Antimicrobial resistance (AMR) represents a global public health challenge of paramount importance, as attested by its ever-growing presence in scientific studies and by its classification among the top ten priorities by the World Health Organization [1]. The latter estimates that the number of deaths related to antibiotic resistance exceeds 700,000 annually, with projections suggesting that this figure may exceed 10 million by 2050. Italy, our country, is the most severely affected nation in the European region, as reported by the latest data in 2019, which documented approximately 11,000 deaths for infections associated to AMR bacteria [4]
This phenomenon is primarily attributable to a restricted group of pathogenic microorganisms, commonly referred to as ESKAPE, which comprises Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter spp., Pseudomonas aeruginosa, and Escherichia coli. [2]
The magnitude of the issue has been underlined by a resolution adopted by the World Health Assembly on May 28th, 2019, which recognized the urgency of investing in "high-quality research and development, including basic research for antimicrobials, diagnostic technologies, vaccines, and alternative preventive measures across sectors, as well as ensuring access to safe, effective, affordable, and quality antimicrobials, diagnostic tools, and vaccines to those in need, while promoting effective stewardship" [1].
Additionally, if the awareness that this is an issue of enormous significance and impact on global public health, the situation is even worse if we consider the environmental aspects related to AMR, with a specific focus on the agricultural and veterinary aspects, from farming to livestocks and poultry farms. Indeed, as reported by FAO, the impact in the agricultural sector is relevant as it “causes production losses, damages livelihoods and jeopardizes food security. Moreover, AMR can spread among different hosts and the environment, and antimicrobial resistant microorganisms can contaminate the food chain” [3]. Moreover, it is estimated by the same organization that AMR, if not faced, may cumulatively result in 3.4 trillion USD loss1 in the world’s annual gross domestic product (GDP) in ten short years.
We were struck by the extent, gravity, and urgency of this problem, which requires prompt and effective action, and investigated how we could contribute to addressing it.
At the heart of this phenomenon lies the great difficulty in the search for new therapeutic molecules. The development costs for new antibiotics are difficult to sustain in the long term, and the timeline for development is not compatible with the speed at which this problem is advancing. For this reason, as suggested by numerous publications, a radically new approach is required.
The use of bacteriophages as treatment for bacterial infections has been one of the first ideas since their discovery. These viruses are capable of recognizing their target with extreme precision and inserting their genome inside it. Therefore this approach has been used to selectively target bacteria and kill them. [10, 11]
Starting from this problem and these premises, we have asked ourselves how to implement a new solution by leveraging the knowledge of synthetic biology. From this, PASTA (Phage Assisted Silencing Tool against AMR) was born. Our aim was not so much to find a definitive solution to this problem, but rather to develop a platform that would make research and development of innovative therapies more accessible, utilizing the standardization of parts offered by synthetic biology. Additionally, we wanted to take this opportunity to raise awareness about a neglected and little-known issue, namely antibiotic resistance.
The system we have developed does not seek to replace antibiotic therapy, as such an approach would quickly become futile due to the same evolutionary mechanism that is rendering antibiotics ineffective. Rather, it aims to complement antibiotic therapy through a synergistic approach that can be more effective.
PASTA is based on two components:
Details on how the two systems work are discussed in their respective pages.
But why use engineered phages instead of continuing to use wild-type phages, as done in several past studies? We have identified three main reasons:
During the development of our idea, we questioned ourselves and also consulted stakeholders regarding the most natural progression for a project of this kind. Initially, our perspective involved the utilization of engineered bacteriophages within a hydrogel [8] intended for treating surfaces, medical equipment, and prosthetics in hospitals. However, as our focus shifted towards addressing antibiotic-resistant infections, we engaged in discussions with relevant parties, particularly healthcare professionals, who expressed a willingness to incorporate such therapy into clinical practice (this topic is further explored in the section dedicated to human practices). Consequently, the next envisioned steps would involve validating a therapeutic approach by assessing the efficacy of this system in vitro on clinical isolates, followed by in vivo characterizations using animal models and hopefully one day by clinical studies to validate the therapeutic approach.