Nebulized Bacteriophages for Prophylaxis of Experimental Ventilator-Associated Pneumonia Due to Methicillin-Resistant Staphylococcus aureus

Bacteriophage cocktail shows no toxicity and improves the survival of Galleria mellonella infected with Klebsiella spp

Klebsiella spp. are causative agents of healthcare-associated infections in patients who are immunocompromised and use medical devices. The antibiotic resistance crisis has led to an increase in infections caused by these bacteria, which can develop into potentially life-threatening illnesses if not treated swiftly and effectively. Thus, new treatment options for Klebsiella are urgently required. Phage therapy can offer an alternative to ineffective antibiotic treatments for antibiotic-resistant bacteria infections. The aim of the present study was to produce a safe and effective phage cocktail treatment against Klebsiella pneumoniae and Klebsiella oxytoca, both in liquid in vitro culture and an in vivo Galleria mellonella infection model. The phage cocktail was significantly more effective at killing K. pneumoniae and K. oxytoca strains compared with monophage treatments. Preliminary phage cocktail safety was demonstrated through application in the in vivo G. mellonella model: where the phage cocktail induced no toxic side effects in G. mellonella. In addition, the phage cocktail significantly improved the survival of G. mellonella when administered as a prophylactic treatment, compared with controls. In conclusion, our phage cocktail was demonstrated to be safe and effective against Klebsiella spp. in the G. mellonella infection model. This provides a strong case for future treatment for Klebsiella infections, either as an alternative or adjunct to antibiotics.IMPORTANCEKlebsiella infections are a concern in individuals who are immunocompromised and are becoming increasingly difficult to treat with antibiotics due to their drug-resistant properties. Bacteriophage is one potential alternative therapy that could be used to tackle these infections. The present study describes the design of a non-toxic phage cocktail that improved the survival of Galleria mellonella infected with Klebsiella. This phage cocktail demonstrates potential for the safe and effective treatment of Klebsiella infections, as an adjunct or alternative to antibiotics.

Antimicrobial and Antibiofilm Coating of Dental Implants—Past and New Perspectives

Regarded as one of the best solutions to replace missing teeth in the oral cavity, dental implants have been the focus of plenty of studies and research in the past few years. Antimicrobial coatings are a promising solution to control and prevent bacterial infections that compromise the success of dental implants. In the last few years, new materials that prevent biofilm adhesion to the surface of titanium implants have been reported, ranging from improved methods to already established coating surfaces. The purpose of this review is to present the developed antimicrobial and antibiofilm coatings that may have the potential to reduce bacterial infections and improve the success rate of titanium dental implants. All referred coating surfaces showed high antimicrobial properties with effectiveness in biofilm control, while maintaining implant biocompatibility. We expect that by combining the use of oligonucleotide probes as a covering material with novel peri-implant adjuvant therapies, we will be able to avoid the downsides of other covering materials (such as antibiotic resistance), prevent bacterial infections, and raise the success rate of dental implants. The existing knowledge on the optimal coating material for dental implants is limited, and further research is needed before more definitive conclusions can be drawn.

Biomaterial-based delivery of antimicrobial therapies for the treatment of bacterial infections

The rise in antibiotic-resistant bacteria, including strains that are resistant to last-resort antibiotics, and the limited ability of antibiotics to eradicate biofilms, have necessitated the development of alternative antibacterial therapeutics. Antibacterial biomaterials, such as polycationic polymers, and biomaterial-assisted delivery of non-antibiotic therapeutics, such as bacteriophages, antimicrobial peptides and antimicrobial enzymes, have improved our ability to treat antibiotic-resistant and recurring infections. Biomaterials not only allow targeted delivery of multiple agents, but also sustained release at the infection site, thereby reducing potential systemic adverse effects. In this Review, we discuss biomaterial-based non-antibiotic antibacterial therapies for the treatment of community- and hospital-acquired infectious diseases, with a focus in in vivo results. We highlight the translational potential of different biomaterial-based strategies, and provide a perspective on the challenges associated with their clinical translation. Finally, we discuss the future scope of biomaterial-assisted antibacterial therapies.

WEB SUMMARY

The development of antibiotic tolerance and resistance has demanded the search for alternative antibacterial therapies. This Review discusses antibacterial biomaterials and biomaterial-assisted delivery of non-antibiotic therapeutics for the treatment of bacterial infectious diseases, with a focus on clinical translation.

Prospects of Inhaled Phage Therapy for Combatting Pulmonary Infections

With respiratory infections accounting for significant morbidity and mortality, the issue of antibiotic resistance has added to the gravity of the situation. Treatment of pulmonary infections (bacterial pneumonia, cystic fibrosis-associated bacterial infections, tuberculosis) is more challenging with the involvement of multi-drug resistant bacterial strains, which act as etiological agents. Furthermore, with the dearth of new antibiotics available and old antibiotics losing efficacy, it is prudent to switch to non-antibiotic approaches to fight this battle. Phage therapy represents one such approach that has proven effective against a range of bacterial pathogens including drug resistant strains. Inhaled phage therapy encompasses the use of stable phage preparations given via aerosol delivery. This therapy can be used as an adjunct treatment option in both prophylactic and therapeutic modes. In the present review, we first highlight the role and action of phages against pulmonary pathogens, followed by delineating the different methods of delivery of inhaled phage therapy with evidence of success. The review aims to focus on recent advances and developments in improving the final success and outcome of pulmonary phage therapy. It details the use of electrospray for targeted delivery, advances in nebulization techniques, individualized controlled inhalation with software control, and liposome-encapsulated nebulized phages to take pulmonary phage delivery to the next level. The review expands knowledge on the pulmonary delivery of phages and the advances that have been made for improved outcomes in the treatment of respiratory infections.

Searching for synergy: combining systemic daptomycin treatment with localised phage therapy for the treatment of experimental pneumonia due to MRSA

Objective

Bacteriophages (or phages) are viruses which infect and lyse bacteria. The therapeutic use of phages (phage therapy) has regained attention in the last decades as an alternative strategy to treat infections caused by antimicrobial-resistant bacteria. In clinical settings it is most likely that phages are administered adjunct to antibiotics. For successful phage therapy it is therefore crucial to investigate different phage-antibiotic combinations in vivo. This study aimed to elucidate the combinatorial effects of systemic daptomycin and nebulised bacteriophages for the treatment of experimental pneumonia due to methicillin-resistant Staphylococcus aureus (MRSA).

Results

Using a rat model of ventilator-associated pneumonia caused by MRSA, the simultaneous application of intravenous daptomycin and nebulised phages was not superior to aerophage therapy alone at improving animal survival (55% vs. 50%), or reducing bacterial burdens in the lungs, or spleen. Thus, this combination does not seem to be of benefit for use in patients with MRSA pneumonia.

Gram-Positive Pneumonia: Possibilities Offered by Phage Therapy

Pneumonia is an acute pulmonary infection whose high hospitalization and mortality rates can, on occasion, bring healthcare systems to the brink of collapse. Both viral and bacterial pneumonia are uncovering many gaps in our understanding of host–pathogen interactions, and are testing the effectiveness of the currently available antimicrobial strategies. In the case of bacterial pneumonia, the main challenge is antibiotic resistance, which is only expected to increase during the current pandemic due to the widespread use of antibiotics to prevent secondary infections in COVID-19 patients. As a result, alternative therapeutics will be necessary to keep this disease under control. This review evaluates the advantages of phage therapy to treat lung bacterial infections, in particular those caused by the Gram-positive bacteria Streptococcus pneumoniae and Staphylococcus aureus, while also highlighting the regulatory impediments that hamper its clinical use and the difficulties associated with phage research.

Progress and Pitfalls of Bacteriophage Therapy in Critical Care: A Concise Definitive Review

Supplemental Digital Content is available in the text.

Objective:

Bacterial infections caused by antibiotic-resistant pathogens are a major problem for patients requiring critical care. An approach to combat resistance is the use of bacterial viruses known as “phage therapy.” This review provides a brief “clinicians guide” to phage biology and discusses recent applications in the context of common infections encountered in ICUs.

Data Sources:

Research articles were sourced from PubMed using search term combinations of “bacteriophages” or “phage therapy” with either “lung,” “pneumonia,” “bloodstream,” “abdominal,” “urinary tract,” or “burn wound.”

Study Selection:

Preclinical trials using animal models, case studies detailing compassionate use of phage therapy in humans, and randomized controlled trials were included.

Data Extraction:

We systematically extracted: 1) the infection setting, 2) the causative bacterial pathogen and its antibiotic resistance profile, 3) the nature of the phage therapeutic and how it was administered, 4) outcomes of the therapy, and 5) adverse events.

Data Synthesis:

Phage therapy for the treatment of experimental infections in animal models and in cases of compassionate use in humans has been associated with largely positive outcomes. These findings, however, have failed to translate into positive patient outcomes in the limited number of randomized controlled trails that have been performed to date.

Conclusions:

Widespread clinical implementation of phage therapy depends on success in randomized controlled trials. Additional translational and reverse translational studies aimed at overcoming phage resistance, exploiting phage-antibiotic synergies, and optimizing phage administration will likely improve the design and outcome of future trials.

Exploring Virulence Factors and Alternative Therapies against Staphylococcus aureus Pneumonia

Pneumonia is an acute pulmonary infection associated with high mortality and an immense financial burden on healthcare systems. Staphylococcus aureus is an opportunistic pathogen capable of inducing S. aureus pneumonia (SAP), with some lineages also showing multidrug resistance. Given the high level of antibiotic resistance, much research has been focused on targeting S. aureus virulence factors, including toxins and biofilm-associated proteins, in an attempt to develop effective SAP therapeutics. Despite several promising leads, many hurdles still remain for S. aureus vaccine research. Here, we review the state-of-the-art SAP therapeutics, highlight their pitfalls, and discuss alternative approaches of potential significance and future perspectives.