Should High-dose Daptomycin be an Alternative Treatment Regimen for Enterococcal Endocarditis?

Treatment of Enterococcus faecalis Infective Endocarditis: A Continuing Challenge

Today, Enterococcus faecalis is one of the main causes of infective endocarditis in the world, generally affecting an elderly and fragile population, with a high mortality rate. Enterococci are partially resistant to many commonly used antimicrobial agents such as penicillin and ampicillin, as well as high-level resistance to most cephalosporins and sometimes carbapenems, because of low-affinity penicillin-binding proteins, that lead to an unacceptable number of therapeutic failures with monotherapy. For many years, the synergistic combination of penicillins and aminoglycosides has been the cornerstone of treatment, but the emergence of strains with high resistance to aminoglycosides led to the search for new alternatives, like dual beta-lactam therapy. The development of multi-drug resistant strains of Enterococcus faecium is a matter of considerable concern due to its probable spread to E. faecalis and have necessitated the search of new guidelines with the combination of daptomycin, fosfomycin or tigecycline. Some of them have scarce clinical experience and others are still under investigation and will be analyzed in this review. In addition, the need for prolonged treatment (6–8 weeks) to avoid relapses has forced to the consideration of other viable options as outpatient parenteral strategies, long-acting administrations with the new lipoglycopeptides (dalbavancin or oritavancin), and sequential oral treatments, which will also be discussed.

Enterococcus faecalis endocarditis: what's next?

Enterococcus faecalis infective endocarditis (EFIE) is a complex entity in rapid evolution. Although largely relevant findings from recent studies have advanced the knowledge on EFIE and led to some changes in clinical guidelines, there are still a number of gaps to be filled. Coordinated, international, multicenter efforts are needed to obtain quality data that rend the health systems and scientific community prepared enough to understand and handle this infection. In this Perspective, some of the most relevant aspects concerning the epidemiology, clinical presentation and outcomes, diagnostic approaches and antibiotic therapy of EFIE are addressed. Also, several potential future clinical developments in the field are discussed.

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.

Efficacy of Daptomycin-Containing Regimen for Treatment of Staphylococcal or Enterococcal Vertebral Osteomyelitis: A Prospective Clinical Experience

Vertebral osteomyelitis (VO) is a compelling clinical entity for clinicians, because of its insidious and indolent course that makes diagnosis difficult. A concern is reported about the choice of antibiotic regimens, duration of therapy, and criteria to switch to oral therapy. We conducted a prospective observational study. All consecutive hospitalized patients with a confirmed diagnosis of VO caused by staphylococcal or enterococcal strains were analyzed. The primary endpoint was the analysis of clinical cure at the end of therapy. A propensity score for receiving therapy with daptomycin was added to the model. During the study period, 60 episodes of confirmed VO were observed. The main etiology of infection was methicillin-resistant Staphylococcus aureus (29%). Overall, clinical failure at end of therapy was reported in 11 (18.3%) patients. Logistic regression analysis, after propensity score, showed that >2 vertebrae involved (OR 2.4, CI95% 1.12–5.24, p = 0.002) and inadequate drainage of infection (OR 4.8, CI95% 2.45–8.51, p < 0.001) were independently associated with failure of therapy, while the use of a daptomycin-containing-regimen (OR 0.15, CI 95% 0.04–0.46, p < 0.001) with clinical cure. VO caused by staphylococcal or enterococcal strains is associated with an important rate of clinical failure. Daptomycin-containing regimen was strongly associated with clinical cure. Considering that over 70% of VO etiology is caused by Gram-positive strains but the etiology of infection is obtained in about 75% of cases, these data may help physicians to choose the appropriate antibiotic regimen.

Enterococcus faecalis Endocarditis and Outpatient Treatment: A Systematic Review of Current Alternatives

The selection of the best alternative for Enterococcus faecalis infective endocarditis (IE) continuation treatment in the outpatient setting is still challenging. Three databases were searched, reporting antibiotic therapies against E. faecalis IE in or suitable for the outpatient setting. Articles the results of which were identified by species and treatment regimen were included. The quality of the studies was assessed accordingly with the study design. Data were extracted and synthesized narratively. In total, 18 studies were included. The treatment regimens reported were classified regarding the main antibiotic used as regimen, based on Aminoglycosides, dual β-lactam, teicoplanin, daptomycin or dalbavancin or oral therapy. The regimens based on aminoglycosides and dual β-lactam combinations are the treatment alternatives which gather more evidence regarding their efficacy. Dual β-lactam is the preferred option for high level aminoglycoside resistance strains, and for to its reduced nephrotoxicity, while its adaptation to the outpatient setting has been poorly documented. Less evidence supports the remaining alternatives, but many of them have been successfully adapted to outpatient care. Teicoplanin and dalbavancin as well as oral therapy seem promising. Our work provides an extensive examination of the potential alternatives to E. faecalis IE useful for outpatient care. However, the insufficient evidence hampers the attempt to give a general recommendation.

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.