Biofilm-Related Infections in Gram-Positive Bacteria and the Potential Role of the Long-Acting Agent Dalbavancin

Biofilm Biology to Brain Health: Harnessing Microbial Wisdom to Uncover Amyloid Dissociating Bifunctional Nano Chaperones for Alzheimer's Therapeutics

Microbial infections have long been implicated in the gut-brain link to Alzheimer's disease (AD). These infections may influence AD development either directly, through brain invasion, or indirectly via bacterial metabolites crossing the blood-brain-barrier (BBB) or interacting with the enteric nervous system (ENS). Such findings have inspired clinicians to repurpose antimicrobial drugs for AD, yielding promising results. However, the sole bacterial link to AD may be insufficiently understood. Bacterial amyloid presence in biofilms is well-documented, with certain bacterial proteins exacerbating amyloid formation while others inhibit it. For instance, Curli-specific gene protein C (CsgC) in E. coli suppresses curli amyloid formation. This review investigates the possibility of human CsgC-like proteins, identifying beta-2 microglobulin (β2M) and E3 ubiquitin ligases (E3s) as potential analogs that may influence amyloid degradation. We propose that nanoparticles (NPs) could serve as platforms to anchor these proteins, forming Amyloid Dissociating Bifunctional NanoChaperones (ADBiNaCs) with enhanced antiamyloidogenic activity. This innovative approach holds promise for novel AD treatment strategies, meriting further investigation into the role of bacterial and human amyloid-modulating proteins in AD pathology.

Antimicrobial and Antibiofilm Activity of Auranofin and Its Two Derivatives Bearing Naproxen and Acetylcysteine as Ligands Against Staphylococci

Background/Objectives: The ability of bacteria to form biofilms makes them more tolerant to traditional antibiotics. Given the lack of new antibiotic development, drug repurposing offers a strategy for discovering new treatments. Auranofin (AF), a gold-based compound indicated for the treatment of rheumatoid arthritis, shows promising antibacterial activity. This study investigates the antimicrobial and antibiofilm activity of AF and its two derivatives in which the thiosugar ligand is replaced by acetylcysteine (AF-AcCys) or naproxen (AF-Napx), against Staphylococcus aureus and Staphylococcus epidermidis. Methods: AF was conjugated by transmetalation with either naproxen or acetylcysteine. Assessments of their stability in DMSO/H2O and lipophilicity expressed as the LogP were performed. The antimicrobial activity of AF and its analogues were investigated by broth microdilution assay to determine the minimum inhibitory concentration (MIC) and versus biofilm to obtain the minimum bactericidal biofilm concentration (MBBC) and minimum biofilm eradication concentration (MBEC). Results: AF derivatives were found to be stable in a DMSO/H2O mixture for 48 h. AF-Napx showed a LogP = 1.25 ± 0.22, close to AF, while AF-AcCys had a LogP = -0.95. MIC values of S. aureus and S. epidermidis were ranging from 2 µM to 0.25 µM, and ≤0.12 µM, respectively. Both AF and AF-Napx maintained efficacy against biofilm-embedded S. aureus and S. epidermidis at non-cytotoxic concentrations, with AF-Napx demonstrating lower MBBC values for S. epidermidis. Conclusions: AF, and especially its naproxen conjugate, holds potential as a therapeutic agent for treating biofilm-associated infections caused by S. aureus and S. epidermidis, particularly in device-related infections where both infection and inflammation are present.

Biofilm-mediated antibiotic tolerance in Staphylococcus aureus from spinal cord stimulation device-related infections

Staphylococcus aureus is a predominant cause of infections in individuals with spinal cord stimulation (SCS) devices. Biofilm formation complicates these infections, commonly requiring both surgical and antibiotic treatments. This study explored the biofilm matrix composition and antimicrobial susceptibility of planktonic and biofilm-growing S. aureus isolates from individuals with SCS-related infections. Whole-genome sequencing (WGS) examined genotypes, virulome, resistome, and the pan-genome structure. The study also analyzed biofilm matrix composition, early surface adhesion, hemolytic activity, and antibiotic-susceptibility testing. WGS revealed genetic diversity among isolates. One isolate, though oxacillin susceptible, contained the mecA gene. The median number of virulence factor genes per isolate was 58. All isolates harbored the biofilm-related icaA/D genes. When assessing phenotypic characteristics, all strains demonstrated the ability to form biofilms in vitro. The antimicrobial susceptibility profile indicated that oxacillin, rifampin, and teicoplanin showed the highest efficacy against S. aureus biofilm. Conversely, high biofilm tolerance was observed for vancomycin, trimethoprim/sulfamethoxazole, and levofloxacin. These findings suggest that S. aureus isolates are highly virulent and produce robust biofilms. In cases of suspected biofilm infections caused by S. aureus, vancomycin should not be the primary choice due to its low activity against biofilm. Instead, oxacillin, rifampin, and teicoplanin appear to be more effective options to manage SCS infections.IMPORTANCESCS devices are increasingly used to manage chronic pain, but infections associated with these devices, particularly those caused by Staphylococcus aureus, present significant clinical challenges. These infections are often complicated by biofilm formation, which protects bacteria from immune responses and antibiotic treatments, making them difficult to eradicate. Understanding the genetic diversity, virulence, and biofilm characteristics of S. aureus isolates from SCS infections is critical to improving treatment strategies. Our study highlights the need to reconsider commonly used antibiotics like vancomycin, which shows reduced activity against biofilm-growing cells. Identifying more effective alternatives, such as oxacillin, rifampin, and teicoplanin, provides valuable insight for clinicians when managing biofilm-related S. aureus infections in patients with SCS implants. This research contributes to the growing evidence that biofilm formation is crucial in treating device-related infections, emphasizing the importance of tailoring antimicrobial strategies to the biofilm phenotype.

Dalbavancin-resistant Staphylococcus epidermidis in vivo selection following a prosthetic joint infection: phenotypic and genomic characterization

Background

Dalbavancin is a lipoglycopeptide antibiotic with a wide spectrum of activity against Gram-positive bacteria, including MDR isolates. Its pharmacokinetic properties and administration patterns could be useful for the treatment of bone and joint infections, especially prosthetic joint infections (PJIs).

Introduction

We report the case of an 80-year-old man who experienced an acute periprosthetic joint infection of his right total knee arthroplasty (TKA). A DAIR procedure was done with tissue sampling, which allowed identification of a linezolid-resistant MDR S. epidermidis (LR-MDRSE) strain. The patient was then treated with dalbavancin (four injections).

Methods

We studied the phenotypic and genomic evolution of the strains and plasma through concentrations of dalbavancin at different points in time.

Results

After four injections (1500 mg IV) of dalbavancin over a 6 month period, the dalbavancin MIC increased 4-fold. Calculated fAUC0-24/MIC ratios were 945, 1239 and 766.5, respectively, at Days 49, 71 and 106, assuming an MIC of 0.032 mg/L. The PFGE dendrogram revealed 97% similarity among all the isolates. These results suggest acquisition by the S. epidermidis strain of dalbavancin resistance when the patient underwent dalbavancin treatment. A 4-amino-acid deletion in the walK gene coinciding with the emergence of phenotypic resistance was revealed by WGS without any other relevant indels.

Conclusions

Despite dalbavancin treatment with pharmacokinetic management, emerging dalbavancin resistance in S. epidermidis was observed, resulting in treatment failure. This outcome led to a prosthesis revision and long-term suppressive antibiotic therapy, with no recurrence of PJI after an 18 month follow-up.

Population Pharmacokinetics and Pharmacodynamics of Dalbavancin and C-Reactive Protein in Patients with Staphylococcal Osteoarticular Infections

BACKGROUND AND OBJECTIVE

Dalbavancin is increasingly used for the long-term treatment of chronic osteoarticular infections. A population pharmacokinetic/pharmacodynamic (PK/PD) analysis for assessing the relationship between dalbavancin exposure and C-reactive protein (C-RP) over time was conducted.

METHODS

Non-linear mixed-effect modeling was fitted to dalbavancin and C-RP concentrations. Monte Carlo simulations assessed the weekly percentage of C-RP reduction associated with different dosing regimens, starting from baseline to < 1 mg/dL.

RESULTS

A total of 45 patients were retrospectively included in the analysis. The PK of dalbavancin was described by a two-compartment model, and the PD of C-RP was described by an indirect turnover maximum inhibition model. The total dalbavancin concentration model estimate producing 50% of maximum C-RP production inhibition (IC50) was 0.70 mg/L. Monte Carlo simulations showed that in patients with staphylococcal osteoarticular infections targeting total dalbavancin concentrations at > 14.5 mg/L at any time point may achieve C-RP production inhibition over time in > 95% of patients. Based on this, the findings showed that a cumulative dose of 3000 mg administered in the first 3 weeks may lead to a > 90% C-RP decrease versus baseline in approximately 5-6 weeks. In patients needing treatment prolongation, an additional 1500 mg dose after this period may maintain C-RP concentrations < 1 mg/dL for other 3 weeks.

CONCLUSIONS

A decrease in C-RP is related to dalbavancin exposure in osteoarticular infections. Targeting dalbavancin plasma concentrations above the efficacy threshold may be associated with effective treatment.

Efficacy of sodium hypochlorite in overcoming antimicrobial resistance and eradicating biofilms in clinical pathogens from pressure ulcers

Sodium hypochlorite (NaOCl) is widely recognized for its broad-spectrum antimicrobial efficacy in skin wound care. This study investigates the effectiveness of NaOCl against a range of bacterial and fungal isolates from pressure ulcer (PU) patients. We analyzed 20 bacterial isolates from PU patients, comprising carbapenem-resistant Klebsiella pneumoniae (CRKP), multidrug-resistant Acinetobacter baumannii (MDRAB), methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible Staphylococcus aureus (MSSA), along with 5 Candida albicans isolates. Antibiotic resistance profiles were determined using standard susceptibility testing. Whole-genome sequencing (WGS) was employed to identify antimicrobial resistance genes (ARGs) and disinfectant resistance genes (DRGs). Genetic determinants of biofilm formation were also assessed. The antimicrobial activity of NaOCl was evaluated by determining the minimum inhibitory concentration (MIC) and the minimal biofilm eradication concentration (MBEC) for both planktonic and biofilm-associated cells. CRKP and MDRAB showed resistance to fluoroquinolones and carbapenems, while MRSA exhibited resistance to β-lactams and levofloxacin. MSSA displayed a comparatively lower resistance profile. WGS identified significant numbers of ARGs in CRKP and MDRAB, with fewer DRGs compared to MRSA and MSSA. All isolates possessed genes associated with fimbriae production and adhesion, correlating with pronounced biofilm biomass production. NaOCl demonstrated substantial antimicrobial activity against both planktonic cells and biofilms. The MIC90 for planktonic bacterial cells was 0.125 mg/mL, and the MBEC90 ranged from 0.225 to 0.5 mg/mL. For planktonic C. albicans, the MIC90 was 0.150 mg/mL, and the MBEC90 was 0.250 mg/mL. These results highlight the challenge in treating biofilm-associated infections and underscore the potential of NaOCl as a robust antimicrobial agent against difficult-to-treat biofilm infections at concentrations lower than those typically found in commercial disinfectants.

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.

Strontium and Zinc Co-Doped Mesoporous Bioactive Glass Nanoparticles for Potential Use in Bone Tissue Engineering Applications

Mesoporous bioactive glass nanoparticles (MBGNs) have attracted significant attention as multifunctional nanocarriers for various applications in both hard and soft tissue engineering. In this study, multifunctional strontium (Sr)- and zinc (Zn)-containing MBGNs were successfully synthesized via the microemulsion-assisted sol-gel method combined with a cationic surfactant (cetyltrimethylammonium bromide, CTAB). Sr-MBGNs, Zn-MBGNs, and Sr-Zn-MBGNs exhibited spherical shapes in the nanoscale range of 100 ± 20 nm with a mesoporous structure. Sr and Zn were co-substituted in MBGNs (60SiO2-40CaO) to induce osteogenic potential and antibacterial properties without altering their size, morphology, negative surface charge, amorphous nature, mesoporous structure, and pore size. The synthesized MBGNs facilitated bioactivity by promoting the formation of an apatite-like layer on the surface of the particles after immersion in Simulated Body Fluid (SBF). The effect of the particles on the metabolic activity of human mesenchymal stem cells was concentration-dependent. The hMSCs exposed to Sr-MBGNs, Zn-MBGNs, and Sr-Zn-MBGNs at 200 μg/mL enhanced calcium deposition and osteogenic differentiation without osteogenic supplements. Moreover, the cellular uptake and internalization of Sr-MBGNs, Zn-MBGNs, and Sr-Zn-MBGNs in hMSCs were observed. These novel particles, which exhibited multiple functionalities, including promoting bone regeneration, delivering therapeutic ions intracellularly, and inhibiting the growth of Staphylococcus aureus and Escherichia coli, are potential nanocarriers for bone regeneration applications.

Comparison of dalbavancin with standard of care in the management of infective endocarditis: efficacy, safety, and cost analysis

OBJECTIVES

Due to its long half-life, dalbavancin offers benefits for long-duration treatments, especially osteoarticular and infective endocarditis (IE). We evaluated the efficacy and costs of IE treatment, comparing dalbavancin with standard of care (SOC).

METHODS

Retrospective multicenter cohort study of adult patients with Gram-positive cocci definite IE. Dalbavancin was used as a sequential therapy before discharge. Efficacy was a combined variable of clinical cure and absence of recurrence in 12-month follow-up. Length of hospital stay and the associated costs were analyzed in both groups of treatment.

RESULTS

Twenty-two patients received dalbavancin and 47 SOC. The efficacy was similar between the groups (dalbavancin 18 [72%] vs SOC 44 [94%], P = 0.198). Hospital stay was shorter in the dalbavancin group (dalbavancin 22 days [16-34] vs SOC 37 days [23-49], P = 0.001), especially in those with E. faecalis IE (dalbavancin 30 days [20-36] vs SOC 65 days [46-74], P <0.001). A reduction of cost was observed between both groups (dalbavancin, 12,206 € [8998-17,283] vs SOC 16,249 € [11,496-22,367], P = 0.032).

CONCLUSION

Dalbavancin could be a safe and effective option in the sequential treatment of patients with IE. Also, a cost reduction was detected, due to a significant shortness of hospital stay.

Usefulness of dalbavancin in early discharge and nonhospitalization. It's time to throw your heart over the obstacle?

Introduction

Dalbavancin is a semisynthetic lipoglycopeptide long-acting antibiotic approved for the treatment of acute bacterial skin and skin structure infections (ABSSSIs). Its features can be useful in the current healthcare scenario characterized by the shortage of available hospital beds.

Materials methods and results

We implemented several actions in order to optimize the use of dalbavancin allowing an improvement strategy both from the healthcare system and the patient's perspective in two hospital settings. In the Emergency Department we hospitalized only patients who met the clinical criteria and not the logistic criteria (i.e., the need for antibiotic therapy infusion). During the years 2017-2023, this strategy was applied in 40 cases, thus avoiding 40 hospitalizations for a total saving of 280 days of hospitalization.In the Internal Medicine ward and surgery department when there was no longer any need for hospitalization, we discharged the patient as early as possible. During the years 2017-2023, this strategy was applied in 189 cases, saving at least 1,134 days of hospitalization. The outcome of the treated patients was favorable in 228 out of 229 patients (99.5%).

Conclusions

Our experience using dalbavancin in ABSSSI has been very satisfactory overall. The efficacy was close to 100%. Minor adverse events of slight severity occurred rarely. At the same time, this strategy allowed a more efficient allocation of hospital beds. Dalbavancin presents an ideal pharmacodynamic/pharmacokinetic profile for the management of ABSSSI especially in settings where shortage of hospital beds is critical.

Development and challenges of antimicrobial peptide delivery strategies in bacterial therapy: A review

The escalating global prevalence of antimicrobial resistance poses a critical threat, prompting concerns about its impact on public health. This predicament is exacerbated by the acute shortage of novel antimicrobial agents, a scarcity attributed to the rapid surge in bacterial resistance. This review delves into the realm of antimicrobial peptides, a diverse class of compounds ubiquitously present in plants and animals across various natural organisms. Renowned for their intrinsic antibacterial activity, these peptides provide a promising avenue to tackle the intricate challenge of bacterial resistance. However, the clinical utility of peptide-based drugs is hindered by limited bioavailability and susceptibility to rapid degradation, constraining efforts to enhance the efficacy of bacterial infection treatments. The emergence of nanocarriers marks a transformative approach poised to revolutionize peptide delivery strategies. This review elucidates a promising framework involving nanocarriers within the realm of antimicrobial peptides. This paradigm enables meticulous and controlled peptide release at infection sites by detecting dynamic shifts in microenvironmental factors, including pH, ROS, GSH, and reactive enzymes. Furthermore, a glimpse into the future reveals the potential of targeted delivery mechanisms, harnessing inflammatory responses and intricate signaling pathways, including adenosine triphosphate, macrophage receptors, and pathogenic nucleic acid entities. This approach holds promise in fortifying immunity, thereby amplifying the potency of peptide-based treatments. In summary, this review spotlights peptide nanosystems as prospective solutions for combating bacterial infections. By bridging antimicrobial peptides with advanced nanomedicine, a new therapeutic era emerges, poised to confront the formidable challenge of antimicrobial resistance head-on.

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.

Advancing biofilm management through nanoformulation strategies: a review of dosage forms and administration routes

Biofilms are complex microbial communities formed by the attachment of bacteria or fungi to surfaces encased in a self-produced polymeric matrix. These biofilms are highly resistant to conventional antimicrobial therapies. The resistance mechanisms exhibited by biofilms include low antibiotic absorption, sluggish replication, adaptive stress response, and the formation of dormant-like phenotypes. The eradication of biofilms requires alternative strategies and approaches. Nanotechnological drug delivery systems allow excellent control over the drug chemistry, surface area, particle size, particle shape, and composition of nanostructures. Nanoformulations can enhance the efficacy of antimicrobial agents by improving their bioavailability, stability, and targeted delivery to the site of infection that helps biofilm eradication more effectively. In addition to nanoformulations, the route of administration and choice of dosage forms play a crucial role in treating biofilm infections. Systemic administration of antibiotics is effective in controlling systemic infection and sepsis associated with biofilms. Alternative routes of administration, such as inhalation, vaginal, ocular, or dermal, have been explored to target biofilm infections in specific organs. This review primarily examines the utilisation of nanoformulations in various administration routes for biofilm management. It also provides an overview of biofilms, current approaches, and the drawbacks associated with conventional methods.

In Vitro Efficacy of Dalbavancin as a Long-Acting Anti-Biofilm Agent Loaded in Bone Cement

Based on previous studies by our group in which we demonstrated that dalbavancin loaded in bone cement had good elution capacity for the treatment of biofilm-related periprosthetic infections, we now assess the anti-biofilm activity of dalbavancin and compare it with that of vancomycin over a 3-month period. We designed an in vitro model in which we calculated the percentage reduction in log cfu/mL counts of sonicated steel discs contaminated with staphylococci and further exposed to bone cement discs loaded with 2.5% or 5% vancomycin and dalbavancin at various timepoints (24 h, 48 h, 1 week, 2 weeks, 6 weeks, and 3 months). In addition, we tested the anti-biofilm activity of eluted vancomycin and dalbavancin at each timepoint based on a 96-well plate model in which we assessed the percentage reduction in metabolic activity. We observed a significant decrease in the dalbavancin concentration from 2 weeks of incubation, with sustained anti-biofilm activity up to 3 months. In the case of vancomycin, we observed a significant decrease at 1 week. The concentration gradually increased, leading to significantly lower anti-biofilm activity. The percentage reduction in cfu/mL counts was higher for dalbavancin than for vancomycin at both the 2.5% and the 5% concentrations. The reduction in log cfu/mL counts was higher for S. epidermidis than for S. aureus and was particularly more notable for 5% dalbavancin at 3 months. In addition, the percentage reduction in metabolic activity also decreased at 3 months in 5% dalbavancin and 5% vancomycin, with more notable values recorded for the latter.

Emerging Treatments and the Clinical Trial Landscape for Hidradenitis Suppurativa Part I: Topical and Systemic Medical Therapies

Hidradenitis suppurativa (HS) is an oftentimes debilitating condition that presents with painful nodules, abscesses, and sinus tracts. This condition is challenging to treat, in part because the pathogenesis of the condition is incompletely understood but also because there are limited therapeutic options. HS research is undergoing explosive growth with multiple new molecular pathways under study, which will hopefully lead to improved disease control for patients. Part I of this review will provide an overview of the emerging topical and systemic therapies under investigation for HS.

Invasive Candida infection: epidemiology, clinical and therapeutic aspects of an evolving disease and the role of rezafungin

INTRODUCTION

Invasive Candida Infections (ICIs) have undergone a series of significant epidemiological, pathophysiological, and clinical changes during the last decades, with a shift toward non-albicans species, an increase in the rate of exogenous infections and clinical manifestations ranging from candidemia to an array of highly invasive and life-threatening clinical syndromes. The long-acting echinocandin rezafungin exhibits potent in-vitro activity against most wild-type and azole-resistant Candida spp. including C.auris.

AREAS COVERED

The following topics regarding candidemia only and ICIs were reviewed and addressed: i) pathogenesis; ii) epidemiology and temporal evolution of Candida species; iii) clinical approach; iv) potential role of the novel long-acting rezafungin in the treatment of ICIs.

EXPERT OPINION

Authors' expert opinion focused on considering the potential role of rezafungin in the evolving context of ICIs. Rezafungin, which combines a potent in-vitro activity against Candida species, including azole-resistant strains and C.auris, with a low likelihood of drug-drug interactions and a good safety profile, may revolutionize the treatment of candidemia/ICI. Indeed, it may shorten the length of hospital stays when clinical conditions allow and extend outpatient access to treatment of invasive candidiasis, especially when prolonged treatment duration is expected.

Chronic Suppressive Antibiotic Treatment for Staphylococcal Bone and Joint Implant-Related Infections

Prosthetic joint infection (PJI) and fracture-related infection (FRI) are difficult-to-treat conditions in patients with severe comorbidity or significant surgical risk. In cases not eligible for standard strategy, debridement procedures with the retention of prosthesis or internal fixation device, combined with long-term antibiotic treatment and subsequent indefinite chronic oral antimicrobial suppression (COAS), can be the only reasonable choice. The aim of this study was to investigate the role of COAS and its follow-up in the management of these cases. We retrospectively analyzed a cohort of 16 patients with a follow-up of at least 6 months (mean age 75 yo, 9F, 7M, 11 PJI, 5 FRI). All microbiological isolates were tetracycline-susceptible staphylococci and for this reason a minocycline-based COAS was adopted after debridement and 3 months of antibiogram-guided antibiotic treatment. Patient monitoring was carried out on a clinical basis, with bimonthly execution of the inflammation indices and serial radiolabeled leukocyte scintigraphy (LS). The overall median time of COAS follow-up was 15 months (min 6-max 30). Moreover, 62.5% of patients were still taking COAS with no relapse after cure at the last evaluation available. Clinical failure with a relapse of the infection was observed in 37.5% of patients; interestingly, 50% of them had previously stopped COAS due to side effects of the antibiotic used. In the COAS follow-up, a combination of clinical, laboratory and LS evaluation seems to monitor the infection properly. COAS can be considered as an interesting approach in patients not suitable for standard treatments of PJI or FRI but it requires careful monitoring.

Liposomes-Based Drug Delivery Systems of Anti-Biofilm Agents to Combat Bacterial Biofilm Formation

All currently approved antibiotics are being met by some degree of resistance by the bacteria they target. Biofilm formation is one of the crucial enablers of bacterial resistance, making it an important bacterial process to target for overcoming antibiotic resistance. Accordingly, several drug delivery systems that target biofilm formation have been developed. One of these systems is based on lipid-based nanocarriers (liposomes), which have shown strong efficacy against biofilms of bacterial pathogens. Liposomes come in various types, namely conventional (charged or neutral), stimuli-responsive, deformable, targeted, and stealth. This paper reviews studies employing liposomal formulations against biofilms of medically salient gram-negative and gram-positive bacterial species reported recently. When it comes to gram-negative species, liposomal formulations of various types were reported to be efficacious against Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, and members of the genera Klebsiella, Salmonella, Aeromonas, Serratia, Porphyromonas, and Prevotella. A range of liposomal formulations were also effective against gram-positive biofilms, including mostly biofilms of Staphylococcal strains, namely Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus saprophyticus subspecies bovis, followed by Streptococcal strains (pneumonia, oralis, and mutans), Cutibacterium acnes, Bacillus subtilis, Mycobacterium avium, Mycobacterium avium subsp. hominissuis, Mycobacterium abscessus, and Listeria monocytogenes biofilms. This review outlines the benefits and limitations of using liposomal formulations as means to combat different multidrug-resistant bacteria, urging the investigation of the effects of bacterial gram-stain on liposomal efficiency and the inclusion of pathogenic bacterial strains previously unstudied.

Multifunctional Zn and Ag co-doped bioactive glass nanoparticles for bone therapeutic and regeneration

Bone cancer has traditionally been treated using surgery, radiotherapy, and/or chemotherapy. The nonspecific distribution of chemotherapy and implantable infections are significant risk factors for the failure of the bone to heal. Multifunctional zinc and silver co-doped bioactive glass nanoparticles (yAg-xZn-BGNPs) with a diameter of 150 ± 30 nm were successfully synthesized using modified sol-gel and two-step post-functionalization processes, tailored to provide antibacterial and anticancer activity whilst maintaining osteogenesis ability. Co-doped BGNPs with Zn and Ag did not significantly alter physicochemical properties, including size, morphology, glass network, and amorphous nature. Apatite-like layer was observed on the surface of yAg-xZn-BGNPs and resorbed in the simulated body fluid solution, which could increase their bioactivity. Human fetal osteoblast cell line (hFOB 1.19) treated with particles showed calcified tissue formation and alkaline phosphatase activity in the absence of osteogenic supplements in vitro, especially with 0.5Ag-1Zn-BGNPs. Moreover, these particles preferentially disrupted the metabolic activity of bone cancer cells (MG-63) and had an antibacterial effect against B. subtilis, E. coli, and S. aureus via the disc diffusion method. This novel 0.5Ag-1Zn-BGNP and 1Ag-1Zn-BGNPs, with wide-ranging ability to stimulate bone regeneration, to inhibit bone cancer cell proliferation, and to prevent bacterial growth properties, may provide a feasible strategy for bone cancer treatment. The 0.5Ag-1Zn-BGNPs and 1Ag-1Zn-BGNPs can be applied for the preparation of scaffolds or filler composites using in bone tissue engineering.

Treatment of Enterococcus faecalis Infective Endocarditis: A Continuing Challenge

Today, Enterococcus faecalis is one of the main causes of infective endocarditis in the world, generally affecting an elderly and fragile population, with a high mortality rate. Enterococci are partially resistant to many commonly used antimicrobial agents such as penicillin and ampicillin, as well as high-level resistance to most cephalosporins and sometimes carbapenems, because of low-affinity penicillin-binding proteins, that lead to an unacceptable number of therapeutic failures with monotherapy. For many years, the synergistic combination of penicillins and aminoglycosides has been the cornerstone of treatment, but the emergence of strains with high resistance to aminoglycosides led to the search for new alternatives, like dual beta-lactam therapy. The development of multi-drug resistant strains of Enterococcus faecium is a matter of considerable concern due to its probable spread to E. faecalis and have necessitated the search of new guidelines with the combination of daptomycin, fosfomycin or tigecycline. Some of them have scarce clinical experience and others are still under investigation and will be analyzed in this review. In addition, the need for prolonged treatment (6–8 weeks) to avoid relapses has forced to the consideration of other viable options as outpatient parenteral strategies, long-acting administrations with the new lipoglycopeptides (dalbavancin or oritavancin), and sequential oral treatments, which will also be discussed.

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.

Beyond the Risk of Biofilms: An Up-and-Coming Battleground of Bacterial Life and Potential Antibiofilm Agents

Microbial pathogens and their virulence factors like biofilms are one of the major factors which influence the disease process and its outcomes. Biofilms are a complex microbial network that is produced by bacteria on any devices and/or biotic surfaces to escape harsh environmental conditions and antimicrobial effects. Due to the natural protective nature of biofilms and the associated multidrug resistance issues, researchers evaluated several natural anti-biofilm agents, including bacteriophages and their derivatives, honey, plant extracts, and surfactants for better destruction of biofilm and planktonic cells. This review discusses some of these natural agents that are being put into practice to prevent biofilm formation. In addition, we highlight bacterial biofilm formation and the mechanism of resistance to antibiotics.

Do Anti-Biofilm Antibiotics Have a Place in the Treatment of Diabetic Foot Osteomyelitis?

The choice of antibiotic regimens for use in patients presenting with diabetic foot osteomyelitis and their duration differs according to the situation. Antibiotics play a more important role in the medical option where no infected bone has been resected, while their role is reduced but not negligible in the case of surgical options. Some studies have reported the presence of biofilm structures in bone samples taken from patients with diabetic foot osteomyelitis, which raises the question of the place of anti-biofilm antibiotic regimens in this setting. During the last two decades, clinical studies have suggested a potential benefit for anti-biofilm antibiotics, mainly rifampicin against staphylococci and fluoroquinolones against gram-negative bacilli. However, no data from randomized controlled studies have been reported so far. The present work provides a summary of the available data on the question of the place of anti-biofilm antibiotics for the treatment of diabetic foot osteomyelitis, but also the potential limitations of such treatments.

Growth and prevalence of antibiotic-resistant bacteria in microplastic biofilm from wastewater treatment plant effluents

It is accepted that Microplastic (MP) biofilms accumulates antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) in water. ARB/ARGs and MPs are emerging pollutants of concern due to various associated health risks. The objective of this study was to 1) investigate the ARB community in a pilot-scale wastewater treatment plant (WWTP) effluent, 2) to study and visualize the ARB/ARGs in MP biofilm grown in WWTP effluent and tap water, and 3) to analyze microplastic adherent ARB/ARGs in the biofilm and planktonic ARB/ARGs in the filtrate under controlled conditions. Results indicated the dominance of Pseudomonas, Aeromonas, and Bacillus among isolated ARB in WWTP effluent. Representative resistance strains were incubated in 300 mL water containing commercial polystyrene beads of 300550 μm diameter (MP) in a series of batch experiments. Microbiological, molecular, and microscopic analyses were performed by enumeration, 16srRNA, real-time polymerase chain reaction (qPCR), and Field Emission-Scanning Electron Microscopy (FEG-SEM) techniques. The analyzed viable ARB indicated an increasing trend in MP biofilms between days 3 and 5. It further decreased on days 7 and 9. The prevalence of ARB in the filtrate and MP biofilm varied as a function of time and TOC level, while no significant impacts were observed for minor temperature variation, low antibiotic pressure, and increased MP mass with few exceptions. Relative abundance of ARGs (vanA, sul1) and integron integrase gene (intl1) in MP biofilm were significantly different across different TOC levels, time, and antibiotic pressure. ARGs and intl1 were detected in the MP biofilm in tap water and WWTP effluent on day 30.

Determination of the Elution Capacity of Dalbavancin in Bone Cements: New Alternative for the Treatment of Biofilm-Related Peri-Prosthetic Joint Infections Based on an In Vitro Study

Antibiotic-loaded bone cement is the most widely used approach for the treatment of biofilm-induced septic sequelae in orthopedic surgery. Dalbavancin is a lipoglycopeptide that acts against Gram-positive bacteria and has a long half-life, so we aimed to assess whether it could be a new alternative drug in antibiotic-loaded bone cement for the treatment of periprosthetic joint infections. We assessed the elution capacity of dalbavancin and compared it with that of vancomycin in bone cement. Palacos®R (Heraeus Medical GmbH, Wehrheim, Germany) bone cement was manually mixed with each of the antibiotics studied at 2.5% and 5%. Three cylinders were obtained from each of the mixtures; these were weighed and incubated in 5 mL phosphate-buffered saline at 37°C under shaking for 1 h, 2 h, 4 h, 8 h, 24 h, 48 h, 168 h, and 336 h. PBS was replenished at each time point. The samples were analyzed using high-performance liquid chromatography (vancomycin) and mass cytometry (dalbavancin). Elution was higher than the minimum inhibitory concentration (MIC)90 for both antibiotics after 14 days of study. The release of vancomycin at 14 days was higher than of dalbavancin at each concentration tested (p = 0.05, both). However, the cumulative release of 5% dalbavancin was similar to that of 2.5% vancomycin (p = 0.513). The elution capacity of dalbavancin reached a cumulative concentration similar to that of vancomycin. Moreover, considering that the MIC90 of dalbavancin is one third that of vancomycin (0.06 mg/L and 2 mg/L, respectively) and given the long half-life of dalbavancin, it may be a new alternative for the treatment of biofilm-related periprosthetic infections when loaded in bone cement.

Role of Biofilm in Bacterial Infection and Antimicrobial Resistance

Biofilm refers to the complex, sessile communities of microbes found either attached to a surface or buried firmly in an extracellular matrix as aggregates. Microbial flora which produces biofilm manifests an altered growth rate and transcribes genes that provide them resistance to antimicrobial and host immune systems. Biofilms protect the invading bacteria against the immune system of the host via impaired activation of phagocytes and the complement system. Biofilm-producing isolates showed greater multidrug resistance than non-biofilm producers. Biofilm causes antibiotic resistance through processes like chromosomally encoded resistant genes, restriction of antibiotics, reduction of growth rate, and host immunity. Biofilm formation is responsible for the development of superbugs like methicillin-resistant Staphylococcus aureus, vancomycin-resistant Staphylococcus aureus, and metallo-beta-lactamase producing Pseudomonas aeruginosa. Regular monitoring of antimicrobial resistance and maintaining hygiene, especially in hospitalized patients are required to control biofilm-related infections in order to prevent antimicrobial resistance.

Population Pharmacokinetic and Pharmacodynamic Analysis of Dalbavancin for Long-Term Treatment of Subacute and/or Chronic Infectious Diseases: The Major Role of Therapeutic Drug Monitoring

A population pharmacokinetic analysis of dalbavancin was conducted in patients with different infection sites. Non-linear mixed effect modeling was used for pharmacokinetic analysis and covariate evaluation. Monte Carlo simulations assessed the probability of target attainment (PTA) of total dalbavancin concentration ≥ 8.04 mg/L over time (associated with ≥90% probability of optimal pharmacodynamic target attainment of fAUC24h/MIC > 111.1 against S. aureus) associated with a single or double dosage, one week apart, of 1000 or 1500 mg in patients with different classes of renal function. Sixty-nine patients with 289 concentrations were included. Most of them (53/69, 76.8%) had bone and joint infections. A two-compartment model adequately fitted dalbavancin concentration−time data. Creatinine clearance (CLCR) was the only covariate associated with dalbavancin clearance. Monte Carlo simulations showed that, in patients with severe renal dysfunction, the 1000 mg single or double one week apart dosage may ensure optimal PTAs of 2 and 5 weeks, respectively. In patients with preserved renal function, the 1500 mg single or double one-week apart dosage may ensure optimal PTAs of 2 and 4 to 6 weeks, respectively. Therapeutic drug monitoring should be considered mandatory for managing inter-individual variability and for supporting clinicians in long-term treatments of subacute and chronic infections.

The Current Knowledge on the Pathogenesis of Tissue and Medical Device-Related Biofilm Infections

Biofilm is the trigger for the majority of infections caused by the ability of microorganisms to adhere to tissues and medical devices. Microbial cells embedded in the biofilm matrix are highly tolerant to antimicrobials and escape the host immune system. Thus, the refractory nature of biofilm-related infections (BRIs) still represents a great challenge for physicians and is a serious health threat worldwide. Despite its importance, the microbiological diagnosis of a BRI is still difficult and not routinely assessed in clinical microbiology. Moreover, biofilm bacteria are up to 100–1000 times less susceptible to antibiotics than their planktonic counterpart. Consequently, conventional antibiograms might not be representative of the bacterial drug susceptibility in vivo. The timely recognition of a BRI is a crucial step to directing the most appropriate biofilm-targeted antimicrobial strategy.

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.

Antimicrobial Resistance, Biofilm Formation, and Virulence Genes in Enterococcus Species from Small Backyard Chicken Flocks

Backyard birds are small flocks that are more common in developing countries. They are used for poultry meat and egg production. However, they are also implicated in the maintenance and transmission of several zoonotic diseases, including multidrug-resistant bacteria. Enterococci are one of the most common zoonotic bacteria. They colonize numerous body sites and cause a wide range of serious nosocomial infections in humans. Therefore, the objective of the present study was to investigate the diversity in Enterococcus spp. in healthy birds and to determine the occurrence of multidrug resistance (MDR), multi-locus sequence types, and virulence genes and biofilm formation. From March 2019 to December 2020, cloacal swabs were collected from 15 healthy backyard broiler flocks. A total of 90 enterococci strains were recovered and classified according to the 16S rRNA sequence into Enterococcus faecalis (50%); Enterococcus faecium (33.33%), Enterococcus hirae (13.33%), and Enterococcus avium (3.33%). The isolates exhibited high resistance to tetracycline (55.6%), erythromycin (31.1%), and ampicillin (30%). However, all of the isolates were susceptible to linezolid. Multidrug resistance (MDR) was identified in 30 (33.3%) isolates. The enterococci AMR-associated genes ermB, ermA, tetM, tetL, vanA, cat, and pbp5 were identified in 24 (26.6%), 11 (12.2%), 39 (43.3%), 34 (37.7%), 1 (1.1%), 4 (4.4%), and 23 (25.5%) isolates, respectively. Of the 90 enterococci, 21 (23.3%), 27 (30%), and 36 (40%) isolates showed the presence of cylA, gelE, and agg virulence-associated genes, respectively. Seventy-three (81.1%) isolates exhibited biofilm formation. A statistically significant correlation was obtained for biofilm formation versus the MAR index and MDR. Multi-locus sequence typing (MLST) identified eleven and eight different STs for E. faecalis and E. faecium, respectively. Seven different rep-family plasmid genes (rep1–2, rep3, rep5–6, rep9, and rep11) were detected in the MDR enterococci. Two-thirds (20/30; 66.6%) of the enterococci were positive for one or two rep-families. In conclusion, the results show that healthy backyard chickens could act as a reservoir for MDR and virulent Enterococcus spp. Thus, an effective antimicrobial stewardship program and further studies using a One Health approach are required to investigate the role of backyard chickens as vectors for AMR transmission to humans.