Prolonged Use of Oritavancin for Vancomycin-Resistant Enterococcus faecium Prosthetic Valve Endocarditis

Managing Antimicrobial Resistance in the Emergency Department

(Basic awareness and understanding of antimicrobial resistance and prevailing mechanisms can aid emergency physicians in providing appropriate care to patients with infections due to a multidrug-resistant organism (MDRO). Empiric treatment of MDRO infections should be approached with caution and guided by the most likely pathogens based on differential diagnosis, severity of the illness, suspected source of infection, patient-specific factors, and local antibiotic susceptibility patterns. Newer broad-spectrum antibiotics should be reserved for critically ill patients where there is a high likelihood of infection with an MDRO.).

New advances in management and treatment of cardiac implantable electronic devices infections

Cardiac implantable electronic devices (CIED) are increasingly used worldwide, and infection of these devices remains one of the most feared complications.CIED infections (CDIs) represent a challenge for physicians and the healthcare system in general as they require prolonged hospitalization and antibiotic treatment and are burdened by high mortality and high costs, so management of CDIs must be multidisciplinary.The exact incidence of CDIs is difficult to define, considering that it is influenced by various factors mainly represented by the implanted device and the type of procedure. Risk factors for CDIs could be divided into three categories: device related, patient related, and procedural related and the etiology is mainly sustained by Gram-positive bacteria; however, other etiologies cannot be underestimated. As a matter of fact, the two cornerstones in the treatment of these infections are device removal and antimicrobial treatment. Finally, therapeutic drug monitoring and PK/PD correlations should be encouraged in all patients with CDIs receiving antibiotic therapy and may result in a better clinical outcome and a reduction in antibiotic resistance and economic costs.In this narrative review, we look at what is new in the management of these difficult-to-treat infections.

Vancomycin-resistant enterococcus bloodstream infection successfully managed with oritavancin and fosfomycin as sequential treatment

Bloodstream infections caused by vancomycin-resistant enterococci are increasingly reported and a consensus therapy does not exist. Oritavancin has shown good antimicrobial activity against VRE, but its use is mainly limited to skin, soft tissue, and/or bone infections. Fosfomycin is increasingly used for enterococcal infections (including bloodstream infections and endocarditis) as a partner drug given its anti-biofilm and synergistic properties. Recently in vitro and in vivo synergism between oritavancin and fosfomycin against VRE isolates has been demonstrated. Herein we report the case of a hematologic patient with a VRE bloodstream infection successfully treated with oritavancin and fosfomycin as sequential treatment.

New Antimicrobials and New Therapy Strategies for Endocarditis: Weapons That Should Be Defended

The overall low-quality evidence concerning the clinical benefits of different antibiotic regimens for the treatment of infective endocarditis (IE), which has made it difficult to strongly support or reject any regimen of antibiotic therapy, has led to a discrepancy between the available guidelines and clinical practice. In this complex scenario, very recently published guidelines have attempted to fill this gap. Indeed, in recent years several antimicrobials have entered the market, including ceftobiprole, ceftaroline, and the long-acting lipoglycopeptides dalbavancin and oritavancin. Despite being approved for different indications, real-world data on their use for the treatment of IE, alone or in combination, has accumulated over time. Furthermore, an old antibiotic, fosfomycin, has gained renewed interest for the treatment of complicated infections such as IE. In this narrative review, we focused on new antimicrobials and therapeutic strategies that we believe may provide important contributions to the advancement of Gram-positive IE treatment, providing a summary of the current in vitro, in vivo, and clinical evidence supporting their use in clinical practice.

The Clinical Efficacy of Multidose Oritavancin: A Systematic Review

Oritavancin (ORI) is a semisynthetic lipoglycopeptide approved as a single 1200 mg dose intravenous infusion for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) caused by Gram-positive organisms in adults. The pharmacokinetic/pharmacodynamic (PK/PD) linear kinetic profile and long terminal half-life (~393 h) of ORI make it therapeutically attractive for the treatment of other Gram-positive infections for which prolonged therapy is needed. Multidose regimens are adopted in real-world clinical practice with promising results, but aggregated efficacy data are still lacking. A comprehensive search on PubMed/Medline, Scopus, Cochrane and Google Scholar databases was performed to include papers published up to the end of January 2023. All articles on ORI multiple doses usage, including case reports, with quantitative data and relevant clinical information were included. Two reviewers independently assessed papers against the inclusion/exclusion criteria and for methodological quality. Differences in opinion were adjudicated by a third party. From 1751 potentially relevant papers identified by this search, a total of 16 studies met the inclusion criteria and were processed further in the final data analysis. We extracted data concerning clinical response, bacteriologic response, mortality and adverse events (AEs). From the 16 included papers, 301 cases of treatment with multidose ORIs were identified. Multidose regimens comprised an initial ORI dose of 1200 mg followed by 1200 mg or 800 mg subsequent doses with a varying total number and frequency of reinfusions. The most often treated infections and isolates were osteomyelitis (148; 54.4%), ABSSSI (35; 12.9%) and cellulitis (14; 5.1%); and MRSA (121), MSSA (66), CoNS (17), E. faecalis (13) and E. faecium (12), respectively. Clinical cure and improvement by multidose ORI regimens were observed in 85% (231/272) and 8% (22/272) patients, respectively. Multidose ORI was safe and well tolerated; the most frequent AEs were infusion-related reactions and hypoglycemia. A multidose ORI regimen may be beneficial in treating other Gram-positive infections besides ABSSSIs, with a good safety profile. Further studies are warranted to ascertain the superiority of one multidose ORI scheme or posology over the other.

#AMRrounds: a systematic educational approach for navigating bench to bedside antimicrobial resistance

Antimicrobial resistance (AMR) continues to serve as a major global health crisis. Clinicians practising in this modern era are faced with ongoing challenges in the therapeutic management of patients suffering from antimicrobial-resistant infections. A strong educational understanding and synergistic application of clinical microbiology, infectious disease and pharmacological concepts can assist the adventuring clinician in the navigation of such cases. Important items include mobilizing laboratory testing for pathogen identification and susceptibility data, harnessing an understanding of intrinsic pathogen resistance, acknowledging epidemiological resistance trends, recognizing acquired AMR mechanisms, and consolidating these considerations when constructing an ideal pharmacological plan. In this article, we outline a novel framework by which to systematically approach clinical AMR, encourage AMR-related education and optimize therapeutic decision-making in AMR-related illnesses.

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.

Heartbreaking Decisions: The Dogma and Uncertainties of Antimicrobial Therapy in Infective Endocarditis

Infective endocarditis (IE) is a rare but increasingly prevalent disease with high morbidity and mortality, requiring antimicrobials and at times surgical intervention. Through the decades of healthcare professionals' experience with managing IE, certain dogmas and uncertainties have arisen around its pharmacotherapy. The introduction of new antimicrobials and novel combinations are exciting developments but also further complicate IE treatment choices. In this review, we provide and evaluate the relevant evidence focused around contemporary debates in IE treatment pharmacotherapy, including beta-lactam choice in MSSA IE, combination therapies (aminoglycosides, ceftaroline), the use of oral antimicrobials, the role of rifamycins, and long-acting lipoglycopeptides.

Role of Oritavancin in the Treatment of Infective Endocarditis, Catheter- or Device-Related Infections, Bloodstream Infections, and Bone and Prosthetic Joint Infections in Humans: Narrative Review and Possible Developments

Oritavancin is a long-acting lipoglycopeptide with in vitro activity against Gram-positive pathogens, as well as good bactericidal activity and sterilisation ability in biofilm. It has been approved for acute bacterial skin and skin structure infections (ABSSSI), but recent reports have demonstrated possible off-label uses, such as for vancomycin resistant enterococci (VRE), deep-seated infections including those involving prosthetic material and invasive infections. The aim of this work is to review the uses of oritavancin outside of ABSSSI, focusing on its real-life applications on infective endocarditis, catheter- or device-related infections, bloodstream infections, and bone and prosthetic joint infections in humans, as well as possible future applications. We performed a narrative review, collecting the literature published between 1 December 2002 and 1 November 2022 on PubMed and the Cochrane Library using the term 'oritavancin'. Available studies have shown how effective it is in different settings, suggesting an opportunity for step-down strategies or outpatient management of infections requiring a long duration of antibiotic treatment. So far, evidence is still scarce, and limited to a few studies and case reports, mostly focusing on Staphylococcus aureus as the major isolate. Concerns about fluid intake for dilution and interaction with coagulation markers also need to be taken into account. Further studies are required in order to assess the safety and effectiveness of Oritavancin in vascular, prosthetic, or device-related infections, as well as in resistant Gram-positive bacteria or enterococcal infections.

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.

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.

Dalbavancin as sequential therapy for infective endocarditis due to Gram-positive organisms: a review

Dalbavancin is a parenteral lipoglycopeptide antibiotic derived from teicoplanin, an analogue of vancomycin. It is mainly used for skin and soft tissue infections. The sustained half-life of approximately 14 days makes dalbavancin a novel option for potential use as sequential treatment in infections such as infective endocarditis, which require prolonged antibiotic courses. However, only a few studies have been reported in the literature, and the use of dalbavancin remains limited. This article is a review of the currently available literature using dalbavancin for the treatment of infective endocarditis due to Gram-positive organisms. Almost all patients received dalbavancin as sequential therapy following standard-of-care antibiotics. The overall clinical efficacy of dalbavancin was approximately 90%, and it appeared to be well tolerated.

Kimyrsa and Orbactiv - A Tale of Two Formulations

Kimyrsa is a new formulation (NF) of the original formulation of oritavancin ([OF] Orbactiv). Comparatively, the obvious benefit with this product is the shortened infusion time and flexibility with solution compatibility, but otherwise maintains a similar pharmacokinetic and microbiologic profile. At present, the NF lacks significant real-world experience relative to other available lipoglycopeptides and thus its place in therapy remains difficult to predict but would not be expected to be significantly different than its OF.

New Perspectives on Antimicrobial Agents: Long-Acting Lipoglycopeptides

The long-acting lipoglycopeptides (LGPs) dalbavancin and oritavancin are semisynthetic antimicrobials with broad and potent activity against Gram-positive bacterial pathogens. While they are approved by the Food and Drug Administration for acute bacterial skin and soft tissue infections, their pharmacological properties suggest a potential role of these agents for the treatment of deep-seated and severe infections, such as bloodstream and bone and joint infections. The use of these antimicrobials is particularly appealing when prolonged therapy, early discharge, and avoidance of long-term intravascular catheter access are desirable or when multidrug-resistant bacteria are suspected. This review describes the current evidence for the use of oritavancin and dalbavancin in the treatment of invasive infections, as well as the hurdles that are preventing their optimal use. Moreover, this review discusses the current knowledge gaps that need to be filled to understand the potential role of LGPs in highly needed clinical scenarios and the ongoing clinical studies that aim to address these voids in the upcoming years.

Efficacy and safety of novel glycopeptides versus vancomycin for the treatment of gram-positive bacterial infections including methicillin resistant Staphylococcus aureus: A systematic review and meta-analysis

OBJECTIVE

To compare between current evidence of novel glycopeptides against vancomycin for the treatment of gram-positive bacterial infections.

METHODOLOGY

A systematic review and meta-analysis was done. Major databases were searched for eligible randomized control trials that assessed clinical success, microbiological success and safety profile of novel glycopeptides versus vancomycin for infections caused by gram-positive bacteria.

RESULTS

This meta-analysis included eleven trials (7289 participants) comparing telavancin, dalbavancin and oritavancin with vancomycin. No differences were detected between novel glycopeptides and vancomycin for the treatment of skin and soft tissue infections (SSTIs) among modified intent-to-treat patients (OR: 1.04, CI: 0.92-1.17) as well as within the clinically evaluable patients (OR: 1.09, CI: 0.91-1.30). Data analysed from SSTIs, HAP and bacteremia studies on telavancin showed insignificant high clinical response in microbiologically evaluable patients infected with methicillin resistant Staphylococcus aureus (MRSA) (OR: 1.57, CI: 0.94-2.62, p: 0.08) and in the eradication of MRSA (OR: 1.39, CI: 0.99-1.96, P:0.06). Dalbavancin was non-inferior to vancomycin for the treatment of osteomyelitis in a phase II trial, while it was superior to vancomycin for the treatment of bacteremia in a phase II trial. Data analysed from all trials showed similar rates of all-cause mortality between compared antibiotics groups (OR: 0.67, CI: 0.11-4.03). Telavancin was significantly related with higher adverse events (OR: 1.24, CI: 1.07-1.44, P: <0.01) while dalbavancin and oritavancin were associated with significant fewer adverse events (OR: 0.73, CI: 0.57-0.94, p: 0.01; OR: 0.72, CI: 0.59-0.89, p: <0.01 respectively).

CONCLUSION

Efficacy and safety profiles of both dalbavancin and oritavancin were the same as vancomycin in the treatment of gram-positive bacterial infections in different clinical settings, while telavancin might be an effective alternative to vancomycin in MRSA infections, but caution is required during its clinical use due to the high risk of adverse events, especially nephrotoxicity.

Role of membrane proteins in bacterial resistance to antimicrobial peptides

Several natural antimicrobial peptides (AMPs), including the novel semisynthetic lipoglycopeptide antibiotics telavancin, dalbavancin, and oritavancin, have been approved for clinical use to address the growing problem of multiple antibiotic-resistant Gram-positive bacterial infections. Nevertheless, the efficacy of these antibiotics has already been compromised. The SARS-CoV-2 pandemic led to the increased clinical use of all antibiotics, further promoting the development of bacterial resistance. Therefore, it is critical to gain a deeper understanding of the role of resistance mechanisms to minimize the consequential risks of long-term antibiotic use and misuse. Here, we summarize for the first time the current knowledge of resistance mechanisms that have been shown to cause resistance to clinically used AMPs, with particular focus on membrane proteins that have been reported to interfere with the activity of AMPs by affecting the binding of AMPs to bacteria.

Role or oritavancin and dalbavancin in acute bacterial skin and skin structure infections and other potential indications

PURPOSE OF REVIEW

To discuss the currently available evidence about the use oritavancin and dalbavancin for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and for other potential indications.

RECENT FINDINGS

In this review, we briefly summarize the available data on efficacy (from randomized controlled trials) and on effectiveness and cure rates (from observational studies) pertaining to the use of oritavancin and dalbavancin either for ABSSSI or for other indications.

SUMMARY

Oritavancin and dalbavancin are valid options for outpatient therapy and early discharge in patients with ABSSSI, especially when adherence to oral therapy cannot be guaranteed or no oral choices are available. Furthermore, it is worth noting that a non-negligible portion (sometimes the majority) of oritavancin and dalbavancin use in available real-life experiences is for indications other than ABSSSI, especially for Gram-positive osteomyelitis and endocarditis. The number of studies on the use of long-acting lipoglycopeptides for these currently off-label indications is rapidly increasing and will help to further optimize the use of these peculiar antibiotics in the forthcoming future.

Antibiotic Approvals in the Last Decade: Are We Keeping Up With Resistance?

OBJECTIVE

To review the spectrum of activity, efficacy, safety, and role in therapy of all antibiotics and related biologics approved by the Food and Drug Administration (FDA) in the last decade.

DATA SOURCES

A literature search was performed using PubMed and Google Scholar (2010 to end May 2021) with the search terms' name of the antibiotic or the biologic. Data were also obtained from the prescribing information, FDA, and ClinicalTrials.gov websites.

STUDY SELECTION

All relevant English-language, late phase clinical trials assessing the safety and efficacy of the identified drugs were included. Review articles and references of retrieved articles were evaluated for relevant data.

DATA SYNTHESIS

Antibiotic resistance is a public health crisis, and antibiotic development is imperative to outpace the ability of bacteria to develop resistance. Only 17 new systemic antibiotics and 1 related biologic have been approved by the FDA since 2010. Among these drugs, 14 were approved for common bacterial infections, 1 was approved for Clostridioides difficile infection (CDI), 1 was licensed to prevent CDI recurrence, and 2 were approved for drug-resistant tuberculosis. Very few antibiotics are in clinical development.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

The arrival of these new antibiotics was welcomed with great enthusiasm, particularly when they met previously unmet medical needs. Unfortunately, the majority of them represent modifications to existing chemical structures rather than new drug classes. Despite the availability of these antibiotics, managing patients with deep-seated infections and those with extensively resistant gram-negative organisms remains challenging.

CONCLUSIONS

The number of new antibiotics and their indications are not keeping up with resistance and the needs of the patients.

The Increasing Issue of Vancomycin-Resistant Enterococci and the Bacteriocin Solution

Enterococci are commensals of human and other animals’ gastrointestinal tracts. Only making up a small part of the microbiota, they have not played a significant role in research, until the 1980s. Although the exact year is variable according to different geographical areas, this was the decade when vancomycin-resistant enterococci (VRE) were discovered and since then their role as causative agents of human infections has increased. Enterococcus faecium is on the WHO’s list of “bacteria for which new antibiotics are urgently needed,” and with no new antibiotics in development, the situation is desperate. In this review, different aspects of VRE are outlined, including the mortality caused by VRE, antibiotic resistance profiles, animal-modeling efforts, and virulence. In addition, the limitations of current antibiotic treatments for VRE and prospective new treatments, such as bacteriocins, are reviewed.

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.

New-Generation Antibiotics for Treatment of Gram-Positive Infections: A Review with Focus on Endocarditis and Osteomyelitis

Infective endocarditis, osteomyelitis, and osteosynthesis-associated infections are mostly caused by Gram-positive bacteria. They are often difficult to treat and are associated with a poor prognosis. In the past 20 years, nine antibiotic drugs with predominant activity against Gram-positive bacteria have been introduced and approved by the Food and Drug Administration or the European Medicines Agency: ceftaroline, daptomycin, telavancin, dalbavancin, oritavancin, linezolid, tedizolid, delafloxacin, and omadacycline. This narrative review aims to provide an overview on these antibiotics with a special focus on their use in infective endocarditis, osteomyelitis, and osteosynthesis-associated infections. Although some of these approved antibiotics are promising, they should not be used as first- or second-line therapy, awaiting more clinical data.

Continued Dosing of Oritavancin for Complicated Gram-Positive Infections

Several retrospective and cohort analyses have suggested that continued dosing of oritavancin is both safe and efficacious for complicated Gram-positive infections, such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci.

In vitro activity of oritavancin alone or in combination against vancomycin-susceptible and -resistant enterococci

OBJECTIVES

The optimal treatment for serious infections due to Enterococcus spp. is unknown although combination antimicrobial therapy is often recommended for invasive infections to achieve bactericidal activity and improve clinical outcomes. Oritavancin is a novel lipoglycopeptide agent with in vitro activity against enterococci, including vancomycin-resistant VanA-type Enterococcus faecium. Data on its activity in combination with other antibacterials are limited. The objective of this study was to evaluate the activity of oritavancin alone and in combination with ceftriaxone, daptomycin, gentamicin, linezolid and rifampicin against vancomycin-susceptible and -resistant enterococci in in vitro time-kill analyses.

METHODS

Five enterococcal strains were used for all experiments: three vancomycin-resistant VanA-type E. faecium clinical bloodstream isolates, vancomycin-resistant VanA-type E. faecium ATCC 700221 and vancomycin-susceptible Enterococcus faecalis ATCC 29212. Individual drugs were tested at ¼, ½, 1, 2 and 4× MIC. Oritavancin combination experiments were performed with each agent at ¼× MIC.

RESULTS

Daptomycin was the most active single agent and was bactericidal against all strains at 4× MIC, followed by oritavancin, which was bactericidal against all three clinical VRE strains at ≥2× MIC. In combination experiments at ¼× MIC, oritavancin was synergistic with gentamicin against strains not displaying high-level aminoglycoside resistance. No other synergy against VRE strains was observed in any experiment. Strain- and drug-dependent antagonism was observed for many combinations.

CONCLUSIONS

These in vitro data do not support the routine use of combination therapy with oritavancin in the treatment of infections due to VRE.

Out of Sight but Not Out of Mind: Caring for Patients Receiving OPAT During the SARS-CoV-2 Pandemic

In an effort to “flatten the curve” of SARS-CoV-2, society is urged to practice social distancing. However, the management of other disease states may require some patients to undergo outpatient parenteral antimicrobial therapy (OPAT). Practical considerations for OPAT management during an infectious pandemic are reviewed. These include shortening durations of therapy, utilizing the oral route, avoiding medications requiring therapeutic drug monitoring, selecting antimicrobials with long durations, decreasing frequency of laboratory blood draws, and performing tele-health visits.

Treatment of osteoarticular, cardiovascular, intravascular-catheter-related and other complicated infections with dalbavancin and oritavancin: A systematic review

BACKGROUND

There is increasing interest in the use of oritavancin and dalbavancin for complicated Gram-positive infections as an alternative to in-hospital intravenous or outpatient antimicrobial therapy.

OBJECTIVE

To evaluate the efficacy and safety of long-acting lipoglycopeptides (laLGPs) in patients with osteoarticular, cardiovascular, intravascular-catheter-related and other complicated infections.

METHODS

A systematic literature search was performed using 'dalbavancin' and 'oritavancin' as search terms. For inclusion in this review, studies had to include at least one human subject treated for an indication other than acute bacterial skin and skin structure infections. The primary outcome for this review was clinical success as defined by each individual study, and patients were stratified by type of infection.

RESULTS

In total, 38 studies (18 randomized controlled trials/case series and 20 case reports) met the inclusion criteria. The most common off-label indication for oritavancin and dalbavancin was osteoarticular infection, with a median success rate of 73% [interquartile range (IQR) 58-85%] among the 14 studies with more than one patient. The success rate for endocarditis and cardiac-device-related infections was 68% (IQR 56-86%) among nine studies, and the success rate for catheter-related bloodstream infection was 75% (IQR 59-90%) among seven studies. Among the 16 studies of almost 700 patients receiving laLGPs, there were 98 reports of adverse events, resulting in 13% of treated patients reporting an event.

CONCLUSIONS

This review provides evidence that laLGPs are safe and efficacious for osteoarticular, cardiovascular, intravascular-catheter-related and other complicated infections. Further research is needed to confirm these results.

Clinical Outcomes and Economic Impact of Oritavancin for Gram-Positive Infections: A Single Academic Medical Center Health System Experience

BACKGROUND

Vancomycin treatment of complicated Gram-positive infections is associated with laboratory monitoring, nephrotoxicity, and multiple daily dosing. Oritavancin, a lipoglycopeptide antibiotic with a once-weekly dosing strategy and similar but slightly broader spectrum of activity, presents several opportunities over vancomycin to improve compliance and convenience for the patient. Minimal real-world clinical and acquisition cost data in the inpatient setting and clinical data surrounding multiple dosing in the outpatient setting have limited oritavancin use despite its potential logistic advantages.

OBJECTIVES

We describe inpatient and outpatient oritavancin administration, clinical outcomes, and economic impact.

METHODS

This was a single-center, retrospective case series of patients treated with at least one dose of oritavancin between May 2015 and September 2017 at an academic medical center in the USA. A simplified cost-avoidance analysis was conducted assuming the patient had a national health insurance plan and focused on hospital days prevented.

RESULTS

Seventy-five patients received oritavancin during the study period. The most common use of oritavancin was in patients with acute bacterial skin and skin structure infections (ABSSSI), defined as cellulitis, abscess or non-surgical wounds (n = 25, 33%), followed by surgical wound infections (n = 12, 16%) and osteomyelitis or septic arthritis (n = 10, 13%). Clinical cure or improvement was achieved in 68 patients (93.2%), while five patients (6.8%) failed treatment; adverse reactions were reported in nine patients (12%). Thirty-five patients received oritavancin as inpatients; 20 patients (57%) had at least one hospital day avoided due to inpatient oritavancin administration resulting in a total cost avoidance of US$343,654.

CONCLUSION

In this series of 75 patients with Gram-positive infections, oritavancin treatment resulted in clinical cure or improvement in most patients, and was generally well tolerated. Inpatient administration may avoid costs and outpatient administration is a reasonable consideration for patients in which prolonged antibiotic therapy is necessary.

Advantages of Outpatient Treatment with Long-Acting Lipoglycopeptides for Serious Gram-Positive Infections: A Review

Treatment of serious gram-positive infections presents multiple challenges. Treatment often results in prolonged hospitalization for administration of intravenous antimicrobials and presents an inefficient use of hospital resources. Prolonged hospitalization is typically also unfavorable to patient preferences and potentially subjects patients to additional health care-associated complications. Current strategies of transition to outpatient settings-outpatient parenteral antimicrobial therapy and use of oral antibiotics-often do not adequately serve vulnerable populations for whom there is often no alternative to inpatient therapy. Specifically, people who use drugs, those who cannot reliably adhere to unsupervised treatment (poor mental or physical health), people with complicating life circumstances (e.g., homelessness, incarceration, rural location), and those with inadequate health insurance remain hospitalized for weeks longer than persons without such conditions. We suspected that long-acting lipoglycopeptides (laLGP), such as dalbavancin and oritavancin, may be useful in patient transitions to outpatient settings. Thus, we conducted a search of the peer-reviewed literature using the PubMed, Google Scholar, and MEDLINE databases. Based on accumulating literature, it appears that laLGPs offer a reliable alternative therapeutic strategy that addresses many of the personal and systemic barriers to the traditional transitioning approaches. Current evidence also suggests that these agents may be cost-effective from patient, payer, and hospital perspectives. Barriers to broader use of laLGPs include, among others, a relative lack of prospective data regarding efficacy in serious infections, a narrow United States Food and Drug Administration-approved indication restricted to only acute bacterial skin and skin structure infections, and lack of reimbursement infrastructure for inpatient settings.

The CHROME Study, a Real-world Experience of Single- and Multiple-Dose Oritavancin for Treatment of Gram-Positive Infections

Background

Oritavancin (ORI) is a long-acting lipoglycopeptide indicated for the treatment of adult patients with acute bacterial skin and skin structure infections (ABSSSIs) caused or suspected to be caused by susceptible Gram-positive (GP) pathogens.

Methods

Data collected from a retrospective observational program (2014–2017), Clinical and Historic Registry and Orbactiv Medical Evaluation (CHROME), describe the utilization, outcomes, and adverse events (AEs) associated with ORI in 440 patients treated at 26 US sites for ABSSSI and other GP infections.

Results

Clinical success in evaluable patients receiving at least 1 dose of oritavancin was 88.1% (386/438). In a subgroup of patients who received ORI for skin and soft tissue infections (n = 401) and bacteremia (n = 7), clinical success was achieved in 89.0% and 100%, respectively. A cohort of 32 patients received 2–10 ORI doses separated by no more than 14 days for complicated GP infections. Clinical success was observed in 30 of 32 patients (93.8%), including 10 of 11 (90.9%) patients with bone and joint infections and 7 of 8 (87.5%) patients with osteomyelitis. In the safety evaluable population, the overall rate of AEs was 6.6%.

Conclusions

We describe results from a real-world program that includes the largest multicenter, retrospective, observational study in patients who received at least 1 dose of ORI for the treatment of GP infections. This study confirms that ORI is an effective, well-tolerated antibiotic used in single and multiple doses for the treatment of ABSSSIs and complicated GP infections.

Treatment of Multidrug-Resistant Vancomycin-Resistant Enterococcus faecium Hardware-Associated Vertebral Osteomyelitis with Oritavancin plus Ampicillin

Weekly oritavancin plus ampicillin continuous infusion combination therapy was used to successfully treat a deep spine vancomycin-resistant Enterococcus faecium infection associated with hardware. Checkerboard and time-kill assays confirmed synergy between these two antibiotics. Further synergies of oritavancin and ampicillin with rifampin or the endogenous human antimicrobial peptide cathelicidin LL-37 were demonstrated.

Methicillin-Resistant Staphylococcus aureus Prosthetic Valve Endocarditis: Pathophysiology, Epidemiology, Clinical Presentation, Diagnosis, and Management

Staphylococcus aureus prosthetic valve endocarditis (PVE) remains among the most morbid bacterial infections, with mortality estimates ranging from 40% to 80%. The proportion of PVE cases due to methicillin-resistant Staphylococcus aureus (MRSA) has grown in recent decades, to account for more than 15% of cases of S. aureus PVE and 6% of all cases of PVE. Because no large studies or clinical trials for PVE have been published, most guidelines on the diagnosis and management of MRSA PVE rely upon expert opinion and data from animal models or related conditions (e.g., coagulase-negative Staphylococcus infection). We performed a review of the literature on MRSA PVE to summarize data on pathogenic mechanisms and updates in epidemiology and therapeutic management and to inform diagnostic strategies and priority areas where additional clinical and laboratory data will be particularly useful to guide therapy. Major updates discussed in this review include novel diagnostics, indications for surgical management, the utility of aminoglycosides in medical therapy, and a review of newer antistaphylococcal agents used for the management of MRSA PVE.

Combatting resistant enterococcal infections: a pharmacotherapy review

INTRODUCTION

The role of enterococci in infectious diseases has evolved from a gut and urinary commensal to a major pathogen of concern. Few options exist for resistant enterococci, and appropriate use of the available agents is crucial.

AREAS COVERED

Herein, the authors discuss antibiotics with clinically useful activity against Enterococcus faecalis and E. faecium. The article specifically discusses: antibiotics active against enterococci and their mechanism of resistance, pharmacokinetic and pharmacodynamic principles, in vitro combinations, and clinical studies which focus on urinary tract, intra-abdominal, central nervous system, and bloodstream infections due to enterococci.

EXPERT OPINION

Aminopenicillins are preferred over all other agents when enterococci are susceptible and patients can tolerate them. Daptomycin and linezolid have demonstrated clinical efficacy against vancomycin-resistant enterococci (VRE). Synergistic combinations are often warranted in complex infections of high inoculum and biofilms while monotherapies are generally appropriate for uncomplicated infections. Although active against resistant enterococci, the pharmacokinetics, efficacy and safety of tigecycline and quinupristin/dalfopristin can problematical for severe infections. For cystitis, amoxicillin, nitrofurantoin, or fosfomycin are ideal. Recently, approved agents such as tedizolid and oritavancin have good in vitro activity against VRE but clinical studies against other resistant enterococci are lacking.

Developments in Glycopeptide Antibiotics

Glycopeptide antibiotics (GPAs) are a key weapon in the fight against drug resistant bacteria, with vancomycin still a mainstream therapy against serious Gram-positive infections more than 50 years after it was first introduced. New, more potent semisynthetic derivatives that have entered the clinic, such as dalbavancin and oritavancin, have superior pharmacokinetic and target engagement profiles that enable successful treatment of vancomycin-resistant infections. In the face of resistance development, with multidrug resistant (MDR) S. pneumoniae and methicillin-resistant Staphylococcus aureus (MRSA) together causing 20-fold more infections than all MDR Gram-negative infections combined, further improvements are desirable to ensure the Gram-positive armamentarium is adequately maintained for future generations. A range of modified glycopeptides has been generated in the past decade via total syntheses, semisynthetic modifications of natural products, or biological engineering. Several of these have undergone extensive characterization with demonstrated in vivo efficacy, good PK/PD profiles, and no reported preclinical toxicity; some may be suitable for formal preclinical development. The natural product monobactam, cephalosporin, and β-lactam antibiotics all spawned multiple generations of commercially and clinically successful semisynthetic derivatives. Similarly, next-generation glycopeptides are now technically well positioned to advance to the clinic, if sufficient funding and market support returns to antibiotic development.

Mechanisms of antimicrobial resistance among hospital-associated pathogens

INTRODUCTION

The introduction of antibiotics revolutionized medicine in the 20th-century permitting the treatment of once incurable infections. Widespread use of antibiotics, however, has led to the development of resistant organisms, particularly in the healthcare setting. Today, the clinician is often faced with pathogens carrying a cadre of resistance determinants that severely limit therapeutic options. The genetic plasticity of microbes allows them to adapt to stressors via genetic mutations, acquisition or sharing of genetic material and modulation of genetic expression leading to resistance to virtually any antimicrobial used in clinical practice. Areas covered: This is a comprehensive review that outlines major mechanisms of resistance in the most common hospital-associated pathogens including bacteria and fungi. Expert commentary: Understanding the genetic and biochemical mechanisms of such antimicrobial adaptation is crucial to tackling the rapid spread of resistance, can expose unconventional therapeutic targets to combat multidrug resistant pathogens and lead to more accurate prediction of antimicrobial susceptibility using rapid molecular diagnostics. Clinicians making treatment decisions based on the molecular basis of resistance may design therapeutic strategies that include de-escalation of broad spectrum antimicrobial usage, more focused therapies or combination therapies. These strategies are likely to improve patient outcomes and decrease the risk of resistance in hospital settings.

A Real-world Patient Registry for Oritavancin Demonstrates Efficacy and Safety Consistent With the Phase 3 SOLO Program

Background

Oritavancin is a lipoglycopeptide used in the treatment of acute bacterial skin and skin structure infections (ABSSSIs) in adults. To characterize its use in patients in the postapproval setting, a patient registry was developed.

Methods

Data collected in an ongoing retrospective observational registry are used to evaluate the utilization, outcomes, and adverse events (AEs) associated with oritavancin for the treatment of infections presumed or confirmed to be caused by gram-positive (GP) bacteria in clinical practice.

Results

Data for 112 patients from 8 sites were collected. All patients received a single 1200-mg dose of oritavancin mostly in an infusion center. Infection type included cellulitis (67.0%), cutaneous abscess (21.4%), and wound (4.5%). Most patients (72.3%) received 1 or more antimicrobial agents for the index GP infection within 28 days prior to oritavancin treatment. Of positive cultures obtained prior to oritavancin administration, methicillin-resistant Staphylococcus aureus was the predominant pathogen (78.4%). A positive clinical response was observed in 92.8% of patients, and microbial eradication was observed in 90.0% of patients with post-therapy cultures. Within 28 days following oritavancin administration, 4 (3.6%) patients were hospitalized for failure of treatment of the index infection. Five (4.5%) patients experienced 1 or more possible drug-related AEs, which were consistent with types previously reported. There were no drug-related serious AEs reported.

Conclusions

Clinical and microbiologic outcomes and safety of single-dose oritavancin 1200 mg were similar in this older patient population with multiple comorbid conditions to those observed in the phase 3 SOLO trials.

Advances in prevention and treatment of vancomycin-resistant Enterococcus infection

PURPOSE OF REVIEW

This article reviews data, particularly from the last 2 years, addressing the prevention and treatment of vancomycin-resistant Enterococcus (VRE). We focus on infection control, particularly active screening, use of contact precautions as well as pharmacologic options for therapy. This is timely given the evolving priorities in efforts towards the prevention and treatment of multidrug-resistant organisms globally.

RECENT FINDINGS

Key findings include new data regarding the impact of contact precautions on the incidence of VRE colonization and bloodstream infection, new laboratory screening methods, and novel decolonization strategies and treatments.

SUMMARY

Additional and specific measures beyond standard precautions for infection prevention of VRE remain controversial. Horizontal measures such as chlorhexidine bathing appear beneficial, as are nontouch environmental cleaning methods. Treatment options for invasive disease have improved considerably in the last decade. Decolonization strategies require further research. Overall, the threat of VRE seems exaggerated.

Future trends in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection: An in-depth review of newer antibiotics active against an enduring pathogen

Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a major public health problem. Vancomycin and teicoplanin have been in clinical use for several decades but their drawbacks are well described. In the last 10 years, several antibiotics have been made available for clinical use. Daptomycin and linezolid have been extensively used during this period. Other agents such as ceftaroline, ceftobiprole, dalbavancin, oritavancin, tedizolid and telavancin have been approved by regulatory agencies since 2009. Many others, such as the newer tetracyclines, fluoroquinolones, oxazolidinones and pleuromutilins, are in various stages of development. In addition, an ongoing multicentre trial is investigating the role of combination of vancomycin or daptomycin with β-lactam antibiotics. This review discusses the role of the newer antibiotics, reflecting the views of the 6th MRSA Consensus Conference meeting of the International Society of Chemotherapy MRSA Working Group that took place in 2016.

Real-World Experience with Oritavancin Therapy in Invasive Gram-Positive Infections

Introduction

Oritavancin is a novel lipoglycopeptide approved for acute bacterial skin and skin structure infections. The pharmacokinetic profile and convenient one-time dosing make oritavancin an enticing option for other serious Gram-positive infections requiring prolonged treatment courses. Unfortunately, data for using oritavancin in these populations are limited.

Methods

We report ten cases of oritavancin use for invasive Gram-positive infections in our health system, and provide a review of the currently available literature regarding oritavancin therapy for invasive infections.

Results

Among the ten patients who received oritavancin, the most common infection was methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia (n = 5, 50%). Other indications for oritavancin use included methicillin-resistant S. aureus (MRSA) bursitis (n = 1, 10%), group B streptococcal bacteremia with native tricuspid valve infective endocarditis (n = 1, 10%), coagulase-negative staphylococcal bacteremia (n = 1, 10%), MSSA deep tissue infection (n = 1, 10%), and enterococcal bacteremia (n = 1, 10%). Oritavancin was well tolerated, and 7/10 (70%) patients were successfully treated.

Conclusion

Oritavancin is a potential option for patients with invasive Gram-positive infections. Further study is warranted.

Oritavancin: a long-acting antibacterial lipoglycopeptide

Oritavancin is a new lipoglycopeptide antibacterial agent with an exceptionally long terminal half-life and a rapid bactericidal effect. Multiple mechanisms of action lead to a broad activity against Gram-positive bacteria, such as staphylococci, streptococci and enterococci, including methicillin-resistant Staphylococcus aureus. Its long terminal half-life allows for single-dose treatment of acute bacterial skin and skin structure infections. Oritavancin was found to be safe and effective in treating acute bacterial skin and skin structure infections in adults and it is currently approved in the USA and in Europe for this indication. Unfortunately, data for other indications are lacking. Here, we review chemistry, microbiology, pharmacology, efficacy and tolerability of oritavancin.