Surrogate analysis of vancomycin to predict susceptible categorization of dalbavancin

Substance use disorder-associated infections' treatment with dalbavancin enabling outpatient transition (SUDDEN OUT) - an investigator-initiated single-arm unblinded prospective cohort study

Background

Severe gram-positive infections are frequent in people who inject drugs, and successful completion of treatment presents unique challenges in this population.

Objectives

We aimed to evaluate the feasibility of a long-acting antibiotic, dalbavancin, as an alternative to standard-of-care antibiotics for severe infections due to vancomycin-susceptible pathogens requiring ⩾2 weeks of therapy.

Design

We designed an investigator-initiated single-arm unblinded prospective cohort study to evaluate the safety and efficacy of an early switch to dalbavancin in two doses administered 1 week apart.

Methods

We screened patients admitted with bloodstream infection, osteomyelitis, septic arthritis, infective endocarditis or deep abscesses, and comorbid substance use disorder (SUD) for eligibility. Consenting patients were switched to dalbavancin within 7 days from their index culture. They were monitored in the hospital for efficacy and safety of the treatment until the second dose of dalbavancin 7 days later and then discharged if stable. Study participants were evaluated with a decision support engine for a hypothetical appropriate level of care regarding their SUD after discharge. Their follow-up was planned for 12 months from the index culture, either in-person or via telehealth/telephone.

Results

The enrollment was terminated early due to significant loss-to-follow-up. In all, 11 patients were enrolled, 4 completed 12 months of follow-up, 2 completed 8 months of follow-up, and 1 was seen once after discharge. The remaining five patients were lost to follow-up immediately after discharge. All 11 patients continued to improve after switching to dalbavancin between the first and second doses. There were two per-protocol failures of treatment. Dalbavancin was well tolerated, though some adverse events were reported.

Conclusion

Dalbavancin may be a safe and effective alternative for an early switch in treating severe gram-positive infections.

Trial registration

The trial was registered as NCT04847921 with clinicaltrials.gov.

Clinical Effectiveness and Pharmacokinetics of Dalbavancin in Treatment-Experienced Patients with Skin, Osteoarticular, or Vascular Infections

Dalbavancin (DBV) is a lipoglycopeptide approved for the treatment of Gram-positive infections of the skin and skin-associated structures (ABSSSIs). Currently, its off-label use at different dosages for other infections deserves attention. This work aimed to study the clinical effectiveness and tolerability of DBV in outpatients with ABSSSIs, osteoarticular (OA), or other infections, treated with either one or two 1500 mg doses of dalbavancin, for different scheduled periods. A liquid chromatography–tandem mass spectrometry method was used to measure total DBV concentrations. PK/PD parameters and the clinical and microbiological features of this cohort were evaluated in order to investigate the best predictors of treatment success in real-life settings. Of the 76 screened patients, 41 completed the PK study. Long-term PK was comparable to previous studies and showed significant differences between genders and dosing schedules. Few adverse events were observed, and treatment success was achieved in the vast majority of patients. Failure was associated with lower PK parameters, particularly C_max. Concluding, we were able to describe DBV PK and predictors of treatment success in selected infections in this cohort, finding DBV C_max as a possible candidate for therapeutic drug-monitoring purposes, as well as highlighting the dual-dose one-week-apart treatment as the optimal choice for OA infections.

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.

Long-Term Pharmacokinetics of Dalbavancin in ABSSSI and Osteoarticular Settings: A Real-Life Outpatient Context

Dalbavancin is a lipoglycopeptide approved for treatment of Gram-positive infections of skin and skin-associated structures (ABSSSI). Currently, off-label use at high dosages for osteoarticular infections deserves attention. This work aimed to study the long-term plasma pharmacokinetics of dalbavancin in outpatients with ABSSSI or osteoarticular infections, treated either with one or two 1500 mg doses of dalbavancin. A liquid chromatography-tandem mass spectrometry method was used to measure total dalbavancin concentrations in plasma samples. The results were analyzed through a non-compartmental analysis (NCA). Breakpoint minimum inhibitory concentration (MIC) was used to calculate AUC/MIC and T > MIC parameters, adjusted by 93% protein binding. A total of 14 patients were enrolled, 11 with osteoarticular infection and 3 with ABSSSI. Long-term pharmacokinetics showed median T > MIC (0.125 mg/L) of 11.9 and 13.7 weeks for single and dual dose, respectively. Similarly, median AUC_0-2w/MIC ratios of 20,590 and 31,366 were observed for single and dual dose regimens, respectively. No adverse events were observed, and treatment success was achieved in 12/14 patients. Failure was associated with the worst clinical conditions, bone infections, and single dose. The results of this study show that dalbavancin exposure exceeds previously suggested pharmacodynamic targets. Optimization of these targets is needed for the osteoarticular setting.

Review: A Safety Profile of Dalbavancin for On- and Off-Label Utilization

Introduction

Dalbavancin is a bactericidal lipoglycopeptide active against gram-positives. Its use has been approved for the treatment of acute bacterial skin and skin structure infections (ABSSSI).

Methods

We conducted a narrative review of the literature on the safety profile of dalbavancin. The bibliographic research was carried out on the PubMed database on 6 November 2020 by seeking combinations of the following keywords: dalbavancin, adverse effects, safety, drug interactions, and skin infections.

Results

Five double-blind Phase 3 randomized clinical trials, 2 open-label randomized trials, and 4 retrospective studies were identified. No statistically significant differences were found between dalbavancin and comparators in the incidence of adverse events. Retrospective studies confirm the low incidence of adverse events.

Conclusion

Dalbavancin is a therapeutic option that has demonstrated an excellent safety profile, also in relation to the other MRSA therapies available. Its use represents a cost-effective solution for the treatment of those patients with ABSSSI who would need hospitalization. One limitation of this study is that most of the available data are from Phase III clinical trials. Further real-life studies with a larger sample size are therefore needed to better assess the safety profile of the dalbavancin, especially to investigate the true incidence of rare adverse events.

Current trends in the real-life use of dalbavancin: report of a study panel

Dalbavancin is a novel lipoglycopeptide antibiotic with a chemical structure similar to teicoplanin. Dalbavancin has been approved and marketed since 2014 in the USA and 2015 in the European Union for the treatment of acute bacterial skin and skin-structure infections (ABSSSIs) caused by Gram-positive cocci. ABSSSIs include infectious syndromes such as erysipelas, cellulitis, major cutaneous abscesses that require incision and drainage, and both surgical and traumatic wound infections. In current clinical practice, dalbavancin is also used for cardiac implantable electronic device-related soft tissue infection and other prosthetic infections, and therefore when the presence of biofilm is a concern. In this review, we aimed to highlight our experience with the use of dalbavancin for some of the most hard-to-treat Gram-positive infections, as well as a promising strategy in terms of pharmacoeconomic effectiveness. We describe our current real-life clinical practice with the use of dalbavancin, depicting a few representative clinical cases in order to share our own practice in the hospital setting.

Dalbavancin and telavancin in the treatment of infective endocarditis: a literature review

Glycopeptides have an established role in the management of infective endocarditis, and feature in current treatment guidelines. Newer lipoglycopeptide agents (dalbavancin, telavancin and oritavancin), which are analogues of glycopeptides with structural modifications giving rise to added novel mechanisms of antimicrobial activity, are approved for the treatment of Gram-positive skin and skin structure infections, and also for nosocomial pneumonia (only telavancin has approval for the latter indication). Recent evidence has also emerged to support their use in the treatment of bone and joint infections. This article reviews the current literature on dalbavancin and telavancin in the treatment of infective endocarditis, a condition for which the role of these agents is yet to be established.

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.

Serum Bactericidal Activity Levels Monitor to Guide Intravenous Dalbavancin Chronic Suppressive Therapy of Inoperable Staphylococcal Prosthetic Valve Endocarditis: A Case Report

Here we describe a case of a methicillin-resistant coagulase-negative staphylococci prosthetic valve endocarditis in a patient considered not eligible for valve replacement due to high perioperative mortality risk and who did not tolerate oral antibiotic treatment. Under these circumstances, intravenous long-term chronic suppressive antibiotic therapy with dalbavancin, scheduling the doses using the serum bactericidal activity titers, proved to be safe and effective.

Real-world experience with dalbavancin therapy in gram-positive skin and soft tissue infection, bone and joint infection

PURPOSE

Dalbavancin is a novel lipoglycopeptide with potent activity against several gram-positive pathogens, an excellent safety profile and a long elimination half-life.

METHODS

In this case series observed at the University Hospital of Vienna between 2015 and 2017, all adult patients with gram-positive infections who received at least one dosage of dalbavancin were screened (n = 118). A total of 72 patients were included in the final analysis. The number of included patients stratified by the source of infection was: skin and soft tissue infection (SSTI) (n = 26), osteomyelitis (n = 20), spondylodiscitis (n = 14), acute septic arthritis (n = 4) and prosthetic joint infection (n = 8).

RESULTS

In 46 patients (64%), clinical cure was detected at the end of dalbavancin therapy without additional antibiotic therapy. Of the 26 patients who received additional antibiotic therapy other than dalbavancin, 15 patients (21%) showed no clinical improvement under dalbavancin therapy, four patients (5%) had side effects (nausea n = 1, exanthema n = 2, hyperglycemia n = 1), and in seven patients (10%) clinical improvement under dalbavancin therapy was detected but antibiotic therapy was de-escalated to an oral drug.

CONCLUSION

We demonstrated high clinical effectiveness of dalbavancin for acute gram-positive infections primarily acute SSTI, acute septic arthritis, acute osteomyelitis and spondylodiscitis. In patients with biofilm-associated infection (chronic infection or joint prosthesis), source control was absolutely necessary for treatment success.

Emergence of a dalbavancin induced glycopeptide/lipoglycopeptide non-susceptible Staphylococcus aureus during treatment of a cardiac device-related endocarditis

In the present study, we demonstrated the emergence of dalbavancin non-susceptible and teicoplanin-resistant Staphylococcus aureus small colony variants which were selected in vivo through long-term treatment with dalbavancin. A 36-year-old man presented with a cardiac device-related S. aureus endocarditis and received long-term therapy with dalbavancin. Consecutively, two glycopeptide/lipoglycopeptide susceptible and two non-susceptible S. aureus isolates were obtained from blood cultures and the explanted pacemaker wire. The isolates were characterized by: standard typing methods, antimicrobial susceptibility testing, auxotrophic profiling, proliferation assays, scanning and transmission electron microscopy, as well as whole genome sequencing. The isolated SCVs demonstrated a vancomycin-susceptible but dalbavancin non-susceptible and teicoplanin-resistant phenotype whereof the respective MICs of the last isolate were 16- and 84-fold higher than the susceptible strains. All four strains were indistinguishable or at least closely related by standard typing methods (spa, MLST, and PFGE), and whole genome sequencing revealed only eight sequence variants. A consecutive increase in cell wall thickness (up to 2.1-fold), an impaired cell separation with incomplete or multiple cross walls and significantly reduced growth rates were observed in the present study. Therefore, the mutations in pbp2 and the DHH domain of GdpP were identified as the most probable candidates due to their implication in the biosynthesis and metabolism of the staphylococcal cell wall. For the first time, we demonstrated in vivo induced dalbavancin non-susceptible/teicoplanin resistant, but vancomycin and daptomycin susceptible S. aureus SCVs without lipopeptide or glycopeptide pretreatment, thus, indicating the emergence of a novel lipoglycopeptide resistance mechanism.

Emergence of dalbavancin non-susceptible, vancomycin-intermediate Staphylococcus aureus (VISA) after treatment of MRSA central line-associated bloodstream infection with a dalbavancin- and vancomycin-containing regimen

OBJECTIVES

Dalbavancin is a long-acting lipoglycopeptide with activity against gram-positives, including methicillin-resistant Staphylococcus aureus (MRSA). The potential for lipoglycopeptides, with half-lives greater than 1 week, to select for resistance is unknown. Here we explore a case of MRSA central line-associated bloodstream infection in which dalbavancin and vancomycin non-susceptibility emerged in a urine isolate collected after the patient was treated with vancomycin and dalbavancin sequentially.

METHODS

Isolates from blood and urine underwent susceptibility testing, and whole genome sequencing (WGS). The blood isolate was subjected to successive passage in vitro in the presence of escalating dalbavancin concentrations and the emergent isolate was subjected to repeat susceptibility testing and WGS.

RESULTS

The blood isolate was fully susceptible to vancomycin; however, MICs of the urine isolate to dalbavancin, vancomycin, telavancin, and daptomycin were at least fourfold higher than the blood-derived strain. Both strains were indistinguishable by spa and variable number tandem repeat (VNTR) typing, and WGS revealed only seven variants, indicating clonality. Four variants affected genes, including a 3bp in-frame deletion in yvqF, a gene which has been implicated in glycopeptide resistance. Vancomycin and dalbavancin non-susceptibility emerged in the blood isolate after successive passage in vitro in the presence of dalbavancin, and WGS identified a single non-synonymous variant in yvqF.

CONCLUSIONS

This is the first case in which VISA has emerged in the context of a dalbavancin-containing regimen. The selection for cross-resistance to vancomycin in vitro by dalbavancin exposure alone is troubling. Clinicians should be aware of the possibility for emergence of dalbavancin non-susceptibility and glycopeptide cross-resistance arising following therapy.

Single-Dose Dalbavancin: A Review in Acute Bacterial Skin and Skin Structure Infections

Intravenous dalbavancin (Dalvance^®, Xydalba^®), first approved as a two-dose regimen for the treatment of acute bacterial skin and skin structure infections (ABSSSI), has now been additionally approved as a single-dose regimen. This narrative review discusses the pharmacological properties of intravenous dalbavancin and its clinical efficacy and tolerability as a single-dose regimen in the treatment of adult patients with ABSSSI. Single-dose dalbavancin is an effective and generally well tolerated treatment option for adults with ABSSSI, with noninferior efficacy to the two-dose dalbavancin regimen with regard to early clinical response (at 48-72 h) and low rates of adverse events. Clinical success rates at days 14 and 28 also did not significantly differ between the single- and two-dose dalbavancin regimens; neither did clinical success rates at day 14 when analysed by baseline pathogen. It has a broad spectrum of activity against common ABSSSI-related pathogens, and a favourable pharmacokinetic profile allowing for the convenience of single-dose administration. Thus, dalbavancin presents a promising alternative to conventional antibacterials for the treatment of ABSSSI in adult patients.

Dalbavancin for the treatment of paediatric infectious diseases

To review the topics of interest related to the use of dalbavancin in paediatric patients. PubMed was used to search for all of the studies published over the last 15 years using the key word "dalbavancin". A total of 36 manuscripts were selected, and due to the limited pediatric experience a further research was performed in order to identify clinical trials ongoing. Three studies that concerned children were found in clinicaltrials.gov. This review considers also the manuscripts published on the adult population in order to highlight the gaps requiring further research at pediatric age. Dalbavancin has emerged as a promising agent against resistant Gram-positive invasive infections. It is approved in the United States and Europe for the treatment of adult patients with acute bacterial skin and skin structure infections (SSTIs). Compared to other available antibiotics that are active against multi-resistant bacteria, the advantages of dalbavancin include a lower potential for drug interactions and the possibility of fewer required doses due to a longer half-life. Pharmacokinetic characteristics of dalbavacin are attractive for its clinical impact, especially for children who may avoid prolonged hospitalization and central venous access. However, further studies are needed to establish its appropriate paediatric dosage before it can be licensed for use in newborns and children. For younger patients, at a time when infections due to multidrug-resistant Gram-positive pathogens are increasing, dosage, efficacy and safety data for dalbavancin are needed to ensure the highest antimicrobial efficacy while also minimizing the risk of adverse events.

New Approaches to Antibiotic Use and Review of Recently Approved Antimicrobial Agents

Antimicrobial drug-resistance continues to force adaptation in our clinical practice. We explore new evidence regarding adjunctive antibiotic therapy for skin and soft tissue abscesses as well as duration of therapy for intra-abdominal abscesses. As new evidence refines optimal practice, it is essential to support clinicians in adopting practice patterns concordant with evidence-based guidelines. We review a simple approach that can 'nudge' clinicians towards concordant practices. Finally, the use of novel antimicrobials will play an increasingly important role in contemporary therapy. We review five new antimicrobials recently FDA-approved for use in drug-resistant infections: dalbavancin, oritavancin, ceftaroline, ceftolozane-tazobactam, and ceftazidime-avibactam.

Dalbavancin Activity When Tested against Streptococcus pneumoniae Isolated in Medical Centers on Six Continents (2011 to 2014)

Dalbavancin, a novel lipoglycopeptide, was approved for use in 2014 by regulatory agencies in the United States and Europe for the treatment of skin and skin structure infections. The activity of dalbavancin was also widely assessed by determination of its activity against Streptococcus pneumoniae clinical isolates collected from patients on six continents monitored during two time intervals (2011 to 2013 and 2014). A total of 18,186 pneumococcal isolates were obtained from 49 nations and submitted to a monitoring laboratory as part of the SENTRY Antimicrobial Surveillance Program for reference susceptibility testing. The potency of dalbavancin against S. pneumoniae was consistent across the years that it was monitored, with the MIC50 and MIC90 being 0.015 and 0.03 μg/ml, respectively, and all isolates were inhibited by ≤0.12 μg/ml. The activity of dalbavancin was not adversely influenced by nonsusceptibility to β-lactams (ceftriaxone or penicillin), macrolides, clindamycin, fluoroquinolones, or tetracyclines or multidrug resistance (MDR). Regional variations in dalbavancin activity were not detected, but S. pneumoniae strains isolated in the Asia-Pacific region were more likely to be nonsusceptible to penicillin and ceftriaxone as well as to be MDR than strains isolated in North or South America and Europe. Direct comparisons of potency illustrated that dalbavancin (MIC50 and MIC90, 0.015 and 0.03 μg/ml, respectively) was 16-fold or more active than vancomycin (MIC50, 0.25 μg/ml), linezolid (MIC50, 1 μg/ml), levofloxacin (MIC50, 1 μg/ml), ceftriaxone (MIC90, 1 μg/ml), and penicillin (MIC90, 2 μg/ml). In conclusion, dalbavancin had potent and consistent activity against this contemporary (2011 to 2014) collection of S. pneumoniae isolates.

Emerging Resistance, New Antimicrobial Agents … but No Tests! The Challenge of Antimicrobial Susceptibility Testing in the Current US Regulatory Landscape

Accurate and timely performance of antimicrobial susceptibility testing (AST) by the clinical laboratory is paramount to combating antimicrobial resistance. The ability of laboratories in the United States to effectively perform ASTs is challenged by several factors. Some, such as new resistance mechanisms and the associated evolution of testing recommendations and breakpoints, are inevitable. Others are entirely man-made. These include unnecessarily strict US Food and Drug Administration (FDA) limitations on how commercial AST systems can be used for diagnostic testing, the absence of up-to-date performance data on these systems, and the lack of commercially available FDA-cleared tests for newer antimicrobial agents or for older agents with updated breakpoints. This viewpoint will highlight contemporary AST challenges faced by the clinical laboratory, and propose some solutions.

New Gram-Positive Agents: the Next Generation of Oxazolidinones and Lipoglycopeptides

The growing problem of antimicrobial resistance among bacterial pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), has reached a critical state. Tedizolid phosphate, dalbavancin, and oritavancin have recently been approved by the U.S. Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and represent the next generation of oxazolidinones and lipoglycopeptides. All three agents exhibit in vitro activity and clinical efficacy against MRSA. Tedizolid phosphate and oritavancin demonstrate in vitro activity against VRE. These new Gram-positive agents are reviewed here.

A Reference Broth Microdilution Method for Dalbavancin In Vitro Susceptibility Testing of Bacteria that Grow Aerobically

Antimicrobial susceptibility testing (AST) is performed to assess the in vitro activity of antimicrobial agents against various bacteria. The AST results, which are expressed as minimum inhibitory concentrations (MICs) are used in research for antimicrobial development and monitoring of resistance development and in the clinical setting for antimicrobial therapy guidance. Dalbavancin is a semi-synthetic lipoglycopeptide antimicrobial agent that was approved in May 2014 by the Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections caused by Gram-positive organisms. The advantage of dalbavancin over current anti-staphylococcal therapies is its long half-life, which allows for once-weekly dosing. Dalbavancin has activity against Staphylococcus aureus (including both methicillin-susceptible S. aureus [MSSA] and methicillin-resistant S. aureus [MRSA]), coagulase-negative staphylococci, Streptococcus pneumoniae, Streptococcus anginosus group, β-hemolytic streptococci and vancomycin susceptible enterococci. Similar to other recent lipoglycopeptide agents, optimization of CLSI and ISO broth susceptibility test methods includes the use of dimethyl sulfoxide (DMSO) as a solvent when preparing stock solutions and polysorbate 80 (P80) to alleviate adherence of the agent to plastic. Prior to the clinical studies and during the initial development of dalbavancin, susceptibility studies were not performed with the use of P-80 and MIC results tended to be 2-4 fold higher and similarly higher MIC results were obtained with the agar dilution susceptibility method. Dalbavancin was first included in CLSI broth microdilution methodology tables in 2005 and amended in 2006 to clarify use of DMSO and P-80. The broth microdilution (BMD) procedure shown here is specific to dalbavancin and is in accordance with the CLSI and ISO methods, with step-by-step detail and focus on the critical steps added for clarity.

Dalbavancin: A Novel Lipoglycopeptide Antibiotic with Extended Activity Against Gram-Positive Infections

Dalbavancin is a lipoglycopeptide antibiotic recently approved by the United States Food and Drug Administration (FDA) for acute bacterial skin and skin structure infections (ABSSSIs). It is active against gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), and minimum inhibitory concentrations (MICs) are consistently <0.125 µg/ml, much lower than most other anti-MRSA agents. Dalbavancin possesses an extended half-life of over 1 week, allowing an initial dose of 1000 mg followed by 500 mg 1 week later to complete a course of therapy for ABSSSI. It is approximately 95% protein bound and is widely distributed throughout the body, achieving concentrations similar to plasma levels in numerous tissues. Against MRSA, dalbavancin is 4–8 times more potent than vancomycin in vitro, and limited data suggest it possesses activity against MRSA with reduced susceptibility to vancomycin such as hVISA and VISA. Dalbavancin also possesses in vitro activity against streptococci and enterococci, although activity against vancomycin-resistant enterococci is lacking. In phase 3 ABSSSI studies, dalbavancin demonstrated similar activity to vancomycin and provides a more convenient dosing regimen. Limited phase 2 data suggest dalbavancin also possesses activity in catheter-related bloodstream infections. Potential further therapeutic uses include conditions that require long-term treatment such as osteomyelitis and infective endocarditis, although data are currently lacking. The extended half-life of dalbavancin, along with its in vitro activity against gram-positive organisms with reduced susceptibility to other anti-MRSA antibiotics, suggest it could have an exciting clinical role going forward.

Use of vancomycin as a surrogate for dalbavancin in vitro susceptibility testing: results from the DISCOVER studies

Background

Dalbavancin is a lipoglycopepetide antibiotic with activity against gram positive pathogens recently approved for treatment of acute bacterial skin and skin structure infections. Pending the introduction of antimicrobial susceptibility tests, we examined the utility of vancomycin inhibitory concentrations to predict dalbavancin susceptibility in a panel of isolates obtained from phase 3 registration studies.

Findings

99.6% of Staphylococcus aureus and 99.0% of beta-hemolytic streptococci which are susceptible to vancomycin will have an MIC at or below the US FDA susceptibility breakpoint for dalbavancin.

Conclusion

Vancomycin should be considered as a surrogate for in vitro dalbavancin susceptibility testing.