Russell Leong Joan Lee Zejia Chen Chelsea Zhang


Introduction: Antibiotic resistance is a major global health concern as many fatalities occur each year due to severe infections associated with it, such as sepsis. This research protocol hopes to address the issue of antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA) by using an alternative antibiotic therapy. Silver nanoparticles (AgNPs), which have antibiotic properties and low antibiotic resistance potential, will be administered in conjunction with stable and biocompatible branched amphiphilic peptide capsules (BAPCs). Surface functionalized ligands will be attached to the peptide capsules to target iron receptors essential to MRSA survival. By targeting its iron receptors, the bacteria will be unable to mutate in such a way that would attenuate its uptake of this antibiotic.

Methods: Testing will begin in vitro on MRSA cultures to assess the minimum inhibitory concentration of the various AgNP treatment groups. Constraints determining the minimum inhibitory concentration include a minimum 3-hour delay in bactericidal effect from application, and a 95% eradication efficacy. Drug efficacy will be evaluated via ex vivo and in vivo mice experiments, with off-target toxicity effects measured via BAPC targeted immunohistochemistry, and both serological and organ-based tests. Repeated in vivo treatments will be performed against a control to measure the relative antibiotic resistance advantages this treatment proposes. As this protocol requires the use of mice, ethics approval from the Canadian Council on Animal Care will be obtained prior to experimentation.

Results: It is expected that the AgNPs will be successfully encapsulated within the structurally-sound BAPCs and that the AgNPs will eradicate a significant amount of the MRSA present in the human body with minimal side effects. The in vitro, ex vivo and in vivo tests are likely to yield results that demonstrate that the most effective protocol in eradicating MRSA is to use AgNPs in BAPCs in conjunction with a vancomycin treatment. The proposal will likely satisfy the criteria for appropriate AgNP doses, which includes bactericidal effect in a time frame of hours, over 95% efficacy, and statistically significant reproducibility.

Discussion: Successful BAPC mediated delivery of AgNPs prove the potential for targeted antibiotic application against multidrug bacteria with lower risk of antibiotic resistance compared to conventional antibiotics. This proof of concept protocol demonstrates the potential for applying rational design of BAPCs as a delivery vector. Certain limitations, including off-target toxicity and redundant targeting are issues to be cognizant of and controlled.

Conclusion: This novel therapy can be considered as a preliminary step in overcoming antibiotic resistance. With appropriate modifications to the functional ligands attached to the BAPCs, the proposed drug mechanism could be applied to treat other bacterial strains. 

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Research Protocol