Worldwide assessment of dalbavancin activity and spectrum against over 6,000 clinical isolates

Unraveling novel mutation patterns and morphological variations in two dalbavancin-resistant MRSA strains in Austria using whole genome sequencing and transmission electron microscopy

BACKGROUND

The increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) strains resistant to non-beta-lactam antimicrobials poses a significant challenge in treating severe MRSA bloodstream infections. This study explores resistance development and mechanisms in MRSA isolates, especially after the first dalbavancin-resistant MRSA strain in our hospital in 2016.

METHODS

This study investigated 55 MRSA bloodstream isolates (02/2015-02/2021) from the University Hospital of the Medical University of Vienna, Austria. The MICs of dalbavancin, linezolid, and daptomycin were assessed. Two isolates (16-33 and 19-362) resistant to dalbavancin were analyzed via whole-genome sequencing, with morphology evaluated using transmission electron microscopy (TEM).

RESULTS

S.aureus BSI strain 19-362 had two novel missense mutations (p.I515M and p.A606D) in the pbp2 gene. Isolate 16-33 had a 534 bp deletion in the DHH domain of GdpP and a SNV in pbp2 (p.G146R). Both strains had mutations in the rpoB gene, but at different positions. TEM revealed significantly thicker cell walls in 16-33 (p < 0.05) compared to 19-362 and dalbavancin-susceptible strains. None of the MRSA isolates showed resistance to linezolid or daptomycin.

CONCLUSION

In light of increasing vancomycin resistance reports, continuous surveillance is essential to comprehend the molecular mechanisms of resistance in alternative MRSA treatment options. In this work, two novel missense mutations (p.I515M and p.A606D) in the pbp2 gene were newly identified as possible causes of dalbavancin resistance.

Simulated Target Attainment of Multidose Regimens of Dalbavancin for Prolonged Durations of Therapy

Background

Dalbavancin is a long-acting lipoglycopeptide antibiotic that is increasingly utilized for infections that require prolonged treatment durations despite the lack of Food and Drug Administration approval for these indications. There is no consensus regarding optimal dosing of dalbavancin for these infections and no available pharmacokinetic studies to identify optimal dosing for long-term use.

Methods

An in silico pharmacokinetic simulation was performed to assess the predicted dalbavancin concentration resulting from commonly utilized dosing regimens, in addition to modified regimens. The primary endpoint evaluated was days of median 24-hour free area under the curve over the minimum inhibitory concentration (AUC/MIC) >27.1, the established PK target.

Results

A dosing regimen of 1500 mg on day 0 and day 7 resulted in median AUC/breakpoint value above the target for 57 days (lower 95% confidence interval [CI], 37 days). A modified regimen of 1500 mg on day 0 and day 21 resulted in an additional 11 days of median AUC/breakpoint target attainment. The other standard dosing regimen modeled was 1000 mg on day 0, then 500 mg weekly for 5 doses. This regimen achieved the AUC/breakpoint target for 76 days (lower 95% CI, 59 days). This regimen was modified to 1000 mg on day 0, then 500 mg on days 14 and 28, which shortened the median effective treatment duration by 14 days but required 3 fewer doses.

Conclusions

These simulated results, when combined with the favorable observational data, support the use of commonly reported dalbavancin regimens for prolonged therapy durations. In addition, these pharmacokinetic/pharmacodynamic data support extending the dosing interval beyond the frequently reported weekly regimens, which should be investigated further with a clinical trial.

Staph wars: the antibiotic pipeline strikes back

Antibiotic chemotherapy is widely regarded as one of the most significant medical advancements in history. However, the continued misuse of antibiotics has contributed to the rapid rise of antimicrobial resistance (AMR) globally. Staphylococcus aureus, a major human pathogen, has become synonymous with multidrug resistance and is a leading antimicrobial-resistant pathogen causing significant morbidity and mortality worldwide. This review focuses on (1) the targets of current anti-staphylococcal antibiotics and the specific mechanisms that confirm resistance; (2) an in-depth analysis of recently licensed antibiotics approved for the treatment of S. aureus infections; and (3) an examination of the pre-clinical pipeline of anti-staphylococcal compounds. In addition, we examine the molecular mechanism of action of novel antimicrobials and derivatives of existing classes of antibiotics, collate data on the emergence of resistance to new compounds and provide an overview of key data from clinical trials evaluating anti-staphylococcal compounds. We present several successful cases in the development of alternative forms of existing antibiotics that have activity against multidrug-resistant S. aureus. Pre-clinical antimicrobials show promise, but more focus and funding are required to develop novel classes of compounds that can curtail the spread of and sustainably control antimicrobial-resistant S. aureus infections.

The effect of novel antimicrobial agents on the normal functioning of human intestinal microbiota: a systematic review

Antimicrobial agents have significant effects on the ecological balance of the human microbiota through incomplete absorption (e.g., orally administered antimicrobial agents) or secretion (e.g., by the salivary glands, in the bile, or from the intestinal mucosa) of the agents. This study aimed to examine the effects of novel antimicrobial agents on the normal functioning of the intestinal microbiota. The articles, written in English, were recovered from PubMed, ScienceDirect, Web of Science, Google Scholar, and DOAJ, as well as from manual searches using a reference list. “Microbiota”, “Intestinal Microbiota”, “Eubiotic Microbiota”, “Ecological Impact”, “Antimicrobial Agents,”, “Antibiotics”, “Dysbiosis”, “Gut Microbiota”, and “Probiotics” were the search terms used to retrieve the articles. The PRISMA 2009 checklist was applied for article search strategy, article selection, data extraction, and result reporting for the review process. A total of eight original research articles were included from a total of 379 articles obtained in different search strategies. The eight new antimicrobial agents demonstrated significant impacts on the ecological balance of the human intestinal microbiota. Therefore, eubiosis is crucial in preventing the establishment of exogenous antimicrobial-resistant strains as well as their gene transfer.

Systematic review registration

[PRISMA], identifier [2009].

Next-generation membrane-active glycopeptide antibiotics that also inhibit bacterial cell division

Resistance to vancomycin, a life-saving drug against Gram-positive bacterial infections necessitates developing alternative therapeutics. Herein, we report vancomycin derivatives that assimilate mechanisms beyond d-Ala-d-Ala binding. The role of hydrophobicity towards the structure and function of the membrane-active vancomycin showed that alkyl-cationic substitutions favored broad-spectrum activity. The lead molecule, VanQAmC₁₀ delocalized the cell division protein MinD in Bacillus subtilis, implying an impact on bacterial cell division. Further examination of wild-type, GFP-FtsZ, or GFP-FtsI producing- and ΔamiAC mutants of Escherichia coli revealed filamentous phenotypes and delocalization of the FtsI protein. The findings indicate that VanQAmC₁₀ also inhibits bacterial cell division, a property previously unknown for glycopeptide antibiotics. The conjunction of multiple mechanisms contributes to its superior efficacy against metabolically active and inactive bacteria, wherein vancomycin is ineffective. Additionally, VanQAmC₁₀ exhibits high efficacy against methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii in mouse models of infection.

Novel dalbavancin-PLLA implant coating prevents hematogenous Staphylococcus aureus infection in a minimally invasive mouse tail vein model

Infective/bacterial endocarditis is a rare but life-threatening disease with a hospital mortality rate of 22.7% and a 1-year mortality rate of 40%. Therefore, continued research efforts to develop efficient anti-infective implant materials are of the utmost importance. Equally important is the development of test systems that allow the performance of new materials to be comprehensively evaluated. In this study, a novel antibacterial coating based on dalbavancin was tested in comparison to rifampicin/minocycline, and the suitability of a recently developed mouse tail vein model for testing the implant coatings was validated. Small polymeric stent grafts coated with a poly-L-lactic acid (PLLA) layer and incorporated antibiotics were colonized with Staphylococcus (S.) aureus before implantation into the tail vein of mice. The main assessment criteria were the hematogenous spread of the bacteria and the local tissue reaction to the contaminated implant. For this purpose, colony-forming units (CFU) in the blood, spleen and kidneys were determined. Tail cross sections were prepared for histological analysis, and plasma cytokine levels and expression values of inflammation-associated genes were examined. Both antibiotic coatings performed excellently, preventing the onset of infection. The present study expands the range of available methods for testing the anti-infectivity of cardiovascular implants, and the spectrum of agents for effective surface coating.

Role of Extracellular DNA in Dalbavancin Activity against Methicillin-Resistant Staphylococcus aureus (MRSA) Biofilms in Patients with Skin and Soft Tissue Infections

Methicillin-resistant Staphylococcus aureus (MRSA) has become the leading cause of skin and soft tissue infections (SSTIs). Biofilm production further complicates patient treatment, contributing to increased bacterial persistence and antibiotic tolerance. The study aimed to explore the efficacy of different antibiotics on biofilm-producing MRSA isolated from patients with SSTI. A total of 32 MRSA strains were collected from patients with SSTI. The MIC and minimal biofilm eradication concentration (MBEC) were measured in planktonic and biofilm growth. The study showed that dalbavancin, linezolid, and vancomycin all inhibited MRSA growth at their EUCAST susceptible breakpoint. Of the MRSA strains, 87.5% (n = 28) were strong biofilm producers (SBPs), while only 12.5% (n = 4) were weak biofilm producers (WBPs). The MBEC90 values for dalbavancin were significantly lower than those of linezolid and vancomycin in all tested strains. We also found that extracellular DNA (eDNA) contributes to the initial microbial attachment and biofilm formation. The amount of eDNA differed among MRSA strains and was significantly higher in those isolates with high dalbavancin and vancomycin tolerance. Exogenously added DNA increased the MBEC90 and protection of biofilm cells from dalbavancin activity. Of note, the relative abundance of eDNA was higher in MRSA biofilms exposed to MBEC90 dalbavancin than in untreated MRSA biofilms and those exposed to sub-MIC90. Overall, dalbavancin was the most active antibiotic against MRSA biofilms at concentrations achievable in the human serum. Moreover, the evidence of a drug-related increase of eDNA and its contribution to antimicrobial drug tolerance reveals novel potential targets for antibiofilm strategies against MRSA. IMPORTANCE Staphylococcus aureus is the most common cause of skin and soft tissue infections (SSTIs) worldwide. In addition, methicillin-resistant S. aureus (MRSA) is increasingly frequent in postoperative infections and responsible for a large number of hospital readmissions and deaths. Biofilm formation by S. aureus is a primary risk factor in SSTIs, due to a higher antibiotic tolerance. Our study showed that the biofilm-forming capacity varied among MRSA strains, although strong biofilm producers were significantly more abundant than weak biofilm producer strains. Notably, dalbavancin demonstrated a potent antibiofilm activity at concentrations achievable in human serum. Nevertheless, dalbavancin activity was affected by an increased concentration of extracellular DNA in the biofilm matrix. This study provides novel insight for designing more targeted therapeutic strategies against MRSA and to prevent or eradicate harmful biofilms.

Dalbavancin treatment for spondylodiscitis: multi-center clinical experience and literature review

Dalbavancin is a novel lipoglycopeptide antibiotic, characterized by a broad spectrum of activity against Gram-positive cocci. However, its efficacy in spondylodiscitis treatment is not fully established. All adult patients diagnosed with spondylodiscitis and treated with dalbavancin were included across four Italian medical centers from January 2018 to April 2021. We collected clinical and laboratory data, and presented follow-up findings along with a thorough literature review. 13 patients (mean age= 65 years) were included in this study. Dalbavancin was administered as first line treatment in six (46%) of the patients. Reasons for using Dalbavancin included treatment simplification (62%) and clinical failure of previous antibiotics (23%). In general, Dalbavancin was well tolerated with minimal adverse events, and clinical success was achieved in 11/13 (85%) of the patients during hospitalization with additional antibiotics required in the remaining two cases. Five months after discharge, no mortality was observed, however, 42% of patients required additional antibiotics for signs of infection on follow-up imaging. Our study suggests that Dalbavancin could be an effective and safe option in treating spondylodiscitis, however, the scarcity of studies on the topic is concerning. Thus, further studies with large samples and long-term follow-up are warranted to compare the efficacy of Dalbavancin with other available treatment options.

Update on activity of dalbavancin and comparators against clinical isolates of Gram-positive pathogens from Europe and Russia (2017-2018), and on clonal distribution of MRSA

BACKGROUND

Gram-positive pathogens remain a major cause of healthcare- and community-associated infections. In particular, the dissemination of methicillin-resistant staphylococci, as methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE), have significantly reduced the therapeutic options, making the management of these infections even more challenging. Dalbavancin is a second-generation lipoglycopeptide approved for the treatment of moderate to severe acute bacterial skin and skin structure infections (ABSSSIs) caused by Gram-positive organisms, showing a bactericidal effect and a low propensity towards the selection of resistance over time.

AIM

This study aimed to evaluate the antimicrobial activity of dalbavancin and other comparators against recent clinical isolates of Gram-positive pathogens obtained from different sources and from several European countries, including countries of southern and eastern Europe and Russia, where resistance rates are typically high. This study also aimed to describe the clonal relationship of MRSA strains circulating in southern and eastern Europe and Russia.

RESULTS

A total of 1478 isolates were collected. Study results demonstrated the excellent and stable activity of dalbavancin against Gram-positive microorganisms, including MRSA. Interestingly, dalbavancin has retained unaltered MIC₅₀ and MIC₉₀ values over the years and seemed to have a low propensity in selecting resistance mechanisms.

CONCLUSIONS

Our data supported the potential efficacy of dalbavancin against Gram-positive bacteria and uncommon Gram-positive pathogens in patients with ABSSSIs. Of note, few CoNS isolates were resistant to dalbavancin and susceptible to vancomycin, pointing out the importance of testing the susceptibility to dalbavancin before its administration for CoNS infections.

Systematic review and meta-analysis on the safety of dalbavancin

BACKGROUND

Dalbavancin is a semisynthetic lipoglycopeptide antimicrobial agent with activity against Gram-positive bacteria including anaerobes.

RESEARCH DESIGN AND METHODS

Meta-analysis of randomized control trials and large case series (more than 20 patients), were identified by searching Pubmed and Cochrane databases through 14 December 2020.

RESULTS

3,073 patients from 6 RCTs met the inclusion criteria. Treatment emergent adverse effects were described in 30.6% dalbavancin patients, and 38.1% patients with other treatments. Our meta-analysis supports favorable results for dalbavancin treatment (OR 0.79; 95%CI 0.66-0.94; p = 0.01). 2.74% dalbavancin patients had to discontinue treatment versus 2.49% patients on other antibiotics. 4.80% dalbavancin patients versus 5.30% patients with other treatments had severe adverse events. 0.31% in the dalbavancin group and 0.95% receiving other antibiotics died. There was no statistically significant difference in severe adverse effects with OR 0.77; 95% CI 0.52-1.14; p = 0.19. Dalbavancin therapy was shown to have statistically significant lower mortality rate (OR 0.26; 95% CI 0.07-0.90; p = 0.03). Observational studies reported few side effects but included a heterogeneous population of patients concerning their diagnosis and the duration of antibiotic treatment.

CONCLUSIONS

Dalbavancin has comparable safety profile relative to other antibiotics and is well-tolerated.

Dalbavancin for the Treatment of Prosthetic Joint Infections: A Narrative Review

Dalbavancin (DAL) is a lipoglycopeptide with bactericidal activity against a very wide range of Gram-positive microorganisms. It also has unique pharmacokinetic properties, namely a prolonged half-life (around 181 h), which allows a convenient weekly dosing regimen, and good diffusion in bone tissue. These features have led to off-label use of dalbavancin in the setting of bone and joint infection, including prosthetic joint infections (PJI). In this narrative review, we go over the pharmacokinetic and pharmacodynamic characteristics of DAL, along with published in vitro and in vivo experimental models evaluating its activity against biofilm-embedded bacteria. We also examine published experience of osteoarticular infection with special attention to DAL and PJI.

Dalbavancin treatment for prosthetic joint infections in real-life: a national cohort study and literature review

OBJECTIVES

Dalbavancin is a long-lasting lipoglycopeptide active against Gram-positive bacteria, especially methicillin-resistant staphylococci. Few data are available on dalbavancin use for treatment of prosthetic joint infections (PJIs). We describe a cohort of patients treated for PJI with dalbavancin and review the literature regarding this condition.

METHODS

All adult patients with PJI from the French dalbavancin national cohort from 1 June 2017 to 1 January 2019 were included. We collected clinical and microbiological characteristics and outcome through a standardised questionnaire. Clinical cure was defined as absence of clinical signs of infection at last visit. Failure was a composite criterion defined by persistence or reappearance of signs of infection, and/or switch to suppressive antibiotic treatment and/or death from infection. The literature review was performed using PubMed.

RESULTS

Seventeen patients were included. Bacteria were identified in 16 cases: Staphylococcus aureus (n = 10), including methicillin-resistant S. aureus (n = 1); and coagulase-negative staphylococci (n = 10), including methicillin-resistant Staphylococcus epidermidis (n = 4). Sixteen patients (94.1%) had received antibiotic therapy prior to dalbavancin use (mean of 2.2 ± 1.3 lines). Clinical cure was achieved in 8/17 patients after a median follow-up of 299.0 (IQR 97.0-476.0) days. We reviewed all cases of PJI treated with dalbavancin available in the literature and the overall clinical cure was estimated at 73.1%.

CONCLUSION

Our study and literature data suggest that use of dalbavancin in PJI could be considered, even as salvage therapy. Dalbavancin appears to be a safe and easy treatment for patients with staphylococcal PJIs.

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.

The role of dalbavancin for Gram positive infections in the COVID-19 era: state of the art and future perspectives

INTRODUCTION

The COVID-19 pandemic has dramatically challenged the national health systems worldwide in the last months. Dalbavancin is a novel antibiotic with a long plasmatic half-life and simplified weekly administration regimens, thus representing a promising option for the outpatient treatment of Gram-positive infections and the early discharge of hospitalized patients. Dalbavancin is approved for the treatment of acute bacterial skin and skin structure infections (ABSSSIs). Many preliminary data seem to support its use in other indications, such as osteomyelitis, prosthetic joint infections, and infective endocarditis.

AREAS COVERED

A search in the literature using validated keywords (dalbavancin, Gram-positive infections, Gram-positive cocci, ABSSSI, intravenous treatment, and long-acting antibiotics) was conducted on biomedical bibliographic databases (PubMed and Embase) from 2004 to 30 September 2020. Results were analyzed during two consensus conferences with the aim to review the current evidence on dalbavancin in Gram-positive infections, mainly ABSSSI, osteomyelitis, and infective endocarditis, highlight the main limitations of available studies and suggest possible advantages of the molecule.

EXPERT OPINION

The board identifies some specific subgroups of patients with ABSSSIs who could mostly benefit from a treatment with dalbavancin and agrees that the design of homogenous and robust studies would allow a broader use of dalbavancin even in other clinical settings.

Efficacy and mechanism of actions of natural antimicrobial drugs

Microbial infections have significantly increased over the last decades, and the mortality rates remain unacceptably high. The emergence of new resistance patterns and the spread of new viruses challenge the eradication of infectious diseases. The declining efficacy of antimicrobial drugs has become a global public health problem. Natural products derived from natural sources, such as plants, animals, and microorganisms, have significant efficacy for the treatment of infectious diseases accompanied by less adverse effects, synergy, and ability to overcome drug resistance. As the Chinese female scientist Youyou Tu received the Nobel Prize for the antimalarial drug artemisinin, antimicrobial drugs developed from Traditional Chinese Medicine are expected to receive increasing attention again. This review summarizes the antimicrobial agents derived from natural products approved for nearly 20 years and describes their efficacy and mode of action. The aim of this unit is to review the current status of antimicrobial drugs from natural products in order to increase the value of natural products as a source of novel drug candidates for infectious diseases.

Dalbavancin for the Treatment of Complicated Gram-Positive Skin and Soft Tissue Infections

New antimicrobial agents have been developed to treat infections caused by methicillin-resistant Staphylococcus aureus and other multidrug-resistant pathogens. Dalbavancin is a novel semisynthetic lipoglycopeptide antibiotic, particularly active against methicillin-resistant Staphylococcus aureus. Due to its unique pharmacological characteristics and longer half-life, it can be administered once-weekly or every 15 days and in outpatient setting. Currently, it is indicated for complicated skin and soft tissue infections, but accumulating evidence points to its off-label efficacy in osteomyelitis and endocarditis. Further experience is still needed to increase our knowledge on the role of dalbavancin in a wider range of Gram-positive infections requiring prolonged antimicrobial treatment.

The role of dalbavancin in the treatment of acute bacterial skin and skin structure infections (ABSSSIs)

Introduction: Acute bacterial skin and skin-structure infections (ABSSSI) are a subgroup of skin and soft tissue infections and are a common source of morbidity in both the community and the hospital setting. The most common cause of ABSSSI is Staphylococcus aureus, which also includes methicillin-resistant S. aureus (MRSA), together with beta-hemolytic streptococci, enterococci, and Gram-negative bacteria. Since the emergence of MRSA, the management of ABSSSI has become more challenging. Novel therapies alternative to teicoplanin and vancomycin, intravenous agents commonly used against MRSA and employed in hospitalized patients, and to other antibiotics which are used as standard of care for MRSA infection, with a higher efficacy and safer profile are worth evaluating.Areas covered: This review presents and discusses current evidence on the use of dalbavancin in the treatment of ABSSSI.Expert opinion: Dalbavancin represents a promising therapeutic choice in patients with ABSSSI, thanks to its favorable pharmacokinetic profile, valuable antimicrobial spectrum, and good safety profile.

French national cohort of first use of dalbavancin: A high proportion of off-label use

Dalbavancin is a glycopeptide antibiotic with a long half-life, recently marketed in Europe for skin and soft-tissue infections (SSTIs), but its real-life use is not well known. The aim of this study was to describe all first prescriptions in France over an 16-month period. A retrospective study on all adult patients receiving at least one dose of dalbavancin from 1 June 2017 to 31 September 2018 was performed (75 patients from 29 French hospitals). Data were collected via a standard questionnaire. Failure was defined as persistence or reappearance of signs of infection, and/or switch to suppressive antibiotic treatment, and/or death from infection. The main indications were bone and joint infection (BJI) (64.0%), endocarditis (25.3%), and SSTI (17.3%). The main bacteria involved were Staphylococcus aureus (51.4%), including methicillin-resistant S. aureus (MRSA) (19.4%), and coagulase-negative staphylococci (44.4%). Median minimum inhibitory concentrations (MICs) for staphylococci to vancomycin and dalbavancin ranged from 0.875-2.0 mg/L and 0.032-0.064 mg/L, respectively. Dalbavancin was used after a mean of 2.3 ± 1.2 lines of antimicrobial treatment. The main treatment regimens for dalbavancin were a two-dose regimen (1500 mg each) in 38 cases (50.7%) and a single-dose regimen (1500 mg) in 13 cases (17.3%). Overall, at the patient's last visit, clinical cure was observed in 54/68 patients, whilst failure was observed in 14/68 patients. First use of dalbavancin in France was mostly off-label. Most were due to BJI, often as rescue therapy for severe infections. Even in off-label situations, dalbavancin appears safe and effective.

In vitro cytotoxicity and antibiotic application of green route surface modified ferromagnetic TiO2 nanoparticles

The enormous numbers of applications of TiO₂ nanoparticles (NPs) cause concern about their risk to the environment and human health. Consequently, motivated by the necessity of searching for new sources of TiO₂ NPs of low cytotoxicity with antibacterial activity, we synthesized TiO₂ NPs by a green route using a solution of titanium(iv) isopropoxide as a precursor and an aqueous extract of Artocarpus heterophyllus leaf as a reducing and surface modifying agent. We investigated their structure, shape, size, and magnetic properties, and evaluated their antibiotic application and cytotoxicity. The synthesized TiO₂ NPs were applied against two Gram-negative bacteria (E. coli and S. typhimurium) and two Gram-positive bacteria (S. aureus and B. subtilis) to observe their antibacterial activity; and eventually clear zones of inhibition formed by the TiO₂ NPs were obtained. Moreover, after exposing the synthesized TiO₂ NPs to HeLa cells (carcinoma cells) and Vero cells (normal cells), no toxic effect was found up to a dose of 1000 mg L⁻¹, indicating the safe use of the samples up to at least 1000 mg L⁻¹. However, toxic effects on HeLa cells and Vero cells were observed at doses of 2000 mg L⁻¹ and 3000 mg L⁻¹, respectively. These results indicate the safe use of Artocarpus heterophyllus leaf extract mediated synthesized TiO₂ NPs in their potential applications.

Artocarpus heterophyllus leaf extract mediated green synthesized TiO₂ nanoparticles exhibit less toxicity with high antibacterial activity.

Subinhibitory Dalbavancin Attenuates Exotoxin Production from Methicillin-Sensitive and Methicillin-Resistant Staphylococcus aureus In Vitro

This study investigated the effects of subinhibitory doses of the lipoglycopeptide antibiotic dalbavancin on Staphylococcus aureus toxin production in vitroS. aureus toxin production levels were compared to those seen with the natural glycopeptide antibiotic vancomycin and with representative beta-lactam and oxazolidinone antibiotics. While neither dalbavancin nor vancomycin adversely affected toxin production, of these glycopeptide antibiotics, only dalbavancin significantly attenuated toxin production at subinhibitory concentrations. These findings support the recent success of dalbavancin for treatment of staphylococcal infections.

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.

Telavancin: a novel semisynthetic lipoglycopeptide agent to counter the challenge of resistant Gram-positive pathogens

Telavancin (TD-6424), a semisynthetic lipoglycopeptide vancomycin-derivative, is a novel antimicrobial agent developed by Theravance for overcoming resistant Gram-positive bacterial infections, specifically methicillin-resistant Staphylococcus aureus (MRSA). The US Food and Drug Administration (USFDA) had approved telavancin in 2009 for the treatment of complicated skin and skin structure infections (cSSSIs) caused by Gram-positive bacteria, including MRSA (S. aureus, Streptococcus agalactiae, Streptococcus pyogenes, Streptococcus anginosus group, or Enterococcus faecalis). Telavancin has two proposed mechanisms of action. In vitro, telavancin has a rapid, concentration-dependent bactericidal effect, due to disruption of cell membrane integrity. Telavancin has demonstrable in vitro activity against aerobic and anaerobic Gram-positive bacteria. Telavancin and vancomycin have similar spectra of activity. Gram-negative bacteria are usually non-susceptible to telavancin. Telavancin has been successfully tested in various animal models of bacteremia, endocarditis, meningitis, and pneumonia. Phase II Telavancin versus Standard Therapy for Treatment of Complicated Skin and Soft-Tissue Infections due to Gram-Positive Bacteria (FAST 1 and FAST 2) and phase III [Assessment of Telavancin in Complicated Skin and Skin Structure Infections 1 (ATLAS 1 and ATLAS 2)] clinical trials have been conducted for evaluating telavancin's efficacy and safety in cSSSIs. Phase III clinical trials have been carried out for evaluating telavancin's safety and efficacy in nosocomial pneumonia [Assessment of Telavancin for Treatment of Hospital acquired Pneumonia 1 and 2 (ATTAIN 1 and ATTAIN 2)]. A phase II randomized, double-blind, clinical trial has been carried out for evaluating telavancin's safety and efficacy in uncomplicated S. aureus bacteremia [Telavancin for Treatment of Uncomplicated S. aureus Bacteremia (ASSURE)]. Pacemaker lead-related infective endocarditis due to a vancomycin intermediate S. aureus (VISA) strain (non-daptomycin susceptible) was successfully treated with parenteral telavancin for 8 weeks. Telavancin extensively binds to serum albumin (~93%) and has a relatively small volume of distribution. Telavancin is not biotransformed by any cytochrome P450 microsomal enzymes and excreted mainly in the urine. Though well-tolerated, worrisome adverse effects, including renal dysfunction and QTc prolongation are of potential concern. Given its extensive binding to plasma proteins, long half-life, and a long post-antibiotic effect, it represents a promising addition to the therapeutic armamentarium in combating infections caused by resistant Gram-positive pathogens, namely, MRSA.

Dalbavancin: A New Option for the Treatment of Gram-Positive Infections

Objective:

To review the pharmacology, microbiology, chemistry, in vitro susceptibility, pharmacokinetics, clinical efficacy, safety, tolerability, dosage, and administration of dalbavancin, a new semisynthetic lipoglycopeptide.

Data Sources:

A MEDLINE search, restricted to the English language, was conducted from 1966 through January 2006. Supplementary sources included program abstracts from the Interscience Conference on Antimicrobial Agents and Chemotherapy, American Society of Microbiology, and the Infectious Diseases Society of America from 2000 to 2005 and information available from the manufacturer's Web site.

Study Selection and Data Extraction:

In vitro and preclinical studies, as well as Phase I, II, and III clinical trials, were evaluated to summarize the microbiology, pharmacology, clinical efficacy, and safety of dalbavancin. All published trials and abstracts citing dalbavancin were selected.

Data Synthesis:

Dalbavancin, a novel lipoglycopeptide, has a mechanism of action similar to that of other glycopeptides. It has in vitro activity against a variety of gram-positive organisms, but no activity against gram-negative or vancomycin-resistant enterococci that possess VanA gene. Due to its prolonged half-life (6–10 days), dalbavancin can be administered intravenously once weekly. In Phase II and III clinical trials, dalbavancin was effective and well tolerated for the treatment of skin and soft-tissue infections, catheter-related bloodstream infections, and skin and skin-structure infections. To date, adverse events are mild and limited; the most common include pyrexia, headache, nausea, oral candidiasis, diarrhea, and constipation.

Conclusions:

Dalbavancin appears to be a promising antimicrobial agent for the treatment of gram-positive infections. A new drug application was filed with the Food and Drug Administration (FDA) in December 2004. The FDA issued an approvable letter in 2005 for dalbavancin. If approved, dalbavancin is expected to be launched in the first quarter of 2006.

Dalbavancin reduces biofilms of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE)

Activity of dalbavancin against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) in biofilm was investigated and the microbicidal biofilm concentrations (MBC) were determined. Biofilms obtained from ten MRSA and ten MRSE bloodstream isolates, collected from patients in the General Hospital of Vienna between 2012 and 2015, were incubated with dalbavancin in trypticase soy broth (TSB) in serial dilution from 0.0625 mg/l to 256 mg/l using a microtiter plate biofilm model. The plates were incubated for 24 h at 37 ° C and 50% humidity. Biofilms were fixed with 2.5% glutaraldehyde and stained with crystal violet. Subsequently the optical density (OD₆₂₀) was used to measure the MBC, defined as the concentration of dalbavancin leading to a 50% reduction of biofilm. MBC for MRSA was 1 mg/l–4 mg/l (minimal inhibitory concentrations (MIC) 0.0312 mg/l–0.064 mg/l). MBC for MRSE was 2 mg/l–16 mg/l (MIC 0.023 mg/l–0.0625 mg/l). Dalbavancin successfully reduced MRSA and MRSE in biofilms, and therefore provides a promising option for the treatment of biofilm-associated infections.

Clinical efficacy of dalbavancin for the treatment of acute bacterial skin and skin structure infections (ABSSSI)

Acute bacterial skin and skin structure infections (ABSSSI) are a common disease causing patients to seek treatment through the health care system. With the continued increase of drug-resistant bacterial pathogens, these infections are becoming more difficult to successfully cure. Lipoglycopeptides have unique properties that allow the drug to remain active toward both common and challenging pathogens at the infected site for lengthy periods of time. Dalbavancin, a new lipoglycopeptide, provides two unique dosing regimens for the treatment of ABSSSI. The original regimen of 1,000 mg intravenous infusion followed by a 500 mg intravenous infusion after a week has been shown as safe and effective in multiple, randomized noninferiority trials. These studies also demonstrated that dalbavancin was similar to standard regimens in terms of both safety and tolerability. Recently a single 1,500 mg dose was demonstrated to be equivalent to the dalbavancin two-dose regimen for treating ABSSSI. With the introduction of dalbavancin, clinicians have the option to provide an intravenous antimicrobial agent shown to be as effective as traditional therapies, without requiring admission into the hospitals or prescribing a medication which may not be utilized optimally. Further understanding of dalbavancin and its unusual properties can provide unique treatment situations with potential benefits for both the patient and the overall health care system, which should be further explored.

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.

In vitro activity of dalbavancin against biofilms of staphylococci isolated from prosthetic joint infections

The in vitro activity of dalbavancin was tested against biofilms of 171 staphylococci associated with prosthetic joint infection. Dalbavancin minimum biofilm bactericidal concentration (MBBC) values were: MBBC50 for Staphylococcus aureus and Staphylococcus epidermidis, 1μg/mL; MBBC90 for S. aureus, 2μg/mL; MBBC90 for S. epidermidis, 4μg/mL.

Dalbavancin (BI-387) for the treatment of complicated skin and skin structure infection

In the era of increasing antibiotic resistance, development of new agents that could provide therapeutic options for difficult to treat pathogens is vital. Dalbavancin is a new lipoglycopeptide recently approved by the US FDA for the treatment of acute bacterial skin and skin structure infections. A derivative of the older glycopeptide class, chemical structure alterations resulted in a molecule with a similar mechanism of action, however, with a comparatively increased activity as reflected by organism MICs. These modifications also resulted in an antibiotic with distinctive properties that allow for once-weekly dosing in the treatment of Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus and drug resistant Streptococcus spp. As the first of these long acting compounds, understanding the pharmacokinetic and pharmacodynamic properties of agents like dalbavancin is essential for determining a place in therapy.

Dalbavancin for the treatment of acute bacterial skin and skin structure infections

INTRODUCTION

Acute bacterial skin and skin structure infections (ABSSSI) have increased in incidence and severity. The involvement of resistant organisms, particularly methicillin-resistant Staphylococcus aureus, presents additional challenges. The lipoglycopeptide dalbavancin has a prolonged half-life, high protein binding, and excellent tissue levels which led to its development as a once-weekly treatment for ABSSSI. In the pivotal DISCOVER 1 and DISCOVER 2 trials, dalbavancin proved non-inferior to vancomycin followed by linezolid when used sequentially for ABSSSI, forming the basis for its recent approval in the US and Europe for ABSSSI.

AREAS COVERED

A literature search of published pharmacologic and clinical data was conducted to review the chemistry, pharmacodynamics, and pharmacokinetics of dalbavancin. We also discuss its development process, highlighting efficacy and safety data from pertinent clinical trials and the role it could play in the current clinical landscape.

EXPERT OPINION

DISCOVER 1 and DISCOVER 2 demonstrated dalbavancin's non-inferiority to vancomycin followed by linezolid for ABSSSI and confirmed its safety and tolerability. They were among the first trials to use new, early primary efficacy endpoints, and dalbavancin was among the first agents designated a Qualified Infectious Disease Product for expedited review. Dalbavancin may prove to be a valuable option for ABSSSI patients in whom conventional therapy is limited.

Treatment of methicillin-sensitive Staphylococcus aureus bacteremia secondary to septic phlebitis using dalbavancin

WHAT IS KNOWN AND OBJECTIVE

Treatment of bacteremia due to Staphylococcus aureus often requires prolonged therapy leading to increased hospital lengths of stay and associated costs. For certain patients, referral to an outpatient parenteral antimicrobial therapy (OPAT) programme serves as an alternative to increased inpatient length of stay. We report an alternative to OPAT using dalbavancin for the treatment of methicillin-sensitive Staphylococcus aureus (MSSA).

CASE SUMMARY

A 54-year-old Caucasian man was brought to the emergency department from a rehabilitation centre with altered mental status and possible seizure. A peripheral intravenous catheter was placed in the left forearm, and the patient was transferred to the intensive care unit (ICU) for management of his acute psychosis, possible seizure and hyponatremia. Seven days into admission, the patient became febrile thought to be secondary to septic phlebitis of the forearm. Blood cultures were taken and organism identification using Nanosphere Verigene^® BC-GP rapid diagnostic testing resulted in MSSA. The patient received treatment with cefazolin with a planned treatment duration of 14 days but because of the patient's history of alcohol abuse, psychosis requiring hospitalization via the Baker Act, and history of non-compliance to follow-up appointments, the patient was deemed ineligible for OPAT. Due to the limited treatment options, therapy for MSSA bacteremia was changed on day 6 of cefazolin therapy to dalbavancin to complete the 14-day treatment duration. Blood cultures were negative at the end of treatment and no relapse of infection occurred.

WHAT IS NEW AND CONCLUSION

To our knowledge, this is the first case report using dalbavancin in clinical practice for the treatment of MSSA bacteremia secondary to septic phlebitis. This report highlights the potential role of the newer lipoglycopeptides, such as dalbavancin, in treating patients who require long-term parenteral antimicrobial therapy and are ineligible for treatment via OPAT.

Pharmacokinetics, Safety and Tolerability of Single Dose Dalbavancin in Children 12-17 Years of Age

BACKGROUND

Dalbavancin is a lipoglycopeptide antibiotic with Gram-positive activity and novel pharmacokinetic (PK) properties that result in a prolonged terminal half-life of 15.5 days in adults. Once weekly dosing in adults in phase 3 studies of complicated skin and skin structure infections documented dalbavancin exposures associated with clinical and microbiologic efficacy. PK properties have not been examined in children. The primary objective of this open-label, multicenter single-dose phase 1 study was to characterize the PK of dalbavancin in hospitalized pediatric subjects 12-17 years of age.

METHODS

A single dose of 1000 mg of dalbavancin (the standard adult dose) was administered as a 30-minute intravenous infusion to subjects weighing 60 kg or greater and 15 mg/kg for subjects weighing <60 kg. A noncompartmental PK analysis was performed.

RESULTS

The apparent terminal t1/2 was approximately 9 days and was similar for dalbavancin dosages of 1000 mg and 15 mg/kg. Median dalbavancin plasma exposures (Cmax and AUCinf) when administered as 1000 mg to subjects weighing 60 kg or greater were similar to those when dalbavancin was administered at 15 mg/kg to subjects weighing <60 kg and slightly lower than exposures in adults given 1000 mg in prior PK and treatment studies. Single dose dalbavancin was well tolerated.

CONCLUSIONS

Given dalbavancin exposures documented in children 12-17 years of age, and recognized dose proportionality, appropriate dosing can be modeled for pediatric phase 3 trials in acute bacterial skin and skin structure infections, to achieve the same exposure that is reported to be safe and effective in adults.

Monte Carlo simulation analysis of ceftobiprole, dalbavancin, daptomycin, tigecycline, linezolid and vancomycin pharmacodynamics against intensive care unit-isolated methicillin-resistant Staphylococcus aureus

The aim of the present study was to compare the potential of ceftobiprole, dalbavancin, daptomycin, tigecycline, linezolid and vancomycin to achieve their requisite pharmacokinetic/pharmacodynamic (PK/PD) targets against methicillin-resistant Staphylococcus aureus isolates collected from intensive care unit (ICU) settings. Monte Carlo simulations were carried out to simulate the PK/PD indices of the investigated antimicrobials. The probability of target attainment (PTA) was estimated at minimum inhibitory concentration values ranging from 0.03 to 32 μg/mL to define the PK/PD susceptibility breakpoints. The cumulative fraction of response (CFR) was computed using minimum inhibitory concentration data from the Canadian National Intensive Care Unit study. Analysis of the simulation results suggested the breakpoints of 4 μg/mL for ceftobiprole (500 mg/2 h t.i.d.), 0.25 μg/mL for dalbavancin (1000 mg), 0.12 μg/mL for daptomycin (4 mg/kg q.d. and 6 mg/kg q.d.) and tigecycline (50 mg b.i.d.), and 2 μg/mL for linezolid (600 mg b.i.d.) and vancomycin (1 g b.i.d. and 1.5 g b.i.d.). The estimated CFR were 100, 100, 70.6, 88.8, 96.5, 82.4, 89.4, and 98.3% for ceftobiprole, dalbavancin, daptomycin (4 mg/kg/day), daptomycin (6 mg/kg/day), linezolid, tigecycline, vancomycin (1 g b.i.d.) and vancomycin (1.5 g b.i.d.), respectively. In conclusion, ceftobiprole and dalbavancin have the highest probability of achieving their requisite PK/PD targets against methicillin-resistant Staphylococcus aureus isolated from ICU settings. The susceptibility predictions suggested a reduction of the vancomycin breakpoint to 1 μg/mL.

Alpha amylase assisted synthesis of TiO₂ nanoparticles: structural characterization and application as antibacterial agents

The enzyme alpha amylase was used as the sole reducing and capping agent for the synthesis of TiO2 nanoparticles. The biosynthesized nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopic (TEM) methods. The XRD data confirms the monophasic crystalline nature of the nanoparticles formed. TEM data shows that the morphology of nanoparticles depends upon the enzyme concentration used at the time of synthesis. The presence of alpha amylase on TiO2 nanoparticles was confirmed by FTIR. The nanoparticles were investigated for their antibacterial effect on Staphylococcus aureus and Escherichia coli. The minimum inhibitory concentration value of the TiO2 nanoparticles was found to be 62.50 μg/ml for both the bacterial strains. The inhibition was further confirmed using disc diffusion assay. It is evident from the zone of inhibition that TiO2 nanoparticles possess potent bactericidal activity. Further, growth curve study shows effect of inhibitory concentration of TiO2 nanoparticles against S. aureus and E. coli. Confocal microscopy and TEM investigation confirm that nanoparticles were disrupting the bacterial cell wall.

Membrane active vancomycin analogues: a strategy to combat bacterial resistance

The alarming growth of antibiotic resistant superbugs such as vancomycin-resistant Enterococci and Staphylococci has become a major global health hazard. To address this issue, we report the development of lipophilic cationic vancomycin analogues possessing excellent antibacterial activity against several drug-resistant strains. Compared to vancomycin, efficacy greater than 1000-fold was demonstrated against vancomycin-resistant Enterococci (VRE). Significantly, unlike vancomycin, these compounds were shown to be bactericidal at low concentrations and did not induce bacterial resistance. An optimized compound in the series, compared to vancomycin, showed higher activity in methicillin-resistant Staphylococcus aureus (MRSA) infected mouse model and exhibited superior antibacterial activity in whole blood with no observed toxicity. The remarkable activity of these compounds is attributed to the incorporation of a new membrane disruption mechanism into vancomycin and opens up a great opportunity for the development of novel antibiotics.

Dalbavancin, a long-acting lipoglycopeptide for the treatment of multidrug-resistant Gram-positive bacteria

Dalbavancin is a new lipoglycopeptide antibiotic in late-stage clinical development as a once-weekly treatment for serious infections including skin and skin structure infections. Its in vitro potency is greater than that of vancomycin, with a MIC(90) of 0.06 mg/l for Staphylococcus aureus and coagulase-negative staphylococci (irrespective of oxacillin susceptibility), 0.06-0.12 mg/l for vancomycin-susceptible Enterococcus spp. and 0.003 mg/l or less for Streptococcus pneumoniae or beta-hemolytic streptococci. Dalbavancin has dual routes of elimination. The results of Phase II/III studies show clinical efficiency in complicated skin and skin structure infection. During clinical trials, dalbavancin was as effective as linezolid or vancomycin in the treatment of patients with complicated skin and skin structure infection, including those with methicillin-resistant S. aureus. An additional Phase II study demonstrated efficacy in catheter-related bacteremia. Other preliminary in vitro and in vivo data have identified putative interest of dalbavancin in endocarditis, osteitis, diabetic foot, respiratory tract or joint infection.

Role of linezolid in the treatment of complicated skin and soft tissue infections

Staphylococcus aureus is the most common cause of complicated skin and soft tissue infections (cSSTIs). Antibiotic choices for these infections continue to evolve. History has seen penicillin progress to antistaphylococcal penicillins and cephalosporins, but these drugs are now giving way to drugs that are effective against methicillin-resistant S. aureus (MRSA). While vancomycin has been the gold standard to treat MRSA infections, newer therapeutic options have been developed over the last 5 years. These include quinupristin-dalfopristin, daptomycin, tigecycline and linezolid, which is the focus for this review. Linezolid is efficacious in the treatment of cSSTIs (including diabetic foot infections) caused by Gram-positive organisms (including MRSA), with a well-defined safety profile and straightforward dosing. It is also approved for nosocomial pneumonia, community-acquired pneumonia and uncomplicated skin and skin structure infections. Linezolid has an oral and parenteral formulation, which are equivalent. The oral formulation has the potential to offer economic benefits as compared with other therapies. Currently, there are only a few new antibiotics in development with MRSA activity. The proper use of all antibiotics, including these newer agents, is increasingly important if we are to slow the evolution of microbial resistance.

Antimicrobial Spectrum and Potency of Dalbavancin Tested Against Clinical Isolates from Europe and North America (2003): Initial Results from an International Surveillance Protocol

Dalbavancin is a bactericidal dimethylaminopropyl amide glycopeptide derivative possessing an extended serum elimination half-life in humans that allows once-weekly dosing for the therapy of Gram-positive infections. Strains from this baseline surveillance protocol in North America (NA; USA and Canada) and Europe (EU, 14 countries) were sampled in 2003. A total of 7,765 Gram-positive isolates (3,695 from NA and 4,070 from EU) were tested by reference broth microdilution methods against dalbavancin and 10 comparator agents. Species were analyzed separately by resistance phenotypes such as methicillin- (oxacillin-) resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and penicillin-resistant Streptococcus pneumoniae. Dalbavancin and other glycopeptides were very active against staphylococci (n=4648) with dalbavancin being 16- to 32-fold more potent than vancomycin (MIC90, 0.06 versus 2 mg/L). MRSA rates were greater (31.6%) in NA than in EU (26.1%). Quinupristin/dalfopristin resistance (MIC, > or = 2 mg/L; 0.1-0.5%) was documented more often in EU compared to NA. Dalbavancin (MIC50, 0.03-0.06 mg/L) was active against enterococci, except VanA resistance phenotypes. VRE rates were lower in EU (8.3%) then in NA (35.9%) from this resistance-enhanced enterococcal collection. Streptococci (dalbavancin MIC90, 0.016-0.03 mg/L) were generally most susceptible to glycopeptides (100.0%), quinupristin/dalfopristin (98.6-100.0%) and linezolid (100.0%); but dalbavancin was 16-fold more active than comparators. All vancomycin-susceptible enterococci and > 90% of vanB VRE had dalbavancin MIC values at < or = 1 mg/L,but vanA VRE strains had dalbavancin MIC results ranging from 0.06 to > 8 mg/L (median MIC, > or = 8 mg/L). Dalbavancin MIC values were not adversely influenced by geographic region or resistance phenotype (except vanA VRE). Infrequently isolated Gram-positive organisms such as Bacillus spp. (MIC90, 0.12 mg/L), Corynebacterium spp. (MIC90, 0.12 mg/L), Listeria monocytogenes (MIC90, 0.25 mg/L) and Micrococcus spp. (MIC90, 0.03 mg/L) were very susceptible to dalbavancin. In conclusion, these 2003 baseline resistance surveillance findings confirm the potent dalbavancin activity compared to several comparator agents against important Gram-positive pathogens. This high volume international survey indicates potential therapeutic roles for dalbavancin against many troublesome resistant Gram-positive phenotypes.

Population Pharmacokinetic Analysis of Dalbavancin, a Novel Lipoglycopeptide

Dalbavancin is a lipoglycopeptide antibiotic in clinical development as a once-weekly treatment for serious infections. A total of 532 patients, consisting of 502 patients with skin and soft tissue infections requiring parenteral therapy and 30 patients with catheter-related bloodstream infections, was available for population pharmacokinetic analysis. The majority of patients (78.4%) received dalbavancin intravenously as a 1000-mg dose on day 1 and a single 500-mg dose on day 8. A 2-compartment model with first-order elimination provided the best fit to the data. The clearance of dalbavancin was influenced by body surface area and creatinine clearance, but together they described less than 25% of the interpatient variability. Body surface area was determined to be a predictor of the central volume of distribution. There was no evidence that the presence of metabolic substrates, inhibitors, or inducers of cytochrome P450 or selected concomitant medications influenced the clearance of dalbavancin.

Comprehensive update of dalbavancin activity when tested against uncommonly isolated streptococci, Corynebacterium spp., Listeria monocytogenes, and Micrococcus spp. (1357 strains)

Dalbavancin is an investigational lipoglycopeptide having an extended serum elimination half-life allowing once-weekly dosing. Data from testing 1357 strains of uncommonly isolated species expand the dalbavancin spectrum details as follows (MIC50/90): β-haemolytic streptococcal serogroups C, F, and G (≤0.03/≤0.03 μg/mL), 7 viridans group of streptococci (≤0.03/≤0.03-0.06 μg/mL), 5 Corynebacterium spp. (0.06/0.12 μg/mL), Listeria monocytogenes (0.06/0.12 μg/mL), and Micrococcus spp. (≤0.03/≤0.03 μg/mL). Among all reported isolates, 99.8% of tested strains were inhibited at dalbavancin MIC values at ≤0.12 μg/mL. Dalbavancin remains very potent against rarer Gram-positive pathogens, using in vitro test experience with organisms cultured through 2011.