin combined with intravenous fosfomycin. Patients treated with concomitant β-lactam combinations were excluded. The primary outcome was in-hospital mortality. Outcomes were analyzed using multivariable logistic regression and augmented inverse probability weighting (AIPW) analyses.

RESULTS

Among 224 patients, 176 received daptomycin monotherapy, and 48 received fosfomycin combinations. The median daptomycin and fosfomycin doses were 9.8 mg/kg and 12 g/day, respectively. In-hospital mortality was 77.3% and 47.9% in the daptomycin monotherapy and fosfomycin combination groups (P < 0.001), respectively. Multivariable logistic regression analysis predicted lower mortality with fosfomycin combination treatment (adjusted odds ratio, 0.35; 95% confidence interval (CI), 0.17-0.73; P = 0.005). AIPW demonstrated a 17.8% reduced mortality with fosfomycin combinations (95% CI, - 30.6- - 4.9%; P = 0.007). The survival benefit was significant, especially among patients with a lower Pitt bacteremia score or fosfomycin minimum inhibitory concentration (MIC) ≤ 64 mg/l. Fosfomycin combination resulted in higher hypernatremia (10.4% vs. 2.8%, P = 0.04) and hypokalemia (33.3% vs. 15.3%, P = 0.009) compared to daptomycin monotherapy.

CONCLUSION

The combination of high-dose daptomycin with fosfomycin improved the survival rate of patients with VRE-BSI compared to daptomycin alone. The benefit of the combination was most pronounced for VRE with fosfomycin MIC ≤ 64 mg/l and for patients with a low Pitt bacteremia score.

Successful Treatment of Vancomycin-Resistant Enterococcus species Bone and Joint Infection with Daptomycin Plus Beta Lactam Agents

Bone and joint infections (BJI) caused by vancomycin-resistant Enterococcus spp. (VRE) are difficult to treat due to limited antibiotic options. Although linezolid can be used for VRE treatment, it is often discontinued due to time-dependent bone marrow suppression. Daptomycin, a lipopeptide antibiotic agent with rapid bactericidal activity, is another available therapeutic option for VRE infections. We report a case of VRE BJI successfully treated with a high dose of daptomycin plus β-lactam agents. An 84-year-old man received linezolid for the treatment of VRE BJI. After 2 weeks of therapy, the patient experienced bleeding events associated with linezolid-induced bone marrow toxicity and linezolid was discontinued. Next, high-dose daptomycin therapy combined with a β-lactam agent was selected to treat the remaining VRE BJI. During daptomycin treatment, microbiological eradication was achieved, and the patient clinically improved without evidence of adverse events. We highlight the need for daptomycin use for the treatment of VRE infections, especially in cases where linezolid is ineffective.

A High Daptomycin Dose Is Associated with Better Bacterial Clearance in Infections Caused by Vancomycin-Resistant Enterococcus faecium Regardless of Daptomycin Minimum Inhibitory Concentration in a Rat Infective Endocarditis Model

A high daptomycin dose has been suggested for treating vancomycin-resistant Enterococcus faecium (VREf) infections. However, even a 12 mg/kg daptomycin dose might be insufficient for treating VREf with high daptomycin minimum inhibitory concentrations (MICs). Additionally, animal pharmacodynamic and infection models to confirm the efficacy of 12 mg/kg daptomycin are lacking. Male Wistar rats were used for pharmacokinetic profiling and for the development of an infective endocarditis (IE) model. Daptomycin-susceptible dose-dependent VREf (DSE) (MIC of 0.5 mg/L) and daptomycin nonsusceptible VREf (DNSE) (MIC of 8 mg/L) were used for the IE models. The bacterial load of vegetation was the primary outcome and was evaluated after 3 days of daptomycin treatment. Daptomycin administered subcutaneously (s.c.) at 45 and 90 mg/kg, which corresponded to maximum serum concentrations (Cmax) of 122.6 mg/L and 178.5 mg/L, respectively, was equivalent to doses of 8 mg/kg and 12 mg/kg, respectively, in humans. The Cmax/MIC value was correlated with the bacterial load of vegetation after treatment (r = -0.88, P < 0.001). The 90 mg/kg s.c. group showed a significantly lower bacterial load of vegetation (log10 CFU/g) than the 45 mg/kg s.c. group against DSE (0 versus 4.75, P < 0.001) and DNSE (5.12 versus 6.98, P = 0.002). The 90 mg/kg s.c. group did not sterilize the vegetation against DNSE. Although the human equivalent dose of 12 mg/kg daptomycin was more effective than the smaller dose in reducing the bacterial load in DSE and DNSE IE, the dose could not sterilize the vegetation during a DNSE treatment. Further treatment strategies by which to manage severe VREf infections, especially at high daptomycin MICs, are urgently needed. IMPORTANCE Using a rat IE model with pharmacokinetic analysis, the treatment response of VREf IE was found to be daptomycin dose-dependent, presented as Cmax/MIC or as the 24 h area under the concentration-time curve (AUC0-24)/MIC. Daptomycin 90 mg/kg s.c. significantly reduced the bacterial load against DSE and DNSE. It also showed significant activity against DSE and DNSE, compared to 45 mg/kg s.c. Although daptomycin 90 mg/kg can eradicate the bacterial load after 3 days of treatment against DSE, eradication cannot be achieved with 90 mg/kg daptomycin against DNSE.

Daptomycin area under the curve to minimum inhibitory concentration ratio by broth microdilution for predicting the outcome of vancomycin-resistant Enterococcus bloodstream infection

OBJECTIVES

Different methods are used to determine the minimum inhibitory concentration (MIC) for daptomycin. The threshold is unknown for the free drug area under the concentration-time curve to MIC ratio (fAUC/MIC) of daptomycin using broth microdilution (BMD) to predict outcome of vancomycin-resistant enterococcus (VRE) bacteremia. The MIC testing method which is best for predicting the outcome remains unclear.

METHODS

This is a retrospective cohort study. The inclusion criterion was VRE bacteremia treated with ≥ 8 mg/kg of daptomycin. As we aimed to compare different daptomycin MIC testing methods for predicting the clinical outcome of VRE bacteremia, the inclusion criteria included the availability of MIC values for BMD, Etest, and automated antimicrobial susceptibility testing (AST). The primary end point was 28-day mortality. The fAUC/MIC was dichotomized using classification and regression tree analysis for predicting survival.

RESULTS

A total of 393 patients were included; 215 survived and 178 died. In the multivariable logistic model for predicting mortality, the dichotomized fAUC/MICs for Etest and AST were 0.508 and 0.065 times as probable, respectively, as that for BMD to minimize information loss. An fAUC/MIC > 75.07 for BMD significantly predicted lower mortality (adjusted odds ratio, 0.53, 95% confidence interval, 0.30-0.95; P = 0.03) after adjusting for underlying disease and bacteremia severity. Using Monte Carlo simulation, none of the doses had a probability of target attainment of ≥ 50% with an MIC of ≥ 2 mg/L.

CONCLUSION

The dichotomized threshold for fAUC/MIC for BMD was the best predictor of mortality. An fAUC/MIC > 75.07 for BMD independently predicted better survival.

Daptomycin Physiology-Based Pharmacokinetic Modeling to Predict Drug Exposure and Pharmacodynamics in Skin and Bone Tissues

BACKGROUND AND OBJECTIVE

Daptomycin has been recommended in the treatment of bone and joint infection. Previous work showed that the approved dosage of daptomycin may be insufficient to achieve optimal exposure in patients with bone and joint infection. However, those studies assumed that bone exposure was similar to steady-state daptomycin-free plasma concentrations. We sought to establish a physiologically based pharmacokinetic (PBPK) model of daptomycin to describe the dynamics of daptomycin disposition in bone and skin tissue.

METHODS

A PBPK model of daptomycin was built using PK-Sim^®. Daptomycin concentrations in plasma and bone were obtained from three previously published studies. Physicochemical drug characteristics, mass balance, anthropometrics, and experimental data were used to build and refine the PBPK model. Internal validation of the PBPK model was performed using the usual diagnostic plots. The final PBPK model was then used to run simulations with doses of 6, 8, 10, and 12 mg/kg/24 h. Pharmacokinetic profiles were simulated in 1000 subjects and the probabilities of target attainment for the area under the concentration-time curve over the bacterial minimum inhibitory concentration were computed in blood, skin, and bone compartments.

RESULTS

The final model showed a good fit of all datasets with an absolute average fold error between 0.5 and 2 for all pharmacokinetic quantities in blood, skin and bone tissues. Results of dosing simulations showed that doses ≥10 mg/kg should be used in the case of bacteremia caused by Staphylococcus aureus with a minimum inhibitory concentration >0.5 mg/L or Enterococcus faecalis with a minimum inhibitory concentration >1 mg/L, while doses ≥12 mg/kg should be used in the case of bone and joint infection or complicated skin infection. When considering a lower minimum inhibitory concentration, doses of 6-8 mg/kg would likely achieve a sufficient success rate. However, in the case of infections caused by E. faecalis with a minimum inhibitory concentration >2 mg/L, a higher dosage and combination therapy would be necessary to maximize efficacy.

CONCLUSIONS

We developed the first daptomycin PBPK/pharmacodynamic model for bone and joint infection, which confirmed that a higher daptomycin dosage is needed to optimize exposure in bone tissue. However, such higher dosages raise safety concerns. In this setting, therapeutic drug monitoring and model-informed precision dosing appear necessary to ensure the right exposure on an individual basis.

Daptomycin Population Pharmacokinetics in Patients Affected by Severe Gram-Positive Infections: An Update

Daptomycin pharmacokinetics may not depend on renal function only and it significantly differs between healthy volunteers and severely ill patients. Herein, we propose a population pharmacokinetics model based on 424 plasma daptomycin concentrations collected from 156 patients affected by severe Gram-positive infections during a routine therapeutic drug monitoring protocol. Model building and validation were performed using NONMEM 7.2 (ICON plc), Xpose4 and Perl-speaks-to-NONMEM. The final pop-PK model was a one-compartment first-order elimination model, with a 2.7% IIV for drug clearance (Cl), influence of creatinine clearance on drug clearance and of sex on distribution volume. After model validation, we simulated 10,000 patients with the Monte-Carlo method to predict the efficacy and tolerability of different daptomycin daily dosages. For the most common 6 mg/kg daily dose, the simulated probability of overcoming the toxic minimum concentration (24.3 mg/L) was 14.8% and the efficacy (expressed as a cumulative fraction of response) against methicillin-resistant S. aureus, S. pneumoniae and E. faecium was 95.77%, 99.99% and 68%, respectively. According to the model-informed precision dosing paradigm, pharmacokinetic models such as ours could help clinicians to perform patient-tailored antimicrobial dosing and maximize the odds of therapy success without neglecting toxicity risks.

Influence of daptomycin doses on the outcomes of VRE bloodstream infection treated with high-dose daptomycin

OBJECTIVES

The CLSI recommended high-dose daptomycin (8-12 mg/kg) for treating Enterococcus faecium bloodstream infections (BSI). The current study was designed to determine the safety and efficacy of increasing the daptomycin dose for VRE BSI patients receiving ≥8 mg/kg.

METHODS

We conducted a multicentre prospective observational study of patients who received a ≥8 mg/kg dose of daptomycin for treatment of VRE BSI. The primary outcome was 28 day mortality.

RESULTS

A total of 661 patients were included. The 28 day mortality rate was 45.1%. The survivors received higher doses of daptomycin than non-survivors (10.1 versus 9.8 mg/kg; P < 0.001). An increase in the daptomycin dose independently predicted lower mortality [adjusted OR (aOR) = 0.85; 95% CI = 0.73-0.99; P = 0.03]. Eighty-six survivors (23.7%) and 43 non-survivors (14.4%) received a ≥11 mg/kg dose of daptomycin (P = 0.003). The 8 to <11 and ≥11 mg/kg doses of daptomycin differed in the 28 day mortality in the higher MIC group (≥2 mg/L) (49.4% versus 33.3%; P = 0.004), but not in the lower MIC group (≤1 mg/L) (29.3% versus 29.4%; P = 0.99). A dose of ≥11 mg/kg was associated with a higher (3.9%) rate of highly elevated creatine kinase (>2000 U/L) compared with 1.1% with 8 to <11 mg/kg (P = 0.04).

CONCLUSIONS

The efficacy of daptomycin is dose dependent. A high daptomycin dose, especially at ≥11 mg/kg, improved survival in patients with VRE BSI, but was associated with highly elevated creatine kinase. We recommend a ≥11 mg/kg dose of daptomycin be considered for treatment of VRE BSI, particularly for isolates with higher MICs.

Implementation and Comparison of Two Pharmacometric Tools for Model-Based Therapeutic Drug Monitoring and Precision Dosing of Daptomycin

Daptomycin is a candidate for therapeutic drug monitoring (TDM). The objectives of this work were to implement and compare two pharmacometric tools for daptomycin TDM and precision dosing. A nonparametric population PK model developed from patients with bone and joint infection was implemented into the BestDose software. A published parametric model was imported into Tucuxi. We compared the performance of the two models in a validation dataset based on mean error (ME) and mean absolute percent error (MAPE) of individual predictions, estimated exposure and predicted doses necessary to achieve daptomycin efficacy and safety PK/PD targets. The BestDose model described the data very well in the learning dataset. In the validation dataset (94 patients, 264 concentrations), 21.3% of patients were underexposed (AUC_24h < 666 mg.h/L) and 31.9% of patients were overexposed (C_min > 24.3 mg/L) on the first TDM occasion. The BestDose model performed slightly better than the model in Tucuxi (ME = -0.13 ± 5.16 vs. -1.90 ± 6.99 mg/L, p < 0.001), but overall results were in agreement between the two models. A significant proportion of patients exhibited underexposure or overexposure to daptomycin after the initial dosage, which supports TDM. The two models may be useful for model-informed precision dosing.

The Global Prevalence of Daptomycin, Tigecycline, and Linezolid-Resistant Enterococcus faecalis and Enterococcus faecium Strains From Human Clinical Samples: A Systematic Review and Meta-Analysis

Background and Aim: The predominant species of the Enterococcus, Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) cause great variety of infections. Therefore, the expansion of antimicrobial resistance in the Enterococcus is one of the most important global concerns. This study was conducted to investigate the prevalence of resistance to linezolid, tigecycline, and daptomycin among enterococcal strains isolated from human clinical specimens worldwide.

Methods: Several databases including Web of Science, EMBASE, and Medline (via PubMed), were carefully searched and reviewed for original research articles available in databases and published between 2000 and 2020. A total of 114 studies worldwide that address E. faecalis and E. faecium resistance to linezolid, tigecycline, and daptomycin were analyzed by STATA software.

Results: The overall prevalence of antibiotic-resistant E. faecalis and E. faecium was reported to be 0.9 and 0.6%, respectively. E. faecalis and E. faecium were more resistant to the linezolid (2.2%) and daptomycin (9%), respectively. The prevalence of tigecyline-resistant E. facium (1%) strains was higher than E. faecalis strains (0.3%). Accordingly, the prevalence of linezolid-resistant E. faecalis was higher in Asia (2.8%), while linezolid-resistant E. faecium was higher in the America (3.4%). Regarding tigecycline-resistance, a higher prevalence of E. faecalis (0.4%) and E. faecium (3.9%) was reported in Europe.

Conclusion: In conclusion, this meta-analysis shows that there is an emerging resistance in Enterococcus strains. Despite the rising resistance of enterococci to antibiotics, our results demonstrate that tigecycline, daptomycin, and linezolid can still be used for the treatment of enterococcal infections worldwide.

Daptomycin versus Glycopeptides for the Treatment of Enterococcus faecium Bacteraemia: A Cohort Study

Background: Ampicillin resistant and glycopeptide susceptible Enterococcus faecium bloodstream infection (GSEF-BSI) incidence has risen. However, the treatment of choice remains unknown. Daptomycin use for the treatment of enterococcal infections has increased, despite effectiveness and safety concerns. The objective was to compare the effectiveness and safety of daptomycin and glycopeptides in the treatment of GSEF-BSI. Methods: This was a single-centre, retrospective observational cohort study performed at Hospital del Mar (Barcelona, Spain), from January 2006–May 2018. The primary outcome was clinical cure at the end of the therapy, and secondary outcomes included 14-day, 30-day, in-hospital mortality, and length of stay. Results: From a total of 192 patients with GSEF-BSI, 54 (28.1%) were treated with glycopeptides and 17 (8.9%) with daptomycin. Patients treated with daptomycin presented a lower clinical cure than patients treated with glycopeptides (58.8% vs. 83.3%, RR 0.416 (95% CI 0.189–0.915)). After controlling for confounding variables by means of multivariate analysis the significative difference was confirmed (aOR 4.313, 95% CI, 1.053–17.660). The need for treatment discontinuation due to adverse events was similar. Conclusions: Patients with GSEF-BSI treated with glycopeptides showed a higher clinical cure than those treated with daptomycin.

Population pharmacokinetics of daptomycin in patients with bone and joint infection: minimal effect of rifampicin co-administration and confirmation of a sex difference

BACKGROUND

Daptomycin is increasingly used in the treatment of bone and joint infection (BJI), but its pharmacokinetics (PK) and dosage requirements have not been thoroughly investigated in this indication. Daptomycin may be co-administered with rifampicin, which raises questions about a potential drug interaction.

OBJECTIVES

To investigate the population PK and dosage requirements of daptomycin in patients with BJI, and examine the influence of rifampicin co-administration.

METHODS

A population approach was used to analyse PK data from patients who received daptomycin in our regional reference for BJI. We examined the influence of available covariates, including rifampicin co-administration on daptomycin PK. Simulations performed with the final model investigated the influence of dosages and covariates on PTA for both efficacy and safety.

RESULTS

A total of 1303 daptomycin concentrations from 183 patients were analysed. A two-compartment model best described the data. Significant intra-individual variability was observed. Daptomycin clearance was influenced by renal function and sex, with females having a 26% lower typical clearance than males. Central volume of distribution (V1) was influenced by body weight, age, sex and rifampicin co-administration. Typical V1 was 11% lower in patients who were co-administered rifampicin. In PK/PD simulations, sex influenced the probability of AUC24/MIC target attainment, while rifampicin had a marginal effect.

CONCLUSIONS

A daptomycin dosage of 8 mg/kg/24 h in women and 10 mg/kg/24 h in men should optimize efficacy but may lead to excessive trough concentrations in many patients, especially in women. Therapeutic drug monitoring appears necessary for precision dosing of daptomycin.

High-Dose Daptomycin and Clinical Applications

OBJECTIVE

To evaluate evidence for high-dose daptomycin (doses ≥ 8 mg/kg/d).

DATA SOURCES

A PubMed/MEDLINE literature search was performed (January 2000 to December 2020) using the search terms daptomycin, high dose, and dosing. Review article references and society guidelines were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Clinical trials, observational studies, retrospective studies, meta-analyses, and systematic reviews reporting on high-dose daptomycin were included.

DATA SYNTHESIS

Experimentally, daptomycin outperforms other antimicrobials for high inoculum and biofilm-associated infections. Clinically, high-dose daptomycin is supported as salvage and first-line therapy for endocarditis and bacteremia, primarily when caused by methicillin-resistant Staphylococcus aureus (when vancomycin minimum inhibitory concentration is >1 mg/L) and Enterococcus. High-dose daptomycin appears effective for osteomyelitis and central nervous system infections, although comparative studies are lacking. High dosing in renal replacement therapy requires considering clearance modality to achieve exposures like normal renal function. Weight-based dosing in obesity draws concern for elevated exposures, although high doses have not been evaluated kinetically in obesity. Some data show benefits of high doses in overweight populations. Burn patients clear daptomycin more rapidly, and high doses may only achieve drug exposures similar to standard doses (6 mg/kg).

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review analyzes the efficacy and safety of high-dose daptomycin in serious gram-positive infections. Discussion of specific infectious etiologies and patient populations should encourage clinicians to evaluate their daptomycin dosing standards.

CONCLUSIONS

The efficacy of high-dose daptomycin and limited safety concerns encourage clinicians to consider high-dose daptomycin more liberally in severe gram-positive infections.

Development of Daptomycin Susceptibility Breakpoints for Enterococcus faecium and Revision of the Breakpoints for Other Enterococcal Species by the Clinical and Laboratory Standards Institute

Daptomycin is one of the few treatment options for infections caused by enterococci that are resistant to ampicillin and vancomycin, such as vancomycin-resistant Enterococcus faecium. The emergence and clinical significance of daptomycin-resistant enterococci and evolving microbiologic, pharmacokinetic-pharmacodynamic, and clinical data indicated that the pre-2019 Clinical and Laboratory Standards Institute (CLSI) susceptible-only breakpoint of ≤4 μg/mL for daptomycin and enterococci was no longer appropriate. After analyzing data that are outlined in this article, the CLSI Subcommittee on Antimicrobial Susceptibility Testing established new breakpoints for daptomycin and enterococci. For E. faecium, a susceptible dose-dependent (SDD) breakpoint of ≤4 μg/mL was established based on an increased dosage of 8-12 mg/kg/day (≥8 μg/mL-resistant). CLSI suggests infectious diseases consultation to guide daptomycin use for the SDD category. For Enterococcus faecalis and other enterococcal species, revised breakpoints of ≤2 μg/mL-susceptible, 4 μg/mL-intermediate, and ≥8 μg/mL-resistant were established based on a standard dosage of 6 mg/kg/day.

Clinical Pharmacokinetics of Daptomycin

Due to the low level of resistance observed with daptomycin, this antibiotic has an important place in the treatment of severe Gram-positive infections. It is the first-in-class of the group of calcium-dependent, membrane-binding lipopeptides, and is a cyclic peptide constituted of 13 amino acids and an n-decanoyl fatty acid chain. The antibacterial action of daptomycin requires its complexation with calcium. Daptomycin is not absorbed from the gastrointestinal tract and needs to be administered parenterally. The distribution of daptomycin is limited (volume of distribution of 0.1 L/kg in healthy volunteers) due to its negative charge at physiological pH and its high binding to plasma proteins (about 90%). Its elimination is mainly renal, with about 50% of the dose excreted unchanged in the urine, justifying dosage adjustment for patients with renal insufficiency. The pharmacokinetics of daptomycin are altered under certain pathophysiological conditions, resulting in high interindividual variability. As a result, therapeutic drug monitoring of daptomycin may be of interest for certain patients, such as intensive care unit patients, patients with renal or hepatic insufficiency, dialysis patients, obese patients, or children. A target for the ratio of the area under the curve to the minimum inhibitory concentration > 666 is usually recommended for clinical efficacy, whereas in order to limit the risk of undesirable muscular effects the residual concentration should not exceed 24.3 mg/L.

A Pharmacokinetic-Pharmacodynamic Analysis to Dose Optimize Daptomycin in Vancomycin-Resistant Enterococcus faecium: Is the Answer Fixed Dosing or Lowering Breakpoints?

BACKGROUND

The optimal daptomycin dose for vancomycin-resistant Enterococcus faecium remains unclear. Dosing of 8 to 12 mg/kg/d has been recommended to improve outcomes, but literature suggests fixed dosing may improve methicillin-resistant Staphylococcus aureus bacteremia pharmacodynamic (PD) targets.

OBJECTIVE

This study sought to evaluate weight-based versus fixed dosing of daptomycin based on pharmacokinetic and PD (PK-PD) targets in vancomycin-resistant E faecium bacteremia.

METHODS

PK-PD analyses were conducted using previously published PK models for daptomycin. Probability of target attainment (PTA) was assessed for 8 to 12 mg/kg/d and various fixed doses. The percentage of simulated participants who achieved a free area under the concentration-time curve from 0 to 24 hours to minimum inhibitory concentration ratio (fAUC_0-24/MIC) >27.43 for susceptible dose-dependent (SDD) MICs and the probability of a minimum concentration (C_min) > 24.3 mg/L were calculated.

RESULTS

At MICs ≤2 mg/L, fixed doses had the best overall PTA. At the SDD breakpoint of 4 mg/L, all weight-based doses had <60% PTA. A fixed dose of 1500 mg/d was necessary for >/= 90% PTA at higher MICs considered SDD; however, this dose had elevated risks of C_min ≥24.3 mg/L.

CONCLUSION AND RELEVANCE

Fixed doses were more likely to achieve a fAUC/MIC of 27.43 than weight-based doses up to 12 mg/kg/d. However, fixed doses necessary for 90% PTA against SDD isolates with higher MICs were associated with elevated risks of toxicity. A reevaluation of Clinical Laboratory Standards Institute breakpoints may need to be considered, with an emphasis on lowering the SDD breakpoint to 1 mg/L.

How do I manage a patient with enterococcal bacteraemia?

BACKGROUND

Enterococcal bacteraemia (EB) is common, particularly in the nosocomial setting, and its management poses a challenge for clinicians and microbiologists.

OBJECTIVES

The aim was to summarize the more relevant features of EB and to provide a practical state-of-the-art on the topics that more directly affect its management.

SOURCES

Pubmed articles from inception to 31 May 2020.

CONTENT

The following topics are covered: epidemiological, clinical and microbiological characteristics and factors associated with prognosis of EB; diagnosis and work-up, including the use of echocardiography to rule out endocarditis; antibiotic management with special focus on antimicrobial resistance and complicated EB; and the role of infectious disease consultation and the use of bundles in EB. In addition, three clinical vignettes are presented to illustrate the practical application of the guidance provided, and major gaps in the current evidence supporting EB management are discussed.

IMPLICATIONS

EB is associated with large burdens of morbidity and mortality, particularly among fragile and immunosuppressed patients presenting complicated bacteraemia due to multidrug-resistant enterococci. Most cases of EB are caused by Enterococcus faecalis, followed by E. faecium. EB often presents as polymicrobial bacteraemia. Rapidly identifying patients at risk of EB is crucial for timely application of diagnostic techniques and empiric therapy. Early alert systems and rapid diagnostic techniques, such as matrix-assisted desorption ionization-time of flight mass spectrometry, especially if used together with infectious disease consultation within bundles, appear to improve management and prognosis of EB. Echocardiography is also key in the work-up of EB and should probably be more extensively used, although its exact indications in EB are still debated. Multidisciplinary approaches are warranted due to the complexity and severity of EB.

[Infections due to multidrug-resistant pathogens : Pathogens, resistance mechanisms and established treatment options]

The increase in resistant pathogens has long been a global problem. Complicated life-threatening infections due to multidrug-resistant pathogens (MRD) meanwhile occur regularly in intensive care medicine. An important and also potentially modifiable factor of the rapid spread of resistance is the irrational use of broad spectrum antibiotics in human medicine. In addition to many other resistance mechanisms, beta-lactamases play an important role in Gram-negative pathogens. They are not uncommonly the leading reason of difficult to treat infections and the failure of known routinely used broad spectrum antibiotics, such as cephalosporins, (acylamino)penicillins and carbapenems. Strategies for containment of MRDs primaríly target the rational use of antibiotics. In this respect interdisciplinary treatment teams, e.g. antibiotic stewardship (ABS) and infectious diseases stewardship (IDS) play a major role.

Daptomycin in the treatment of enterococcal bloodstream infections and endocarditis: a EUCAST position paper

SCOPE

This position paper describes the view adopted by EUCAST on the role of daptomycin in the treatment of serious infections caused by Enterococcus species.

BACKGROUND

High-dose daptomycin is considered effective in the treatment of enterococcal bloodstream infection (BSI) and endocarditis, although published clinical experience with the latter condition is limited.

METHODS

EUCAST reviewed the available published data on pharmacokinetics-pharmacodynamics (PK-PD), resistance selection, clinical efficacy and safety for the use of 10-12 mg/kg/day of daptomycin for these conditions, noting that the doses licensed by the European Medicines Agency are only 4-6 mg/kg/day, and only for infections caused by Staphylococcus aureus.

FINDINGS AND RECOMMENDATIONS

The PK-PD evidence shows that, even with doses of 10-12 mg/kg/day, it is not possible to treat infections caused by isolates at the upper end of the wild-type distributions of Enterococcus faecalis (with MICs of 4 mg/L) and E. faecium (with MICs of 4 or 8 mg/L). For this reason, and because there are ongoing issues with the reliability of laboratory testing, EUCAST lists daptomycin breakpoints for Enterococcus species as "IE"-insufficient evidence. EUCAST advises increased vigilance in the use of high-dose of daptomycin to treat enterococcal BSI and endocarditis. Additional PK-PD studies and prospective efficacy and safety studies of serious Enterococcal infections treated with high-dose daptomycin may permit the setting of breakpoints in the future.

Impact of Daptomycin Dose Exposure Alone or in Combination with β-Lactams or Rifampin against Vancomycin-Resistant Enterococci in an In Vitro Biofilm Model

Enterococcus faecium strains are commonly resistant to vancomycin and β-lactams. In addition, E. faecium often causes biofilm-associated infections and these infections are difficult to treat. In this context, we investigated the activity of dosing regimens using daptomycin (DAP) (8, 10, 12, and 14 mg/kg of body weight/day) alone and in combination with ceftaroline (CPT), ampicillin (AMP), ertapenem (ERT), and rifampin (RIF) against 2 clinical strains of biofilm-producing vancomycin-resistant Enterococcus faecium (VREfm), namely, strains S447 and HOU503, in an in vitro biofilm model. HOU503 harbors common LiaS and LiaR substitutions, whereas S447 lacks mutations associated with the LiaFSR pathway. MIC results demonstrated that both strains were susceptible to DAP and resistant to CPT, AMP, ERT, and RIF. The 168-h pharmacokinetic/pharmacodynamic (PK/PD) CDC biofilm reactor models (simulating human antibiotic exposures) were used with titanium and polyurethane coupons to evaluate the efficacy of antibiotic combinations. DAP 12 and 14 achieved bactericidal activity against S447 but lacked such effect against HOU503. Addition of ERT and RIF enhanced DAP activity, allowing DAP 8 and 10 plus ERT or RIF to produce bactericidal activity against both strains at 168 h. While DAP 8 and 10 plus CPT improved killing, they did not reach bactericidal reduction against S447. Combination of AMP, CPT, ERT, or RIF resulted in enhanced and bactericidal activity for DAP against HOU503 at 168 h. Our data provide further support for the use of combinations of DAP with AMP, ERT, CPT, and RIF in infections caused by biofilm producing VREfm. Further research involving DAP combinations against biofilm-producing enterococci is warranted.

Assessment of Tedizolid In Vitro Activity and Resistance Mechanisms against a Collection of Enterococcus spp. Causing Invasive Infections, Including Isolates Requiring an Optimized Dosing Strategy for Daptomycin from U.S. and European Medical Centers, 2016 to 2018

High-level aminoglycoside resistance was noted in 30.0% of Enterococcus faecalis and 25.2% of Enterococcus faecium isolates. Only 3.3% and 2.1% of E. faecalis isolates had elevated daptomycin MIC (≥2 mg/liter) and vancomycin resistance, respectively. In contrast, 37.4% to 40.3% of E. faecium isolates exhibited these phenotypes. Tedizolid inhibited 98.9% to 100.0% of enterococci causing serious invasive infections, including resistant subsets. Oxazolidinone resistance was mainly driven by G2576T; however, optrA and poxtA genes were also detected, including poxtA in the United States and Turkey.

Treatment and outcomes of Enterococcus faecium bloodstream infections in solid organ transplant recipients

Optimal antimicrobial therapy for Enterococcus faecium bloodstream infection (EFBSI) in the solid organ transplant (SOT) population is not well defined. The purpose of this study was to describe the pharmacotherapy and outcomes of EFBSI in SOT patients. This was a single-center retrospective cohort of SOT patients with EFBSI from 2013 to 2019. Susceptibility testing was performed with Vitek^® 2 or Etest. Estimates of optimal DAP pharmacokinetic/pharmacodynamic exposures (dose <10 mg/kg, fAUC/MIC >27.4) were made from previously established literature and equations. Fifty-one unique cases were included in the analysis. The median age was 61 years and liver (64%), intestinal (19%), and kidney (12%) were the most common organs transplanted. Most patients had indwelling central lines (75%) at the time of bacteremia; intra-abdominal abscesses/fluid collections were present in 44% of patients and 8% had endocarditis. Nineteen (37%) patients had polymicrobial infections. The most common definitive antimicrobial regimens were as follows: DAP plus beta-lactam (46%), DAP monotherapy (18%), and LZD (25%). Of the 33 patients that received DAP, 21% of E faecium isolates developed DAP resistance. 30-day mortality was 25% overall but higher in patients who received an initial DAP dose <10 mg/kg (43% vs 13%). Vancomycin-resistance, severity of illness, neutropenia, and source control were also associated with mortality. Inadequate DAP dosing for EFBSI may be associated with mortality in the SOT population. Larger, controlled analyses are necessary to determine the impact of optimized pharmacodynamics in this population.

One Size Fits All? Application of Susceptible-Dose-Dependent Breakpoints to Pediatric Patients and Laboratory Reporting

The Clinical and Laboratory Standards Institute antimicrobial and antifungal standards define a susceptible-dose-dependent (SDD) category for certain organisms and drug combinations. Reporting MICs within the SDD category suggests that treatment success is likely with increased drug exposure. These breakpoints are based on pharmacokinetic, pharmacodynamic, and clinical outcome data from adults and not pediatric patients. This commentary aims to discuss the implications of reporting SDD interpretations for pediatric patients and recommends laboratory reporting comments.

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 (fAUC_0–24/MIC) > 27.4 and fAUC_0–24/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.

Linezolid vs glycopeptides in the treatment of glycopeptide-susceptible Enterococcus faecium bacteraemia: A propensity score matched comparative study

BACKGROUND

The incidence of ampicillin-resistant Enterococcus faecium bacteraemia is increasing. Vancomycin remains the first-line treatment in areas with a high prevalence of glycopeptide-susceptible isolates, but data comparing its clinical outcomes with other treatments are lacking. The objective of this study was to compare the effectiveness and safety of linezolid and glycopeptides for the treatment of glycopeptide-susceptible E. faecium bloodstream infection (GSEF-BSI).

METHODS

This retrospective observational cohort study was conducted from January 2006 to May 2018 at the Hospital del Mar, Barcelona, Spain, and compared the clinical outcomes and safety of linezolid and glycopeptides in adult patients with GSEF-BSI. The main outcomes included clinical cure at the end of therapy, 30-day mortality, microbiological eradication and attributable length of stay (LOS). Propensity score matching was performed to reduce potential confounders among groups.

RESULTS

In total, 105 patients with GSEF-BSI were included (linezolid, n=38; glycopeptides, n=67). After propensity score matched analysis, 56 (53.3%) patients, 28 in each cohort, entered the final analysis. No differences were observed in any of the main clinical outcomes among patients treated with linezolid or glycopeptides: clinical cure [16/28 (57.1%) vs 13/28 (46.4%), P=0.593], 30-day mortality [8/28 (28.6%) vs 12/28 (42.9%), P=0.403], microbiological eradication [22/28 (78.6%) vs 20/28 (71.4%), P=0.758] and median attributable LOS (18.0 vs 17.0 days, P=0.924). Adverse events were similar in both groups.

CONCLUSIONS

Linezolid and glycopeptides showed similar clinical effectiveness and safety in the treatment of GSEF-BSI. Linezolid could be an alternative to glycopeptides in the treatment of GSEF-BSI.

Pharmacodynamics of daptomycin in combination with other antibiotics for the treatment of enterococcal bacteraemia

Daptomycin is commonly prescribed in combination with other antibiotics for treatment of enterococcal bacteraemia. Whilst a free drug area under the concentration-time curve to minimum inhibitory concentration (fAUC/MIC) ratio >27.4 is associated with 30-day survival with daptomycin monotherapy, it is unknown whether receipt of other antibiotics affects this threshold. Data were pooled from seven published trials assessing outcomes in daptomycin-treated enterococcal bacteraemia, including patients receiving daptomycin (≥72 h) and any β-lactam, intravenous aminoglycoside, linezolid, tigecycline and/or vancomycin. Exposures were calculated using a published population pharmacokinetic model based on creatinine clearance, 90% protein binding and daptomycin Etest MIC. The fAUC/MIC threshold predictive of 30-day survival was determined by classification and regression tree analysis. Following pooling of data, 240 adults were included; 137 (57.1%) were alive at 30 days. A majority of patients were immunosuppressed (65.8%) and received a β-lactam (94.6%). Examining the threshold in low-acuity patients (n = 135) to control for co-morbidities, these patients were more likely to survive when fAUC/MIC >12.3 was achieved (63.2% vs. 20.0%; P = 0.015). The difference remained significant in a multivariable logistic regression model that controlled for infection source and immunosuppression (P = 0.017). This threshold is 2-fold lower than that observed with daptomycin monotherapy. Probabilities of threshold attainment using a 10 mg/kg/day dose were 100% for isolates with MICs ≤ 2 mg/L and 95.2% for a 12 mg/kg/day dose for MICs of 4 mg/L. These data support the use of high-dose daptomycin in combination with another antibiotic for treatment of enterococcal bacteraemia.

The New, New Daptomycin Breakpoint for Enterococcus spp

In 2019, the Clinical and Laboratory Standards Institute revised the daptomycin breakpoints for Enterococcus spp. twice in rapid succession. Analyses leading to these revisions included review of testing issues, murine and human in vivo pharmacodynamics, safety of off-label doses, and treatment outcomes. The data review brought up a dilemma that is encountered with increasing frequency: a breakpoint supported by pharmacokinetic/pharmacodynamic modeling that bisected the wild-type Enterococcus faecium MIC distribution. In such instances, not only does the probability of pharmacokinetic/pharmacodynamic targets need to be taken into account but also the probability that the laboratory can generate an accurate MIC that is reproducible within one interpretive category.

Novel Strategies for the Management of Vancomycin-Resistant Enterococcal Infections

PURPOSE OF REVIEW

Vancomycin-resistant enterococci (VRE) are important nosocomial pathogens that commonly affect critically ill patients. VRE have a remarkable genetic plasticity allowing them to acquire genes associated with antimicrobial resistance. Therefore, the treatment of deep-seated infections due to VRE has become a challenge for the clinician. The purpose of this review is to assess the current and future strategies for the management of recalcitrant deep-seated VRE infections and efforts for infection control in the hospital setting.

RECENT FINDINGS

Preventing colonization and decolonization of multidrug-resistant bacteria are becoming the most promising novel strategies to control and eradicate VRE from the hospital environment. Fecal microbiota transplantation (FMT) has shown remarkable results on treating colonization and infection due to Clostridiodes difficille and VRE, as well as to recover the integrity of the gut microbiota under antibiotic pressure. Initial reports have shown the efficacy of FMT on reestablishing patient microbiota diversity in the gut and reducing the dominance of VRE in the gastrointestinal tract. In addition, the use of bacteriophages may be a promising strategy in eradicating VRE from the gut of patients. Until these strategies become widely available in the hospital setting, the implementation of infection control measures and stewardship programs are paramount for the control of this pathogen and each program should provide recommendations for the proper use of antibiotics and develop strategies that help to detect populations at risk of VRE colonization, prevent and control nosocomial transmission of VRE, and develop educational programs for all healthcare workers addressing the epidemiology of VRE and the potential impact of these pathogens on the cost and outcomes of patients. In terms of antibiotic strategies, daptomycin has become the standard of care for the management of deep-seated infections due to VRE. However, recent evidence indicates that the efficacy of this antibiotic is limited, and higher (10-12 mg/kg) doses and/or combination with β-lactams is needed for therapeutic success. Clinical data to support the best use of daptomycin against VRE are urgently needed. This review provides an overview of recent developments regarding the prevention, treatment, control, and eradication of VRE in the hospital setting. We aim to provide an update of the most recent therapeutic strategies to treat deep-seated infections due to VRE.