Our meeting with these experts provided valuable insight into the growing issue of antibiotic resistance in our region. In Quebec, while there are numerous cases of antibiotic resistance, instances involving multi-resistant bacteria remain relatively rare—though they are on the rise. Dr. Dumaresq reported having to import powerful antibiotics from the United States in desperate attempts to save patient's lives.

On the prevention side, much work remains to be done—both among healthcare professionals and within the general population. Alarmingly, approximately one in two antibiotic prescriptions is inadequate in terms of the molecule chosen, dosage, or duration. Many patients receive antibiotics unnecessarily, often due to precautionary prescribing or patient insistence. There is a widespread misconception that most infections lasting more than two to three days, such as the common cold, are bacterial and therefore require antibiotics. In reality, most of these infections are viral and typically resolve on their own within seven to ten days.

Dr. Dumaresq and his team emphasized the need for more public education campaigns—such as prevention ads—to raise awareness. This would not only improve individual health outcomes and slow the spread of resistance, but also help alleviate the pressure on our already overburdened healthcare system. Additionally, medical schools should invest more time and resources in educating future physicians on appropriate antibiotic use. Updated clinical guidelines should also be developed to support practicing physicians across all specialties. A key message to promote is that longer courses of antibiotics are not always better. In healthy, immunocompetent individuals, the current best practice is to prescribe antibiotics only for as long as necessary to allow the immune system to eliminate the remaining infection. This approach helps preserve the patient’s microbiome and reduces the risk of resistance.

We also discussed the applicability of our project. Dr. Dumaresq noted that superficial skin infections, such as diabetic foot ulcers, generally respond well to current antibiotics due to the high dosages used. He encouraged us to explore additional applications such as sterilization of inert surfaces, treatment of deep tissue infections, sepsis, and infections related to medical implants (e.g., hip prostheses). These types of infections are often caused by gram-positive bacteria like Staphylococcus aureus. While our project focuses on gram-negative bacteria—particularly Klebsiella pneumoniae—these suggestions are valuable for future research directions. Dr. Dumaresq reassured us though that K. pneumoniae is a highly relevant and concerning pathogen, making it a valid target for our work.

Finally, he expressed confidence that our NIR laser approach would be effective in disrupting biofilms. He also did not foresee a significant risk of bacteria developing increased resistance to biofilms in response to NIR exposure.

The infection prevention and control program and Dr. Dumaresq helped provide valuable insights into the reality of public health and clinical services. The discussion enabled us to understand that there is still a lot of prevention to accomplish for the public. We also improved our understanding about how the infection appears in the patient and other possible strains we could aim for. This part made us revisit our mode of action, with the NIR laser, as it would depend on the type of infection.

We have also adjusted our communications with the aim of offering the public a popular information capsule on antibiotic resistance that non-scientific audiences can understand. Indeed, as Dr. Dumaresq and Ms. Fillion mentioned, it is important to promote education on this type of issue in order to raise awareness among the general population as much as possible.

Our meeting with Dr. Boisselier was particularly insightful, allowing us to gain a deeper understanding of the intrinsic therapeutic and biomedical properties of gold nanoparticles. She guided us through key considerations such as selecting the appropriate nanoparticle size based on the target siderophore, and choosing the optimal nanoparticle shape. Finally, Dr. Boisselier reassured us about the many advantages of using gold nanoparticles, including their rapid and straightforward synthesis, their ability to be internalized by bacteria, and the wide range of possible administration routes.

According to her expertise, rod-shaped gold nanoparticles — or gold nanorods — would be best suited for our project since they absorb near infrared light more efficiently. Indeed, spherical gold nanoparticles absorb visible light, around 520 nm. While rod-shaped gold nanoparticles can absorb up to around 800 nm, i.e. in the near infrared. Thanks to Dr. Boisselier, we also adapted the size of the gold nanoparticle used in our project, namely a very small rod-shaped gold nanoparticle, approximately 1-2 nm, since the size of aerobactin is also 1 nm. According to her, for efficient acquisition, the size of the ligand must be approximately the same as that of the nanoparticle.

One aspect of the project aimed to gain a deeper understanding of the internalization mechanism of siderophores and Fe³⁺ in general. A review of the literature highlights the central role of TonB-dependent transporters (TBDTs) in siderophore uptake. These membrane proteins, composed of a β-barrel structure with an additional Plug domain, present a complex mode of action that remains puzzling.

Consulting this expert helped us better define the research parameters of our project. His feedback prompted us to reconsider the model proposed in the literature, which involves the complete withdrawal of the plug domain, as he suggested that such a mechanism would likely introduce a significant intrinsic vulnerability in the bacteria. Furthermore, as a specialist in membrane biomodelling, his insights provided a deeper understanding of the expected dynamics of the TBDT within the membrane.

Ms. Quémener’s expertise in optics and lasers allowed us to deepen our understanding of proper laser use and the different types available. Indeed, the power of various lasers (watts) is an important factor to consider, especially in a biological context. Moreover, using a laser in a biological setting can be difficult to anticipate and requires careful planning of optical setups. However, using optical fibers could simplify laser implementation for our project.

Initially, our laser choices were centered around the wavelength to be used. However, thanks to our meeting with Ms. Quémener, we were able to revise our selection criteria to ensure optimal laser choice and usage. The absorption wavelength of the target molecules—gold nanoparticles and the molecular composition of Klebsiella pneumoniae—is undoubtedly a key criterion for laser selection. Nevertheless, we must also include calculations related to laser power (mW), duration of use (seconds), and emitted energy (℃) for optimal and safe use of lasers.