Time to abandon ampicillin plus gentamicin in favour of ampicillin plus ceftriaxone in Enterococcus faecalis infective endocarditis? A meta-analysis of comparative trials

Comparison of ceftriaxone versus ceftaroline in combination with ampicillin or penicillin against Enterococcus faecalis

Enterococcus faecalis infective endocarditis treatment with ampicillin plus ceftriaxone has not changed the mortality rates by over 30%. We identified borderline-penicillin-resistant, ampicillin-susceptible E. faecalis (borderline-PRASEF; penicillin MIC 4-8 µg/mL, breakpoint ≤8 µg/mL) isolates that have decreased ampicillin-ceftriaxone activity, which is present in 25% of isolates in New York City. Alternatively, ceftaroline is more active against E. faecalis than ceftriaxone. We compared the activity of ampicillin or penicillin plus ceftriaxone or ceftaroline against nine borderline-PRASEF and seven penicillin-susceptible (penicillin MIC ≤2 µg/mL) E. faecalis isolates via 24 h time-kill assays. MICs were obtained via broth microdilution per CLSI. Ampicillin, penicillin, and ceftaroline were tested at subinhibitory concentrations (0.25 × MIC and 0.5 × MIC) and ceftriaxone at the free plasma steady-state concentration (17.2 µg/mL). All experiments were completed in duplicate with a starting inoculum of 106 CFU/mL. After 24 h, antimicrobial activity was measured as ≥2-log10 CFU/mL decrease from the initial inoculum. Combinations were assessed for synergy (≥2-log10 CFU/mL decrease from the most active single agent). Ceftriaxone and ceftaroline MICs were more likely to be higher in borderline-PRASEF isolates compared to penicillin-susceptible isolates. Ceftaroline-based combinations more often demonstrated synergy and activity than ceftriaxone combinations. When assessed by penicillin MIC, ceftriaxone-based combinations less frequently demonstrated synergy and activity against borderline-PRASEF isolates compared to ceftaroline-based combinations. Ceftaroline-based combinations may be an effective alternative targeting E. faecalis, including borderline-PRASEF.IMPORTANCEThe preferred therapy for treatment of Enterococcus faecalis infective endocarditis is ampicillin plus ceftriaxone; however, there is a need for alternative treatments given the unchanged mortality rates exceeding 30%. Recent data show decreased ampicillin-ceftriaxone activity against borderline-penicillin-resistant, ampicillin-susceptible E. faecalis (borderline-PRASEF), which is present in 25% of isolates. Ceftaroline is an alternative cephalosporin that has been explored as it does not carry the risks ceftriaxone has to increase vancomycin resistance and Clostridoides difficile infection. Ceftaroline also provides saturation of both essential penicillin-binding protein (PBP) 4 and non-essential PBP2/3, whereas ceftriaxone only binds to PBP2/3. The activity of ceftaroline-based combinations against borderline-PRASEF is unknown. This study demonstrates the ability of ampicillin or penicillin plus ceftaroline to maintain activity against borderline-PRASEF where ampicillin or penicillin plus ceftriaxone combination activity is limited.

Treatment of Complicated Gram-Positive Bacteremia and Infective Endocarditis

The Gram-positive cocci Staphylococcus aureus, Streptococcus spp., and Enterococcus spp. are the most frequent causative organisms of bloodstream infections and infective endocarditis. "Complicated bacteremia" is a term used in S. aureus bloodstream infections and originally implied the presence of metastatic infectious foci (i.e. complications of S. aureus bacteremia). These complications demand longer antimicrobial treatment durations and, frequently, interventional source control. Several risk factors for the incidence of bacteremia complications have been identified and are often used for the definition of complicated bacteremia. Here, we discuss management and diagnostic approaches and treatment options for patients with complicated bacteremia, with particular focus on infective endocarditis. We also summarize the available evidence regarding imaging modalities and the choice of antimicrobial mono- or combination therapy according to resistance patterns for these pathogens as well as treatment durations and optimized application routes. Finally, we synopsize current and future areas of research in complicated bacteremia and infective endocarditis.

Evaluation of ampicillin plus ceftobiprole combination therapy in treating Enterococcus faecalis infective endocarditis and bloodstream infection

Enterococcus faecalis is responsible for numerous serious infections, and treatment options often include ampicillin combined with an aminoglycoside or dual beta-lactam therapy with ampicillin and a third-generation cephalosporin. The mechanism of dual beta-lactam therapy relies on the saturation of penicillin-binding proteins (PBPs). Ceftobiprole exhibits high affinity binding to nearly all E. faecalis PBPs, thus suggesting its potential utility in the treatment of severe E. faecalis infections. The availability of therapeutic drug monitoring (TDM) for ampicillin and ceftobiprole has prompted the use of this drug combination in our hospital. Due to the time-dependent antimicrobial properties of these antibiotics, an infusion administration longer than indicated was chosen. From January to December 2020, twenty-one patients were admitted to our hospital for severe E. faecalis infections and were treated with this approach. We retrospectively analyzed their clinical characteristics and pharmacological data. Most patients achieved an aggressive PK/PD target (T > 4-8 minimum inhibitory concentration, MIC) when this alternative drug combination regimen was used. Our analysis included the study of E. faecalis biofilm production, as well as the kinetics of bacterial killing of ceftobiprole alone or in combination with ampicillin. Time-kill experiments revealed strong bactericidal activity of ceftobiprole alone at concentrations four times higher than the MIC for some enterococcal strains. In cases where a bactericidal effect of ceftobiprole alone was not evident, synergism with ampicillin and bactericidal activity were demonstrated instead. The prolonged infusion of ceftobiprole, either alone or with ampicillin, emerges as a valuable option for the treatment of severe invasive E. faecalis infections.

Outcomes of Enterococcus faecalis infective endocarditis according to MIC of amoxicillin: a multicentric study

Background

The incidence of Enterococcus faecalis infective endocarditis is increasing over time. Data on the impact of minimum inhibitory concentration (MIC) of amoxicillin on treatment outcomes are scarce. The objective of this study was to describe the epidemiology of E. faecalis infective endocarditis and to evaluate whether the MIC of amoxicillin might influence mortality.

Materials

We retrospectively included all consecutive patients diagnosed with definite E. faecalis infective endocarditis between 2013 and 2020 in 11 French hospitals. We extracted data from the local diagnosis-related group (DRG) database and matched these data with microbiological results. Amoxicillin MIC was determined by Etest strip. The primary endpoints were endocarditis-related mortality and risk factors for endocarditis-related mortality including amoxicillin MIC.

Results

A total of 403 patients with definite E. faecalis infective endocarditis were included. Patients were predominantly male (76.4%) with a median age of 74 years (67-82). Embolic complications occurred in 170 (42.1%) patients. Cardiac surgery was performed in 158 (61.5%) patients. The endocarditis-related mortality rate was 28.3% and the median delay between mortality and onset of hospitalization was 24 (9; 41) days. E. faecalis MIC of amoxicillin was available for 246 (61%) patients. The median MIC was 0.5 mg/L (0.4-0.7). Amoxicillin MIC was not found to be associated with in-hospital mortality. None of the variables included in the multivariate model were identified as a risk factor for mortality and there was no correlation between mortality and the duration of treatment for 4 weeks versus 6 weeks.

Conclusions

Higher amoxicillin MIC was not a risk factor leading to endocarditis-related mortality in definite E. faecalis infective endocarditis. However, further studies are needed to assess the effect of amoxicillin MIC on relapse.

Revisiting the Evidence Base That Informs the Use of Adjunctive Therapy for Enterococcus faecalis Endocarditis: A Systematic Review and Meta-Analysis

BACKGROUND

Guidelines recommend adjunctive gentamicin for the treatment of Enterococcus faecalis infective endocarditis (EFIE) despite a risk of toxicity. We sought to revisit the evidence for adjunctive therapy in EFIE and to synthesize the comparative safety and effectiveness of aminoglycosides versus ceftriaxone by systematic review and meta-analysis.

METHODS

For historical context, we reviewed seminal case series and in vitro studies on the evolution from penicillin monotherapy to modern-day regimens for EFIE. Next, we searched MEDLINE and Embase from inception to 16 January 2024 for studies of EFIE that compared adjunctive aminoglycosides versus ceftriaxone or adjunctive versus monotherapy. Where possible, clinical outcomes were compared between regimens using random effects meta-analysis. Otherwise, data were narratively summarized.

RESULTS

The meta-analysis was limited to 10 observational studies at high risk of bias (911 patients). Relative to adjunctive ceftriaxone, gentamicin had similar all-cause mortality (risk difference [RD], -0.8%; 95% confidence interval [CI], -5.0 to 3.5), relapse (RD, -0.1%; 95% CI, -2.4 to 2.3), and treatment failure (RD, 1.1%; 95% CI, -1.6 to 3.7) but higher discontinuation due to toxicity (RD, 26.3%; 95% CI, 19.8 to 32.7). The 3 studies that compared adjunctive therapy to monotherapy included only 30 monotherapy patients, and heterogeneity precluded meta-analysis.

CONCLUSIONS

Adjunctive ceftriaxone appeared to be equally effective and less toxic than gentamicin for the treatment of EFIE. The existing evidence does not clearly establish the superiority of either adjunctive therapy or monotherapy. Pending randomized evidence, if adjunctive therapy is to be used, ceftriaxone appears to be a reasonable option.

Update on the epidemiology, diagnosis, and management of infective endocarditis: A review

Despite advancements in the diagnosis and treatment of infective endocarditis (IE), the burden of IE has remained relatively high over the past decade. With an ageing population and an increasing proportion of healthcare-associated IE, the epidemiology of IE has undergone significant changes. Staphylococcus aureus has evolved as the most common causative microorganism, even in most low- and middle-income countries. Several imaging modalities and novel microbiological tests have emerged to facilitate the diagnosis of IE. Outpatient parenteral antibiotic treatment and oral step-down antibiotic treatment have become new trends for the management of IE. Early surgical intervention, particularly within seven days, should be considered in cases of IE with appropriate surgical indications. We comprehensively review the updated epidemiology, microbiology, diagnosis, and management of IE.

Enterococcal endocarditis management and relapses

Introduction

Enterococcus faecalis is the third micro-organism causing endocarditis and is associated with a significant relapse rate. The objective of this study was to describe the management of patients with Enterococcus faecalis endocarditis (EE) and its implication for relapses.

Methods

We conducted a monocentric, retrospective analysis of all patients hospitalized for EE including endocarditis or infection of cardiac implantable electronic device defined by the modified ESC 2015 Duke criteria in a referral centre in Paris, France.

Results

Between October 2016, and September 2022, 54 patients with EE were included, mostly men (n = 40, 74%) with a median age of 75 [68-80] years. A high risk for infective endocarditis (IE) was found in 42 patients (78%), including 14 (26%) previous histories of IE, and 32 (59%) histories of valvular cardiac surgery. The aortic valve was the most frequently affected (n = 36, 67%). Combination therapy was mainly amoxicillin-ceftriaxone during all the curative antibiotic therapy duration (n = 31, 57%). Surgery was indicated for 40 patients (74%), but only 27 (50%) were operated on, mainly due to their frailty. Among the 17 deaths (32%), six (11%) happened during the first hospitalization for EE. A suppressive antibiotic treatment was initiated in 15 (29%) patients, mostly because of not performing surgery. During the 6-year study period an EE relapse occurred in three (6%) patients.

Conclusions

EE is a worrying disease associated with a high risk of relapse and significant mortality. Suppressive antibiotic therapy could be a key treatment to limit the occurrence of relapses.

Guidelines for Diagnosis and Management of Infective Endocarditis in Adults: A WikiGuidelines Group Consensus Statement

Importance

Practice guidelines often provide recommendations in which the strength of the recommendation is dissociated from the quality of the evidence.

Objective

To create a clinical guideline for the diagnosis and management of adult bacterial infective endocarditis (IE) that addresses the gap between the evidence and recommendation strength.

Evidence Review

This consensus statement and systematic review applied an approach previously established by the WikiGuidelines Group to construct collaborative clinical guidelines. In April 2022 a call to new and existing members was released electronically (social media and email) for the next WikiGuidelines topic, and subsequently, topics and questions related to the diagnosis and management of adult bacterial IE were crowdsourced and prioritized by vote. For each topic, PubMed literature searches were conducted including all years and languages. Evidence was reported according to the WikiGuidelines charter: clear recommendations were established only when reproducible, prospective, controlled studies provided hypothesis-confirming evidence. In the absence of such data, clinical reviews were crafted discussing the risks and benefits of different approaches.

Findings

A total of 51 members from 10 countries reviewed 587 articles and submitted information relevant to 4 sections: establishing the diagnosis of IE (9 questions); multidisciplinary IE teams (1 question); prophylaxis (2 questions); and treatment (5 questions). Of 17 unique questions, a clear recommendation could only be provided for 1 question: 3 randomized clinical trials have established that oral transitional therapy is at least as effective as intravenous (IV)-only therapy for the treatment of IE. Clinical reviews were generated for the remaining questions.

Conclusions and Relevance

In this consensus statement that applied the WikiGuideline method for clinical guideline development, oral transitional therapy was at least as effective as IV-only therapy for the treatment of IE. Several randomized clinical trials are underway to inform other areas of practice, and further research is needed.

Infective Endocarditis in the Elderly: Challenges and Strategies

The specific management of infective endocarditis (IE) in elderly patients is not specifically addressed in recent guidelines despite its increasing incidence and high mortality in this population. The term "elderly" corresponds to different ages in the literature, but it is defined by considerable comorbidity and heterogeneity. Cancer incidence, specifically colorectal cancer, is increased in older patients with IE and impacts its outcome. Diagnosis of IE in elderly patients is challenging due to the atypical presentation of the disease and the lower performance of imaging studies. Enterococcal etiology is more frequent than in younger patients. Antibiotic treatment should prioritize diminishing adverse effects and drug interactions while maintaining the best efficacy, as surgical treatment is less commonly performed in this population due to the high surgical risk. The global assessment of elderly patients with IE, with particular attention to frailty and geriatric profiles, should be performed by multidisciplinary teams to improve disease management in this population.