Non-faecium non-faecalis enterococci: a review of clinical manifestations, virulence factors, and antimicrobial resistance

SUMMARYEnterococci are a diverse group of Gram-positive bacteria that are typically found as commensals in humans, animals, and the environment. Occasionally, they may cause clinically relevant diseases such as endocarditis, septicemia, urinary tract infections, and wound infections. The majority of clinical infections in humans are caused by two species: Enterococcus faecium and Enterococcus faecalis. However, there is an increasing number of clinical infections caused by non-faecium non-faecalis (NFF) enterococci. Although NFF enterococcal species are often overlooked, studies have shown that they may harbor antimicrobial resistance (AMR) genes and virulence factors that are found in E. faecium and E. faecalis. In this review, we present an overview of the NFF enterococci with a particular focus on human clinical manifestations, epidemiology, virulence genes, and AMR genes.

Recent development and fighting strategies for lincosamide antibiotic resistance

SUMMARYLincosamides constitute an important class of antibiotics used against a wide range of pathogens, including methicillin-resistant Staphylococcus aureus. However, due to the misuse of lincosamide and co-selection pressure, the resistance to lincosamide has become a serious concern. It is urgently needed to carefully understand the phenomenon and mechanism of lincosamide resistance to effectively prevent and control lincosamide resistance. To date, six mobile lincosamide resistance classes, including lnu, cfr, erm, vga, lsa, and sal, have been identified. These lincosamide resistance genes are frequently found on mobile genetic elements (MGEs), such as plasmids, transposons, integrative and conjugative elements, genomic islands, and prophages. Additionally, MGEs harbor the genes that confer resistance not only to antimicrobial agents of other classes but also to metals and biocides. The ultimate purpose of discovering and summarizing bacterial resistance is to prevent, control, and combat resistance effectively. This review highlights four promising strategies, including chemical modification of antibiotics, the development of antimicrobial peptides, the initiation of bacterial self-destruct program, and antimicrobial stewardship, to fight against resistance and safeguard global health.

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.

Dalbavancin for Acute Bacterial Skin and Skin Structure Infections in Pediatrics: Insights from Continuation Therapy Experience

Acute Bacterial Skin and Skin Structure Infections (ABSSSI) are marked by substantial morbidity, frequent need for hospitalization, and long courses of intravenous antibiotic therapy. Herein, we report four cases of pediatric patients admitted for ABSSSI and managed with a combination antibiotic regimen incorporating dalbavancin: a second-generation lipoglycopeptide active against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus. In our experience, particularly in a setting with a high methicillin-resistance rate, dalbavancin demonstrated safety and efficacy, simplifying ABSSSI management in childhood. Its prolonged half-life enables a single-dose administration regimen, offering potential solutions to numerous challenges encountered in pediatric care, such as extended hospital stays, difficulties in securing and maintaining vascular access, lack of pediatric-specific drug indications, and limited availability of suitable oral formulations.

Experience with dalbavancin use in various gram-positive infections within Aberdeen Royal Infirmary OPAT service

PURPOSE

Dalbavancin, approved in 2014 for Gram-positive acute bacterial skin and skin structure infections (ABSSSI), has pharmacokinetics enabling treatment with one or two doses. Dalbavancin might be useful in outpatient parenteral antibiotic therapy (OPAT) of deep-seated infections, otherwise requiring inpatient admission. We documented our experience with pragmatic dalbavancin use to assess its effectiveness for varied indications, on- and off-label, as primary or sequential consolidation therapy.

METHODS

Patients prescribed dalbavancin between 1 December 2021 and 1 October 2022 were screened for demographics of age, sex, Charlson comorbidity index (CCI), allergies, pathogens, doses of dalbavancin, other antibiotics administered and surgery. Where available, infection markers were recorded. The primary outcome was a cure at the end of treatment. Secondary outcomes included any adverse events and for those with treatment failures, response to salvage antibiotics.

RESULTS

Sixty-seven per cent of patients were cured. Cure rates by indication were 93% for ABSSSI, 100% for bacteraemia, 90% for acute osteomyelitis, 0% for chronic osteomyelitis, 75% for native joint septic arthritis and 33% for prosthetic joint infection. Most bone and joint infections that were not cured did not have source control, and the goal of treatment was suppressive. Successful suppression rates were greater at 48% for chronic osteomyelitis and 66% for prosthetic joint infections. Adverse events occurred in 14 of 102 patients.

CONCLUSION

This report adds to clinical experience with dalbavancin for off-label indications whilst further validating its role in ABSSSI. Dalbavancin as primary therapy in deep-seated infections merits investigation in formal clinical trials.

Antibiotic Resistance to Molecules Commonly Prescribed for the Treatment of Antibiotic-Resistant Gram-Positive Pathogens: What Is Relevant for the Clinician?

Antibiotic resistance in Gram-positive pathogens is a relevant concern, particularly in the hospital setting. Several antibiotics are now available to treat these drug-resistant pathogens, such as daptomycin, dalbavancin, linezolid, tedizolid, ceftaroline, ceftobiprole, and fosfomycin. However, antibiotic resistance can also affect these newer molecules. Overall, this is not a frequent phenomenon, but it is a growing concern in some settings and can compromise the effectiveness of these molecules, leaving few therapeutic options. We reviewed the available evidence about the epidemiology of antibiotic resistance to these antibiotics and the main molecular mechanisms of resistance, particularly methicillin-resistant Sthaphylococcus aureus, methicillin-resistant coagulase-negative staphylococci, vancomycin-resistant Enterococcus faecium, and penicillin-resistant Streptococcus pneumoniae. We discussed the interpretation of susceptibility tests when minimum inhibitory concentrations are not available. We focused on the risk of the emergence of resistance during treatment, particularly for daptomycin and fosfomycin, and we discussed the strategies that can be implemented to reduce this phenomenon, which can lead to clinical failure despite appropriate antibiotic treatment. The judicious use of antibiotics, epidemiological surveillance, and infection control measures is essential to preserving the efficacy of these drugs.

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.

In vitro activity of ceftobiprole and dalbavancin against a collection of coagulase-negative staphylococci isolates from clinical samples with reduced susceptibility to daptomycin and/or resistant to linezolid or glycopeptides

INTRODUCTION

The aim was to investigate the in vitro activity of ceftobiprole and dalbavancin against a collection of coagulase-negative staphylococci (CoNS) isolates with reduced susceptibility to daptomycin or resistant to linezolid and/or glycopeptides.

METHODS

A total of 228 CoNS were tested using the Vitek-2 AST-626 cards (bioMérieux) and MIC of daptomycin, linezolid, vancomycin and teicoplanin were confirmed by Etest Strips (bioMérieux). Susceptibility testing for ceftobiprole and dalbavancin were performed by CLSI broth microdilution methodology. Results were interpreted according to 2021 EUCAST clinical breakpoints.

RESULTS

Ceftobiprole and dalbavancin were active against 96.0% and 93.0% of CoNS, respectively, MIC90 were 2 and 0.125mg/L. MICs of ceptobiprole were higher against S. hominis and S. haemolyticus (MIC90 4mg/L). Dalbavancin exhibited higher MICs against S. haemolyticus and CoNS with reduced susceptibility to daptomycin and resistant to teicoplanin.

CONCLUSION

Ceftobiprole and dalbavancin demonstrated a high in vitro activity against our collection of CoNS isolates.

A Narrative Review on the Role of Dalbavancin in the Treatment of Bone and Joint Infections

Bone and joint infections (BJI) require prolonged antimicrobial treatment, leading to lengthy hospitalizations, high costs, the risk of nosocomial infections, and the development of antimicrobial resistance. Dalbavancin is a novel semisynthetic lipoglycopeptide approved for the treatment of adults and children with acute bacterial skin and skin structure infections. This narrative review aims to summarize the characteristics of dalbavancin and the current scientific evidence regarding its clinical efficacy and safety in the treatment of BJI. A literature search until June 2023 was performed to identify all published research about the role of dalbavancin in the management of BJI. Due to its unique pharmacokinetics characterized by prolonged half-life, high bactericidal activity against most Gram-positive bacteria, a good safety profile, and high tissue penetration, dalbavancin can be a valuable alternative to the treatment of BJI. Clinical studies have shown its non-inferiority compared to conventional therapies in BJI, offering potent activity against key pathogens and an extended dosing interval that may shorten hospitalization. In conclusion, dalbavancin represents a promising treatment option for BJI with a favorable safety profile, but further research in both adults and particularly children, who are ideal candidates for long-acting antibiotics, is necessary to evaluate the role of dalbavancin in BJI.

Comparative In Vitro Activity of New Lipoglycopeptides and Vancomycin Against Ocular Staphylococci and Their Toxicity on the Human Corneal Epithelium

PURPOSE

The purpose of this study was to assess the potential of new lipoglycopeptides as novel topical therapies for improved treatment of recalcitrant ocular infections. We evaluated the in vitro antimicrobial activity of oritavancin, dalbavancin, and telavancin compared with vancomycin (VAN) against a large collection of ocular staphylococcal isolates and their cytotoxicity on human corneal epithelial cells (HCECs).

METHODS

Antimicrobial susceptibility testing was performed by broth microdilution against 223 Staphylococcus spp. clinical isolates. Time-kill kinetics were determined for methicillin-resistant strains of Staphylococcus aureus (MRSA) (n = 2) and Staphylococcus epidermidis (MRSE) (n = 1). In vitro cytotoxicity assays were performed with AlamarBlue and live/dead staining on HCECs.

RESULTS

All new lipoglycopeptides showed strong in vitro potency against ocular staphylococci, including multidrug-resistant MRSA strains, with dalbavancin showing a slightly higher potency overall [minimum inhibitory concentration (MIC) 90 0.06 μg/mL] compared with telavancin and oritavancin (MIC 90 0.12 μg/mL), whereas VAN had the lowest potency (MIC 90 2 μg/mL). Oritavancin exerted rapid bactericidal activity within 1 h for MRSA and 2 h for MRSE. All other drugs were bactericidal within 24 h. At a concentration commonly used for topical preparations (25 mg/mL), cytotoxicity was observed for VAN after 5 min of incubation, whereas reduction in HCEC viability was not seen for telavancin and was less affected by oritavancin and dalbavancin. Cytotoxicity at 25 mg/mL was seen for all drugs at 30 and 60 min but was significantly reduced or undetected for lower concentrations.

CONCLUSIONS

Our study demonstrates that new lipoglycopeptides have substantially better in vitro antimicrobial activity against ocular staphylococcal isolates compared with VAN, with a similar or improved toxicity profile on HCECs.

Acute bacterial skin and skin structure infections in pediatric patients: potential role of dalbavancin

INTRODUCTION

Acute bacterial skin and skin structure infections (ABSSSIs) are a subtype of skin and soft tissue infections (SSTI), usually sustained by Gram-positive bacteria, whose incidence is high among children. ABSSSIs are responsible for a considerable number of hospitalizations. Moreover, as multidrug resistant (MDR) pathogens become widespread, the pediatric category seems burdened with an increased risk of resistance and treatment failure.

AREAS COVERED

To obtain a view on the status of the field, we describe the clinical, epidemiological, and microbiological aspects of ABSSSI in children. Old and new treatment options were critically revised with a focus on the pharmacological characteristics of dalbavancin. Evidence on the use of dalbavancin in children was collected, analyzed, and summarized.

EXPERT OPINION

Many of the therapeutic options available at the moment are characterized by the need for hospitalization or repeated intravenous infusions, safety issues, possible drug-drug interactions, and reduced efficacy on MDRs. Dalbavancin, the first long-acting molecule with strong activity against methicillin-resistant and also many vancomycin-resistant pathogens represents a game changer for adult ABSSSI. In pediatric settings, the available literature is still limited, but a growing body of evidence supports dalbavancin use in children with ABSSSI, demonstrating this drug to be safe and highly efficacious.

Dalbavancin in clinical practice in Spain: a 2 year retrospective study

Objectives

Dalbavancin is approved for the treatment of acute bacterial skin and skin-structure infections (ABSSSIs) in adults. Its unique pharmacokinetic properties allow daily dosing to be avoided. The objective was to describe the sociodemographic and clinical characteristics of patients treated with dalbavancin in Spain, and to evaluate its effectiveness and safety in real-world settings.

Patients and methods

This non-interventional, retrospective, observational and multicentre study included patients who received at least one dose between 2018 and 2019 in seven Spanish hospitals.

Results

In total, 187 patients were included. The most common comorbidities were cardiovascular disease (27.4%) and diabetes mellitus (23.5%). Dalbavancin was used to treat osteoarticular infections (28.3%), ABSSSIs (22.5%), cardiovascular infections (20.9%) and catheter-related infections (18.2%). The most prevalent pathogens were Staphylococcus aureus (34.2%), CoNS (32.6%), and enterococci (12.8%). The main reason for use was early hospital discharge (65.8%). Most patients were treated with 1500 mg in a single dose (35.3%) and the median duration of treatment was 2 weeks. The treatment was clinically successful in 91.4% of cases. Six patients (3.2%) reported adverse events. Physicians agreed on the potential reduction of hospitalization days (85.3%). A subanalysis of patient characteristics and type of pathogen showed similar results in terms of efficacy and safety.

Conclusions

Dalbavancin seems to be effective and safe as second-line treatment in severe Gram-positive infections. It improves treatment adherence and allows outpatient management. Furthermore, the effectiveness and safety profile are maintained against diverse microorganisms in Gram-positive infections and regardless of the patients' comorbidities at baseline, or age.

Tackling Extended Hospital Stays in Patients with Acute Bacterial Skin and Skin Structure Infections

Hospitalisation rates for acute bacterial skin and skin structure infection (ABSSSI) are rising and represent a large pharmacoeconomic burden as treatment may involve an extended number of days of antibiotic therapy. This article first aims to provide a review of treatment challenges associated with ABSSSIs in both hospital and outpatient settings, and shows that while more traditionally treatment has been conducted in a hospital setting, for a number of patients, a variety of considerations, including pharmacoeconomics, infection control, and patient preference, has led to the development of recommendations to assess the eligibility of patients for early discharge from hospital to complete their antibiotic regimen in the outpatient setting. However, such patients require monitoring for drug adherence to oral regimens or complications associated with daily intravenous administration, such as injection site reactions and infection. This review also focuses on one of a number of new antibiotics for ABSSSI, dalbavancin, as the long-acting glycopeptide with the most clinical experience to date. This antibiotic has been shown to be as effective as a daily/twice daily regimen with similar safety profiles. Health economic analysis of dalbavancin is also presented. It has shown that in some, though not all, clinical settings a reduction in the overall treatment cost is evident as, despite a higher medication cost, the lower hospitalisation time can lead to greater cost savings. In conclusion, while the burden of ABSSSI is rising, new treatment options provide additional therapeutic choice, although pharmacoeconomic considerations might limit use in some cases.

Comparative efficacy of dalbavancin alone and with rifampicin against in vitro biofilms in a pharmacodynamic model with methicillin-resistant Staphylococcus aureus

BACKGROUND

The anti-biofilm efficacy of dalbavancin has been evaluated in static models. Using an in vitro pharmacokinetic/pharmacodynamic model, we evaluated the comparative activity of dalbavancin alone and with rifampicin against biofilm-embedded methicillin-resistant S. aureus (MRSA).

METHODS

Two MRSA strains (HUB-4/HUB-5) were evaluated with the Calgary Device System and the dynamic CDC-Biofilm Reactor over 144 h. Dosage regimens simulated the human pharmacokinetics of dalbavancin (1500mg, single dose), vancomycin (1000mg/12 h) and linezolid (600mg/12 h), alone and with rifampicin (600mg/24 h). Efficacy was evaluated by assessing log10 CFU/mL changes (ΔlogCFU/mL) and we screened for resistance.

RESULTS

The minimal biofilm inhibitory/eradication concentrations of dalbavancin were 0.25/16 mg/L (HUB-4) and 0.25/8mg/L (HUB-5), respectively. In the pharmacokinetic/pharmacodynamic analysis, dalbavancin alone showed limited efficacy, but without resistance developing. Adding rifampicin improved the activities of dalbavancin, vancomycin, and linezolid, but rifampicin-resistant strains appeared over time in all cases. Dalbavancin-rifampicin was bactericidal against HUB-4 in the absence of resistance at 72 h and 144 h (ΔlogCFU/mL: -3.54±0.83, -4.32±0.12, respectively), an effect that was only achieved by linezolid-rifampicin at 144h (-3.33 ± 0.66). Against HUB-5, dalbavancin-rifampicin activity was impaired by rifampicin resistance to a greater extent than other combinations and had no bactericidal effect.

CONCLUSIONS

The anti-biofilm efficacy of dalbavancin was improved significantly by adding rifampicin. Although no dalbavancin resistance occurred, rifampicin resistance appeared in all combination therapies and decreased their efficacy over time. Dalbavancin-rifampicin in vitro treatment appears as promising anti-biofilm therapy, but further studies should evaluate the in vivo efficacy and the risk of resistance.

A High Level of Antimicrobial Resistance in Gram-Positive Cocci Isolates from Different Clinical Samples Among Patients Referred to Arsho Advanced Medical Laboratory, Addis Ababa, Ethiopia

Background

Gram-positive cocci are clinically important pathogens that cause infections and their development of antibiotic resistance continues to pose a severe threat to public health. Therefore, this study aims to investigate the level of antimicrobial resistance among Gram-positive cocci isolated from different clinical samples among patients referred to Arsho Advanced Medical Laboratory, Addis Ababa, Ethiopia.

Methods

From January to April 2018, a cross-sectional study was conducted at Arsho Advanced Medical Laboratory. Seven hundred ninety-two (792) different clinical samples were obtained from 792 individuals and inoculated into blood culture bottles and Blood Agar base. Bacterial identification was done using the number, type, and morphology of colonies, as well as Gram staining, catalase testing, and coagulase test after isolation of pure growth on culture media using the standard operating procedure. VITEK 2 compact system was used for bacterial identification and drug susceptibility testing. The information entry and analysis were performed by using SPSS version 20.

Results

Out of 792 clinical samples cultured, the prevalence of Gram-positive cocci was 12.6% (n=100/792). The most frequent one is S. aureus 54% (n=54/100) followed by coagulase-negative Staphylococcus species 42% (n=42/100), S. agalactiae 1% (n=1/100) and E. faecalis 3% (n=3/100). Penicillin showed the highest resistance rate 85% (n=85/100), followed by sulfamethoxazole/trimethoprim (47%), and oxacillin (38%); however, highest sensitivity was seen towards linezolid 97% (n=97/100) and vancomycin 94% (n=94/100). The total multi-drug resistance (MDR) Gram-positive cocci were 44% (n=44/100).

Conclusion

This study demonstrated high antimicrobial resistance and multi-drug resistance. This suggests that the importance of continuous monitoring of antimicrobial resistance patterns is crucial for selecting the suitable drug for treatment and infection prevention.

Comparison of Sequential Dalbavancin to Standard-of-Care Treatment for Staphylococcus aureus Bloodstream Infections

Background

Dalbavancin (DAL) is a long-acting lipoglycopeptide with activity against Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA). This study investigates DAL as sequential therapy in S. aureus bloodstream infections (BSIs).

Methods

We conducted a retrospective cohort study from 2014 to 2021 comparing sequential DAL with standard-of-care therapy (SoC) for S. aureus BSI. The primary outcome was 90-day clinical failure (90-day all-cause mortality or 90-day recurrence). Secondary outcomes were incidence of acute kidney injury, creatinine phosphokinase elevations, catheter-related thrombosis, and hospital-acquired infections. Analyses were adjusted using inverse probability of treatment weighting (IPTW).

Results

Overall, 225 patients (45 DAL, 180 SoC) were included. DAL patients had a higher incidence of community-acquired infection and persons who use drugs; SoC patients had more comorbidities and a longer duration of bacteremia. MRSA incidence was similar between the DAL and SoC groups. The median length of stay was 16 days among DAL recipients compared with 24 days among SoC recipients. Central catheter placement was 17.8% compared with 57.2% in the SoC group. Ninety-day clinical failure occurred in 13.3% and 18.3% of participants in the DAL and SOC groups, respectively. In IPTW-adjusted analysis, sequential DAL was not associated with 90-day clinical failure (adjusted odds ratio, 0.94; 95% CI, 0.333–2.32).

Conclusions

This study provides preliminary evidence that select patients with S. aureus BSI treated with sequential DAL have similar clinical failure rates, with significant reductions in catheter placement and hospital length of stay compared with SoC. Further prospective evaluation is needed.

Investigation of Morchella esculenta and Morchella conica for their antibacterial potential against methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and Streptococcus pyogenes

Antimicrobial resistance is an alarming problem, especially due to emergence of methicillin-resistance Staphylococcus aureus (MRSA). World Health Organization (WHO) has already listed MRSA as a top priority pathogen for the development of novel antibacterial agents. Presently, different therapeutic approaches against bacterial infections are in practice which includes targeting bacterial virulence factors, bacteriophage therapy, and manipulation of the microbiome. Natural products have been efficiently used for centuries to combat bacterial infections. Morchella is a natural fungal product which has been reported to possess broad-spectrum biological activities against bacterial infections. Hence, this study was aimed to evaluate the antibacterial efficacy of two macro-fungi against S. aureus, MRSA, and Streptococcus pyogenes (S. pyogenes). The antibacterial potential of both fungal extracts (Morchella esculenta and Morchella conica) was evaluated using disk diffusion and standard broth microdilution methods. The chemical compounds of both fungi were investigated using ultra-performance liquid chromatography mass spectroscopy (UPLC-MS) analysis. All fungal extracts inhibited growth of tested bacteria with inhibitory zone ranging from 10.66 ± 0.3 to 21.00 ± 1.5 mm. The minimum inhibitory concentration (MIC) of tested bacterial growth ranged from 03.33 to 16.0 mg/ml. It was noteworthy that Morchella extracts prevented S. aureus growth in a bactericidal manner with minimal bactericidal concentration (MBC) of 8-16 mg/ml. The extracts were also more effective against MRSA than currently available antibiotics. In conclusion, the growth inhibition of tested bacteria by fungal extracts revealed their potential as antibacterial agents and their compounds may be used as drug candidates.

Antimicrobial activity of dalbavancin against Gram-positive bacteria isolated from patients hospitalized with bloodstream infection in United States and European medical centers (2018-2020)

Dalbavancin and comparators were susceptibility tested against 8643 Gram-positive bacteria from 74 hospitals located in Europe and the United States by broth microdilution method. The most common organisms were Staphylococcus aureus (45.2%), Enterococcus faecalis (12.2%), and Staphylococcus epidermidis (8.9%), but rank order varied markedly by geographic region. Dalbavancin demonstrated potent activity and broad spectrum, with MIC₉₀ values of 0.03 mg/L for Staphylococcus aureus, β-haemolytic streptococci, and viridans group streptococci; 0.06 mg/L for Enterococcus faecalis and Staphylococcus epidermidis; and 0.12 mg/L for vancomycin-susceptible Enterococcus faecium. All organisms, except vancomycin-resistant enterococci and 1 Staphylococcus haemolyticus isolate, were inhibited at ≤ 0.25 mg/L of dalbavancin.

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.

A Multicentre, Prospective, and Retrospective Registry to Characterize the Use, Effectiveness, and Safety of Dalbavancin in German Clinical Practice

The antibiotic dalbavancin is approved for intravenous treatment of adults with acute bacterial skin and skin structure infections. This study aimed to observe the use, effectiveness, and safety of dalbavancin in clinical practice in Germany. It was a multicentre, prospective, and retrospective registry and consecutively enrolled patients treated with dalbavancin. Each patient was observed from the first to the last dose of dalbavancin, with a 30-day follow-up. Patient inclusion was planned for 2 years, but was terminated early due to low recruitment. All analyses were descriptive. Between November 2018 and December 2019, nine patients were enrolled. Only three patients were treated for the approved indication. Outcome was assessed by the physicians as ‘success’ in five (55.6%) patients, ‘failure’ in one (11.1%) patient, and non-evaluable in three (33.3%) patients. Although the success rate of dalbavancin was lower than reported previously, this may be due to the severity of underlying infections and patients’ high Charlson Comorbidity Index. None of the two reported adverse events were considered related to dalbavancin. These findings were in line with real-world data for dalbavancin from other countries, supporting the drug’s positive benefit–risk profile and suggesting frequent off-label use in German routine practice.

Glycopeptide resistance in Enterococcus spp. and coagulase-negative staphylococci from hospitalized patients in Germany: occurrence, characteristics, and susceptibility to dalbavancin

OBJECTIVE

To evaluate the occurrence of glycopeptide resistance in enterococci and coagulase-negative staphylococci (CoNS), and to determine the susceptibilities of the identified glycopeptide-resistant isolates to dalbavancin.

METHODS

Twenty-two medical laboratories participated in the study conducted in 2016/17 by the Paul-Ehrlich-Society for Chemotherapy. Each laboratory was asked to collect 30 Enterococcus spp. (limited to faecalis/faecium) and 30 CoNS isolates consecutively from hospitalized patients who had a proven or suspected infection.

RESULTS

A total of 1285 isolates were collected, comprising 364 E. faecalis, 291 E. faecium and 630 CoNS. No Enterococcus faecalis isolate but 76 (26.1%) E. faecium isolates were vancomycin-resistant, of which 21 showed the VanA-type and 55 the VanB-type. The proportion of vancomycin-resistant strains among E. faecium isolates from patients in intensive care units (21.6%) was significantly lower than that from patients on regular wards (30.5%). Among the CoNS, 67 (10.6%) isolates were teicoplanin-resistant, but none were vancomycin-resistant, with resistance merely detected in Staphylococcus epidermidis (12.2%), S. haemolyticus (17.9%) and S. hominis (13.2%). Dalbavancin at ≤ 0.25 mg/l inhibited all VanB-type enterococci and 95.5% teicoplanin-resistant CoNS.

CONCLUSIONS

The level of glycopeptide resistance in E. faecalis remains very low in Germany but achieved 26% in E. faecium and was > 10% in CoNS. Dalbavancin seems to be a feasible option for treating infections caused by VanB-type vancomycin-resistant E. faecium and teicoplanin-resistant CoNS.

Clinical Pharmacokinetics and Pharmacodynamics of Dalbavancin

Dalbavancin is a synthetic lipoglycopeptide that exerts its antimicrobial activity through two distinct modes of action, inhibition of cell wall synthesis and an anchoring mechanism. Compared with previous glycopeptide antibiotics, dalbavancin demonstrates improved antibacterial potency against Gram-positive organisms and a long half-life of approximately 1 week, which is longer in tissues (e.g., skin, bone) than plasma. These factors facilitated the development of single-dose or once-weekly dosing regimens to treat acute bacterial skin and skin structure infections (ABSSSI). Dalbavancin exhibits dose-proportional pharmacokinetics and is highly protein bound (93%). Despite being highly protein bound, it has a steady-state volume of distribution >10 L and distributes widely into the skin, bone, peritoneal space, and epithelial lining fluid, but not cerebrospinal fluid. Dalbavancin elimination occurs via a combination of renal (approximately 45%) and non-renal clearance, with dose adjustments recommended only in patients with a creatinine clearance <30 mL/min not receiving any form of dialysis. The established pharmacokinetic/pharmacodynamic index associated with bacterial kill is free area under the concentration-time curve over the minimum inhibitory concentration (fAUC/MIC), with a goal 24-h fAUC/MIC of at least 27.1 for Staphylococcus aureus infections. Recent data suggest usefulness in the treatment of infections beyond ABSSSI, with convenient dosing and redosing strategies for complicated infections requiring extended treatment durations. Additional studies are needed to confirm these preliminary findings.

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.

Evaluation of intraosteoblastic activity of dalbavancin against Staphylococcus aureus in an ex vivo model of bone cell infection

OBJECTIVES

Long-acting lipoglycopeptides are promising therapeutic options in Staphylococcus aureus bone and joint infections (BJIs). This study evaluated the ability of dalbavancin to eradicate the intraosteoblastic reservoir of S. aureus, associated with BJI chronicity.

METHODS

Osteoblastic cells were infected with a standardized inoculum of the S. aureus reference strain HG001 and incubated for 24 h with dalbavancin, vancomycin or rifampicin using the MIC, 10×MIC, 100×MIC and/or the intraosseous concentrations reached using standard therapeutic doses (i.e. vancomycin, 10 mg/L; rifampicin, 2 mg/L; and dalbavancin, 6 mg/L). The remaining intracellular bacteria were quantified by plating cell lysates.

RESULTS

MICs of dalbavancin, vancomycin and rifampicin were 0.125, 1 and 0.004 mg/L, respectively. Dalbavancin significantly reduced the intracellular inoculum of S. aureus starting at a concentration equal to the MIC, with a significant dose effect, ranging from a reduction of 31.4% (95% CI = 17.6%-45.2%) at MIC to 51.6% (95% CI = 39.8%-63.4%) at 100×MIC compared with untreated cells. Of note, dalbavancin was the only molecule to significantly reduce the intraosteoblastic inoculum at low concentration (MIC). At intraosseous concentrations, dalbavancin reduced the intracellular inoculum by 49.6% (95% CI = 45.1%-54.1%) compared with untreated cells (P < 0.001), with no significant difference compared with vancomycin (38.1%; 95% CI = 19.2%-57.0%; P = 0.646), and was less efficient than rifampicin (69.0%; 95% CI = 63.2-74.8; P < 0.001).

CONCLUSIONS

Dalbavancin was able to decrease the intraosteoblastic S. aureus inoculum by 50% at intraosseous concentrations reached during standard human therapeutic dosing, with no difference compared with vancomycin, and remained less efficient than rifampicin. However, it was the only molecule significantly active at low concentration.

Clinical efficacy and safety of novel lipoglycopeptides in the treatment of acute bacterial skin and skin structure infections: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

This systematic review and meta-analysis aimed to investigate the clinical efficacy and safety of novel lipoglycopeptides in treating acute bacterial skin and skin structure infections (ABSSSIs).

RESEARCH DESIGN AND METHODS

PubMed, Embase, Cochrane Central Register of Controlled Trials, Turning Research into Practice, and ClinicalTrials.gov were searched from inception to 20 May 2021. Randomized controlled trials (RCTs) comparing the clinical efficacy and safety of lipoglycopeptides with other comparators in treating adult patients with ABSSSIs were included. The primary outcome was clinical response.

RESULTS

Eight RCTs (6416 patients; lipoglycopeptides: 3359, comparators: 3057) were enrolled. Clinical response rate was not significantly different between lipoglycopeptides and comparators at early-clinical-evaluation (odds ratio [95% confidence interval]: 1.01 [0.85-1.20], I² = 34%), end-of-treatment (0.94 [0.80-1.11], I² = 0%), and test-of-cure (1.05 [0.85-1.30], I² = 0%). Lipoglycopeptides showed a similar overall microbiological eradication rate (1.12 [0.90-1.38], I² = 21%) but a borderline higher microbiological eradication rate for methicillin-resistant Staphylococcus aureus (1.37 [1.00-1.86], I² = 0%) than the comparators. Lipoglycopeptides were not associated with a higher risk than comparators.

CONCLUSIONS

Lipoglycopeptides can achieve similar clinical and microbiological responses to other comparators in treating ABSSSIs. In addition, lipoglycopeptides are as tolerable as their comparators.

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.

Antimicrobial activity of dalbavancin and comparators against Staphylococcus aureus causing pneumonia in patients with and without cystic fibrosis

The activities of dalbavancin and comparator agents were evaluated against Staphylococcus aureus isolated from the lower respiratory tract of cystic fibrosis (CF) and non-CF patients with pneumonia. Bacterial isolates (n = 357) were collected from CF patients in 36 medical centers worldwide (2018-2019) and susceptibility tested using reference broth microdilution. Susceptibility results from these isolates were compared with those for 725 S. aureus isolates consecutively collected from non-CF patients with pneumonia from the same medical centers over the same period. Only isolates determined to be the probable cause of pneumonia were included in the study. Susceptibility profiles were very similar among isolates from CF and non-CF patients. Dalbavancin exhibited potent activity (MIC50/90, 0.03/0.03 mg/L) and complete coverage (100.0% susceptibility) against isolates from CF and non-CF patients. Ceftaroline (MIC50/90, 0.25/1 mg/L) was active against 97.8% and 98.1% of isolates from CF and non-CF patients, respectively. Oxacillin resistance (MRSA) rates were 27.7% among CF and 28.7% among non-CF patients. Among MRSA isolates from CF/non-CF patients (n = 99/208), susceptibility to ceftaroline, clindamycin, levofloxacin, and tetracycline were 91.9%/93.3%, 58.6%/64.4%, 40.4%/29.3%, and 83.8%/89.4%, respectively. Dalbavancin demonstrated high potency against S. aureus from CF and non-CF patients and may represent a valuable treatment option for CF patients with MRSA pulmonary infection.

Update on Coagulase-Negative Staphylococci-What the Clinician Should Know

Coagulase-negative staphylococci (CoNS) are among the most frequently recovered bacteria in routine clinical care. Their incidence has steadily increased over the past decades in parallel to the advancement in medicine, especially in regard to the utilization of foreign body devices. Many new species have been described within the past years, while clinical information to most of those species is still sparse. In addition, interspecies differences that render some species more virulent than others have to be taken into account. The distinct populations in which CoNS infections play a prominent role are preterm neonates, patients with implanted medical devices, immunodeficient patients, and those with other relevant comorbidities. Due to the property of CoNS to colonize the human skin, contamination of blood cultures or other samples occurs frequently. Hence, the main diagnostic hurdle is to correctly identify the cases in which CoNS are causative agents rather than contaminants. However, neither phenotypic nor genetic tools have been able to provide a satisfying solution to this problem. Another dilemma of CoNS in clinical practice pertains to their extensive antimicrobial resistance profile, especially in healthcare settings. Therefore, true infections caused by CoNS most often necessitate the use of second-line antimicrobial drugs.

Long-Acting Lipoglycopeptides for the Treatment of Bone and Joint Infections

Background: The long-acting lipoglycopeptides dalbavancin and oritavancin possess excellent microbiologic activity against gram-positive bacteria and provide prolonged tissue exposure at sites of infection. Moreover, these antibiotics are well tolerated and do not require therapeutic drug monitoring. Methods: Pharmacokinetic/pharmacodynamic experiments ascertained that one to two doses of these long-acting agents can provide an extended period (≥6 weeks) of antimicrobial therapy. Results: Clinical studies subsequently found that microbiologic and clinical response rates with these agents were comparable to standard antibiotic agents used in the treatment of bone and joint infections. In addition, pharmacoeconomic analyses have discovered cost savings with the use of these antimicrobial agents in the treatment of serious deep-seated bacterial infections. Conclusions: Thus, these long-acting lipoglycopeptides offer potential for cost-effective outpatient parenteral antibiotic therapy of difficult to treat infections, such as osteomyelitis.

Safety of Dalbavancin in the Treatment of Acute Bacterial Skin and Skin Structure Infections (ABSSSI): Nephrotoxicity Rates Compared with Vancomycin: A Post Hoc Analysis of Three Clinical Trials

Introduction

Dalbavancin is a lipoglycopeptide antibiotic approved as a single- and two-dose regimen for adults with acute bacterial skin and skin structure infections (ABSSSI) caused by susceptible gram-positive organisms. We present nephrotoxicity rates for patients with ABSSSI who received dalbavancin in three pivotal clinical trials and compare the rates with vancomycin.

Methods

In a phase 3b clinical trial (DUR001-303), patients were randomized to dalbavancin single-dose (1500 mg intravenous [IV]) or two-dose regimen (1000 mg IV on day 1, 500 mg IV on day 8). In two phase 3 clinical trials (DISCOVER 1 and DISCOVER 2), patients were randomized to dalbavancin (two-dose regimen) or vancomycin 1 g (or 15 mg/kg) IV every 12 h for at least 3 days with an option to switch to orally administered linezolid 600 mg every 12 h for 10–14 days. Patients on dalbavancin with a creatinine clearance below 30 mL/min not on regular dialysis received a reduced dose of 1000 mg (single-dose arm) or 750 mg IV on day 1, 375 mg IV on day 8 (two-dose arm). Nephrotoxicity was defined as a 50% increase from baseline serum creatinine (SCr) or an absolute increase in SCr of 0.5 mg/dL at any time point. P values were obtained using the Cochran–Mantel–Haenszel test.

Results

In dalbavancin-treated patients, rates of nephrotoxicity were low. The safety population with available creatinine values included 1325/1347 patients on any regimen of dalbavancin, and 54/651 patients who received vancomycin intravenously for at least 10 days and were not switched to orally administered linezolid. Patients on any regimen of dalbavancin had a lower rate of nephrotoxicity compared with patients receiving vancomycin intravenously for at least 10 days (3.7% vs 9.3%, respectively; P = 0.039).

Conclusions

Nephrotoxicity rates were lower in patients on dalbavancin relative to vancomycin for at least 10 days. On the basis of this experience, dalbavancin may be less nephrotoxic than intravenously administered vancomycin.

Simultaneous Quantification and Pharmacokinetic Study of Five Homologs of Dalbavancin in Rat Plasma Using UHPLC-MS/MS

Dalbavancin is a novel semisynthetic glycopeptide antibiotic that comprises multiple homologs and isomers of similar polarities. However, pharmacokinetic studies have only analyzed the primary components of dalbavancin, namely B₀ and B₁. In this study, an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed to simultaneously determinate and investigate the five homologous components of dalbavancin, namely, A₀, A₁, B₀, B₁, and B₂, in rat plasma. In this method, methanol was used to precipitate plasma, and a triple-bonded alkyl chromatographic column was used for molecule separation, using 0.1% formic acid-acetonitrile as the mobile phase for gradient elution. Targeted homologs were analyzed by a triple quadrupole mass spectrometer using positive electrospray ionization in multiple reaction monitoring mode. The linearity range was 50–2500 ng/mL with a high correlation coefficient (r² > 0.998). This method was successfully applied in the pharmacokinetic analysis of dalbavancin hydrochloride to investigate dalbavancin components in rats.

Update on the in vitro activity of dalbavancin against indicated species (Staphylococcus aureus, Enterococcus faecalis, β-hemolytic streptococci, and Streptococcus anginosus group) collected from United States hospitals in 2017-2019

This study updates dalbavancin activity against contemporary (2017-2019) isolates of indicated species/groups (n = 16,451). Isolates from 71 hospitals were tested by broth microdilution method. All isolates were susceptible to dalbavancin. Dalbavancin MIC_50/90 values remained stable for Staphylococcus aureus, vancomycin-susceptible Enterococcus faecalis, β-hemolytic streptococci, and Streptococcus anginosus group since its clinical approval.

On- and off-label utilization of dalbavancin and oritavancin for Gram-positive infections

BACKGROUND

Long-acting lipoglycopeptides (laLGPs) are FDA approved only for acute bacterial skin and skin structure infections (ABSSSIs). However, these antibiotics show promise for off-label use, reductions in hospital length of stay (LOS) and healthcare cost savings.

OBJECTIVES

To assess the effectiveness, safety, impact on LOS and estimated cost savings from laLGP treatment for Gram-positive infections.

METHODS

Retrospective cohort of adult patients who received at least one dose of laLGPs at the University of Colorado Health system. Descriptive statistics were utilized for analysis.

RESULTS

Of 59 patients screened, 56 were included: mean age 47 years, 59% male and 30% injection drug users/polysubstance abusers (dalbavancin, 71%; oritavancin, 25%; both, 4%). Most common indications for laLGP: ABSSSIs (36%), osteomyelitis (27%) and endocarditis (9%). Most common isolated pathogens: MSSA and MRSA (25% and 19%, respectively), Enterococcus faecalis (11%) and CoNS (11%). Previous antibiotics were administered for a median of 13 days (IQR = 7.0-24.5 days) and laLGPs for a median of one dose (IQR = 1-2 doses). Ten (18%) patients were lost to follow-up. Clinical failure was found in 7/47 (15%) cases with adequate follow-up. Mild adverse effects occurred in six (11%) patients. Projected reduction in hospital LOS and health-system costs were 514 days (9.18 days/person average) and $963456.72 ($17204.58/person average), respectively.

CONCLUSIONS

Prospective trials are needed to validate the use of these antibiotics for Gram-positive infections in practice, with the hope that they will reduce hospital LOS and the need for daily antibiotic infusions to provide alternative options for patients not qualifying for outpatient parenteral antimicrobial therapy.

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.

Novel strategies for the management of bacterial and fungal infections in patients with liver cirrhosis: focus on new antimicrobials

Introduction: Liver cirrhosis is a frequent condition caused by different etiologies. Bacterial and fungal infections are common complications, representing an independent prognostic stage in patients with cirrhosis, dramatically worsening their clinical outcomes.Areas covered: The present review article addresses manifold points and to this purpose an inductive literature search of MEDLINE database through PubMed was performed. First, it provides an overview on the mechanisms underlying immune disfunctions in patients with cirrhosis, who are prone to develop infections being at higher risk than the general population. Second, commonest types of bacterial and fungal infections in patients with advanced liver disease are described, focusing on their deleterious impact as decompensating events. Third, the rise of multidrug-resistant (MDR) bacteria and fungi as causative agents of infection in cirrhotic subjects is illustrated. Eventually, the most promising novel therapeutic options against MDR pathogens and fungi are reviewed.Expert opinion: The management of bacterial and fungal infections in patients with cirrhosis is difficult, due to the frequent co-existence of renal impairment, low platelet count and other conditions that limit the antimicrobial choice. New antibacterial and antifungal compounds may overcome this issue by providing a better tolerability profile, along with equal or superior efficacy compared with older drugs.

Left Ventricular Assist Device Infections and the Potential Role for Dalbavancin: A Case Report

Left ventricular assist device infections (LVADIs) are common but challenging to treat, often requiring prolonged courses of intravenous antibiotics. Dalbavancin could have a role in treating patients with chronic LVADIs given its less frequent dosing requirements. Here, we illustrate a case in which dalbavancin was used as suppressive therapy for an LVADI for greater than 7 months.

In vitro activity of Exebacase (CF-301) against clinical Staphylococcus aureus surveillance isolates from the United States, Europe, and Latin America, 2015-2017

Lysins are direct lytic agents which act through enzymatic cell-wall-hydrolysis and represent a potential new class of antimicrobial agents in development to treat antibiotic-resistant bacterial infections. Exebacase (CF-301) is a first-in-class lysin now in clinical development for the treatment of Staphylococcus aureus (S. aureus) bacteremia and infective endocarditis (IE) when used in addition to conventional antibiotics. Exebacase and comparator antibiotics were tested by broth microdilution against a set of 535 clinical MSSA and MRSA isolates collected from 2015 to 2017 throughout the United States, Europe and South America. All S. aureus isolates were inhibited by ≤1 mg/L exebacase (MIC_50/90, 0.5/1 mg/L) with a range of 0.25-1 mg/L. No difference in susceptibility was observed between the MSSA and MRSA isolates. Exebacase was uniformly and equivalently active against all recent clinical MSSA and MRSA surveillance isolates from a broad survey across 3 continents.

Antimicrobial Resistance Surveillance and New Drug Development

Surveillance represents an important informational tool for planning actions to monitor emerging antimicrobial resistance. Antimicrobial resistance surveillance (ARS) programs may have many different designs and can be grouped in 2 major categories based on their main objectives: (1) public health ARS programs and (2) industry-sponsored/product-oriented ARS programs. In general, public health ARS programs predominantly focus on health care and infection control, whereas industry ARS programs focus on an investigational or recently approved molecule(s). We reviewed the main characteristics of industry ARS programs and how these programs contribute to new drug development. Industry ARS programs are generally performed to comply with requirements from regulatory agencies responsible for commercial approval of antimicrobial agents, such as the US Food and Drug Administration, European Medicines Agency, and others. In contrast to public health ARS programs, which typically collect health care and diverse clinical data, industry ARS programs frequently collect the pathogens and perform the testing in a central laboratory setting. Global ARS programs with centralized testing play an important role in new antibacterial and antifungal drug development by providing information on the emergence and dissemination of resistant organisms, clones, and resistance determinants. Organisms collected by large ARS programs are extremely valuable to evaluate the potential of new agents and to calibrate susceptibility tests once a drug is approved for clinical use. These programs also can provide early evaluations of spectrum of activity and postmarketing trends required by regulatory agencies, and the programs may help drug companies to select appropriate dosing regimens and the appropriate geographic regions in which to perform clinical trials. Furthermore, these surveillance programs provide useful information on the potency and spectrum of new antimicrobial agents against indications and organisms in which clinicians have little or no experience. In summary, large ARS programs, such as the SENTRY Antimicrobial Surveillance Program, contribute key data for new drug development.

Toward Single-Peak Dalbavancin Analogs through Biology and Chemistry

Glycopeptide antibiotics are used to treat severe multidrug resistant infections caused by Gram-positive bacteria. Dalbavancin is a second generation glycopeptide approved for human use, which is obtained from A40926, a lipoglycopeptide produced by Nonomuraea sp. ATCC39727 as a mixture of biologically active congeners mainly differing in the fatty acid chains present on the glucuronic moiety. In this study, we constructed a double mutant of the A40926 producer strain lacking dbv23, and thus defective in mannose acetylation, a feature that increases A40926 production, and lacking the acyltransferases Dbv8, and thus incapable of installing the fatty acid chains. The double mutant afforded the desired deacyl, deacetyl A40926 intermediates, which could be converted by chemical reacylation yielding A40926 analogs with a greatly reduced number of congeners. The newly acylated analogs could then be transformed into dalbavancin analogs possessing the same in vitro properties as the approved drug.