Comparative Efficacy of Topical Versus Systemic Teicoplanin in Experimental Model of Wound Infections

Our Experience over 20 Years: Antimicrobial Peptides against Gram Positives, Gram Negatives, and Fungi

Antibiotic resistance is rapidly increasing, and new anti-infective therapies are urgently needed. In this regard, antimicrobial peptides (AMPs) may represent potential candidates for the treatment of infections caused by multiresistant microorganisms. In this narrative review, we reported the experience of our research group over 20 years. We described the AMPs we evaluated against Gram-positive, Gram-negative, and fungi. In conclusion, our experience shows that AMPs can be a key option for treating multiresistant infections and overcoming resistance mechanisms. The combination of AMPs allows antibiotics and antifungals that are no longer effective to exploit the synergistic effect by restoring their efficacy. A current limitation includes poor data on human patients, the cost of some AMPs, and their safety, which is why studies on humans are needed as soon as possible.

New insight into old and new antimicrobial molecules targeting quorum sensing for MRSA wound infection

MRSA represents one of the largest problems in wound healing as a result of its increasing incidence and the complex therapeutic approach required to treat it. The need for new solutions to overcome antibiotic resistance led to the development of antimicrobial molecules that are effective at blocking quorum sensing. This special report provides an up-to-date review, based on the latest evidence in the literature, of old and new molecules that can positively influence the process of wound healing via their action on MRSA quorum sensing. Quorum sensing-inhibiting molecules, applied topically or injected in situ, have excellent potential to improve both MRSA eradication and quality of wound healing, especially when combined with conventional systemic MRSA therapy. Further human studies are needed to evaluate the efficacy of these molecules.

New Perspectives on Old and New Therapies of Staphylococcal Skin Infections: The Role of Biofilm Targeting in Wound Healing

Among the most common complications of both chronic wound and surgical sites are staphylococcal skin infections, which slow down the wound healing process due to various virulence factors, including the ability to produce biofilms. Furthermore, staphylococcal skin infections are often caused by methicillin-resistant Staphylococcus aureus (MRSA) and become a therapeutic challenge. The aim of this narrative review is to collect the latest evidence on old and new anti-staphylococcal therapies, assessing their anti-biofilm properties and their effect on skin wound healing. We considered antibiotics, quorum sensing inhibitors, antimicrobial peptides, topical dressings, and antimicrobial photo-dynamic therapy. According to our review of the literature, targeting of biofilm is an important therapeutic choice in acute and chronic infected skin wounds both to overcome antibiotic resistance and to achieve better wound healing.

Impetigo Animal Models: A Review of Their Feasibility and Clinical Utility for Therapeutic Appraisal of Investigational Drug Candidates

Impetigo (school sores), a superficial skin infection commonly seen in children, is caused by the gram-positive bacteria Staphylococcus aureus and/or Streptococcus pyogenes. Antibiotic treatments, often topical, are used as the first-line therapy for impetigo. The efficacy of potential new antimicrobial compounds is first tested in in vitro studies and, if effective, followed by in vivo studies using animal models and/or humans. Animal models are critical means for investigating potential therapeutics and characterizing their safety profile prior to human trials. Although several reviews of animal models for skin infections have been published, there is a lack of a comprehensive review of animal models simulating impetigo for the selection of therapeutic drug candidates. This review critically examines the existing animal models for impetigo and their feasibility for testing the in vivo efficacy of topical treatments for impetigo and other superficial bacterial skin infections.

Colistin enhances therapeutic efficacy of daptomycin or teicoplanin in a murine model of multiresistant Acinetobacter baumannii sepsis. Diagn Microbiol Infect Dis. 2016;86:392-398. [PMID: 27712928 DOI: 10.1016/j.diagmicrobio.2016.09.010]

We investigated the efficacy of colistin combined with teicoplanin or daptomycin in an experimental mouse model of multiresistant Acinetobacter baumannii infection. Animal received intraperitoneally 1ml saline containing 2×10¹⁰CFU of A. baumannii. Colistin, daptomycin, teicoplanin, and colistin plus daptomycin or teicoplanin were given by intraperitoneal administration 2h after bacterial challenge. A control group received sodium chloride solution. In the in vitro study A. baumannii showed to be susceptible only to colistin with MIC of 2mg/l. In the in vivo study, colistin alone showed a good antimicrobial efficacy. When combined with teicoplanin or daptomycin, colistin produced the lowest bacterial and the best survival rates. In immunological studies, when colistin was associated to daptomycin or teicoplanin, both the number and the cytotoxic activity of NK cells increased. In conclusion, colistin combined with teicoplanin or daptomycin may improve the therapy of multiresistant A. baumannii infection.

Effectiveness of antimicrobial photodynamic therapy with a single treatment of RLP068/Cl in an experimental model of Staphylococcus aureus wound infection

BACKGROUND

Chronic leg ulceration is a common health problem. It is well known that a clinically relevant bacterial load in chronic cutaneous wounds interferes significantly with the normal process of healing. Staphylococcus aureus is the most important representative of the staphylococcal group which causes clinically relevant infections within immunocompetent patients.

OBJECTIVES

To investigate the efficacy of a single treatment of antimicrobial photodynamic therapy (APDT) with RLP068/Cl in a mouse model of a surgical wound infection induced with a methicillin-resistant strain of S. aureus (MRSA).

METHODS

Wounds, established through the panniculus carnosus of BALB/c and CD1 mice, were inoculated with 5 x 10(7) c.f.u. of MRSA. Mice were randomized into four groups respectively receiving no treatment, APDT with placebo, APDT with a new phthalocyanine derivative (RLP068/Cl) and intraperitoneal teicoplanin.

RESULTS

On day 2 from infection, a strong reduction of bacterial counts (≈ 3 logs) was observed in mice treated with RLP068/Cl in comparison with infected untreated mice. On day 9 from infection, a comparable and significant (≈ 2 logs) reduction of bacterial counts was found in mice treated with RLP068/Cl or with teicoplanin. At this time, histological examinations revealed that wounds treated with RLP068/Cl showed a complete re-epithelialization with a continuous epithelial lining.

CONCLUSIONS

The results of the in vivo study demonstrated that APDT with RLP068/Cl may be useful in the management of chronic infected wounds, accelerating the repair process through a significant bacterial inhibition.

Biodegradable microspherical implants containing teicoplanin for the treatment of methicillin-resistant Staphylococcus aureus osteomyelitis

BACKGROUND

The aim of this study was to prepare poly(d,l-lactide-co-glycolide) (PLGA) microspherical implants containing teicoplanin (TCP) using a double emulsion solvent evaporation method and to evaluate its efficacy for the local treatment of chronic osteomyelitis.

METHODS

The particle size and distribution, morphological characteristics, thermal behaviour, drug content, encapsulation efficiency and in vitro release assessments of the formulations were carried out. Sterile TCP–PLGA microspheres were implanted in the proximal tibia of rats with methicillin resistant Staphylococcus aureus (MRSA) osteomyelitis. After 3 weeks of treatment, bone samples were analysed with a microbiological assay and evaluated histopathologically.

RESULTS

Microspheres between the size ranges of 2.01 and 3.91 μm were obtained. Production yield of all formulations was found to be higher than 82% and encapsulation efficiencies of 33.6–69.8% were obtained. DSC thermogram showed that the TCP was in an amorphous state in microspheres. In vitro drug release studies had indicated that the drug release rate of microspheres was decreased upon increasing the polymer:drug ratio. Based on the in vivo data, rats treated with implants and intramuscular injection showed 1.7 × 10(3) ± 1.3 × 10(3) and 5.8 × 10(4) ± 5.3 × 10(4) colony forming unit of MRSA in 1 g bone samples (CFU/g), respectively (P < 0.01).

CONCLUSIONS

The in vitro and in vivo studies had shown that the TCP–PLGA microspheres were effective for the treatment of chronic osteomyelitis in an animal experimental model. Hence, these microspheres may be potentially useful in the clinical setting with the need for further investigation for optimal dosing of TCP–PLGA microspheres.

The interaction of mannose binding lectin (MBL) with mannose containing glycopeptides and the resultant potential impact on invasive fungal infection

Mannnose-binding lectin (MBL) binds oligosaccharides on the surface of microorganisms to form complexes that activate the complement cascade and facilitate phagocytosis. Teicoplanin and dalbavancin glycopeptide antibiotics possess N-acetyl glucosamine and mannose oligosaccharides that may bind MBL. Pharmaceuticals capable of binding to MBL may decrease clearance of significant pathogens such as yeast. An invasive candidemia murine model was utilized to evaluate differences in survival between mannose- and teicoplanin-treated groups compared to a control group administered normal saline. Three groups of BALB/c mice were injected with Candida albicans ATCC 44858 (1.4 x 10(6) CFU). Pharmaceutical agents were administered 2 h pre-infection and 8 h post-infection. In vivo cumulative survival at 52 h revealed 10%, 30% and 90% survival rates for mice administered mannose, teicoplanin, and saline, respectively. There was 0% survival for mice given mannose or teicoplanin at 56 h, compared with 70% for the normal saline treated mice at the same time point (P < 0.05). This in vivo study shows 'accelerated progression of infection' for Candida-inoculated mice exposed to mannose or teicoplanin compared to those given normal saline. Further, protein polyacrylamide gel electrophoresis studies suggested a potential MBL-drug interaction which may attenuate complement activation, opsonization and phagocytosis.