Direct interactions between cationic liposomes and bacterial cells ameliorate the systemic treatment of invasive multidrug-resistant Staphylococcus aureus infections

Innovative Phospholipid Carriers: A Viable Strategy to Counteract Antimicrobial Resistance

The overuse and misuse of antibiotics have led to the emergence and spread of multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan-drug-resistant (PDR) bacteria strains, usually associated with poorer patient outcomes and higher costs. In order to preserve the usefulness of these life-saving drugs, it is crucial to use them appropriately, as also recommended by the WHO. Moreover, innovative, safe, and more effective approaches are being investigated, aiming to revise drug treatments to improve their pharmacokinetics and distribution and to reduce the onset of drug resistance. Globally, to reduce the burden of antimicrobial resistance (AMR), guidelines and indications have been developed over time, aimed at narrowing the use and diminishing the environmental spread of these life-saving molecules by optimizing prescriptions, dosage, and times of use, as well as investing resources into obtaining innovative formulations with better pharmacokinetics, pharmacodynamics, and therapeutic results. This has led to the development of new nano-formulations as drug delivery vehicles, characterized by unique structural properties, biocompatible natures, and targeted activities such as state-of-the-art phospholipid particles generally grouped as liposomes, virosomes, and functionalized exosomes, which represent an attractive and innovative delivery approach. Liposomes and virosomes are chemically synthesized carriers that utilize phospholipids whose nature is predetermined based on their use, with a long track record as drug delivery systems. Exosomes are vesicles naturally released by cells, which utilize the lipids present in their cellular membranes only, and therefore, are highly biocompatible, with investigations as a delivery system having a more recent origin. This review will summarize the state of the art on microvesicle research, liposomes, virosomes, and exosomes, as useful and effective tools to tackle the threat of antibiotic resistance.

Exploring Nanotechnology as a Strategy to Circumvent Antimicrobial Resistance in Bone and Joint Infections

Bone and joint infections (BJIs) are difficult to treat, necessitating antimicrobial therapy at high doses for an extended period of time, in some cases different from our local guidelines. As a consequence of the rise in antimicrobial-resistant organisms, drugs that were previously reserved for last-line defense are now being used as first line treatment, and the pill burden and adverse effects on patients are leading to nonadherence, encouraging antimicrobial resistance (AMR) to these last-resort medicines. Nanodrug delivery is the field of pharmaceutical sciences and drug delivery which combines nanotechnology with chemotherapy and/or diagnostics to improve treatment and diagnostic outcomes by targeting specific cells or tissues affected. Delivery systems based on lipids, polymers, metals, and sugars have been used in an attempt to provide a way around AMR. This technology has the potential to improve drug delivery by targeting the site of infection and using the appropriate amount of antibiotics to treat BJIs caused by highly resistant organisms. This Review aims to provide an in-depth examination of various nanodrug delivery systems used to target the causative agents in BJI.

Mohammed AS, Al-Sabati A. Formulation and evaluation of Yemeni potash alum as hydrophilic topical preparations against bacterial skin infections

Skin and soft tissue infections are common. Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, and Pseudomonas aeruginosa cause most bacterial skin infections. Yemen's alum is a natural mineral with potent antibacterial and antifungal activity. The current study aimed to verify Yemen alum's antibacterial activity against chosen bacterial strains to formulate a valuable topical preparation. We formulated twenty-three formulations involving four non-adjusted aqueous solutions, eight adjusted pH aqueous solutions, three Oil/Water cream formulations, and eight glycerin solutions, all with different alum concentrations. After that, we evaluated the antibacterial efficacy against the selected bacterial strains. Additionally, we performed stability testing (almost six weeks) to determine the chosen preparations' estimated shelf life (t90).  Alum showed antibacterial activity against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, and Pseudomonas aeruginosa. Finally, it was concluded that Oil/Water cream (10% alum) is viable preparation for large-scale production.

On-Demand Multifunctional Electrostatic Complexation for Synergistic Eradication of MRSA Biofilms

Recently, methicillin-resistant Staphylococcus aureus (MRSA) severely threatened the public health, especially when the biofilms developed. Although the biofilm eradication capability of nanoparticles (NPs) has been proposed and confirmed, efficient biofilm penetration and retention are still a big challenge. To solve this problem, a multifunctional electrostatic complexation (denoted as TDZ-G4@CA) was constructed for biofilm combination therapy. TDZ-G4@CA was composed of a TDZ-grafted amino-ended poly(amidoamine) dendrimer (TDZ-PAMAM) as the inner core and cis-aconitic anhydride-modified d-tyrosine (CA-Tyr) wrapped outside via electrostatic interaction. In our design, TDZ-G4@CA could simultaneously reduce the particle size and reverse the surface charge under an acidic microenvironment, which was designed for efficient biofilm penetration and retention. Meanwhile, the on-demand two-step sequential delivery of biofilm dispersal and antibacterial agents was also obtained. The acid responsiveness of TDZ-G4@CA triggered the immediate release of d-Tyr to damage the matrix of the biofilm. Subsequently, TDZ-G4 could penetrate over the depth of the biofilm and bind tightly to MRSA, which could enhance the permeability of the bacterial membrane for TDZ internalization. Additionally, TDZ exhibited a sustained-release pattern as a response to lipase to maintain an effective bactericidal concentration for a long time. As expected, in vitro experiments demonstrated that surface charge/particle size-adaptive TDZ-G4@CA with a sequential delivery strategy exhibited intensive infiltration in the biofilm matrix and excellent biofilm eradication capabilities. Afterward, in vivo experimental results also confirmed the prolonged circulation time and comprehensive therapeutic efficacy of TDZ-G4@CA against MRSA-induced subcutaneous abscess without any systemic side effects. Based on the comprehensive evaluation of the therapeutic outcome, the electrostatic complexation (TDZ-G4@CA) can serve as a promising strategy for enhanced antibiotic therapy for combating biofilm-associated infections.