Diseases are caused by a number of different mechanisms, but the main culprits are pathogens that can travel from one host to another through different media. Whether the pathogen (bacteria or virus) is killed or stopped by a drug, depends on the machinery of the pathogen. For example, bacteria can be either killed by antibiotics or may be antibiotic resistant, while viruses are not affected by antibiotics at all and may be targeted by an antiviral drug.
It can be established,then, that various pathogens are affected by various drugs that act on the pathogen’s cellular machinery. However, a more inclusive and general approach is available via photodynamic therapy (PDT).
Despite being discovered in the early 20th Century, PDT was not further developed until multidrug resistant pathogens emerged.[i][ii] The end of the so-called ‘antibiotic era’ led to a greater rate of infections, especially in those with immunosuppression, e.g. cancer patients and diabetics, where the patients were utterly vulnerable. A therapy was needed that would not cause resistance to treatment as readily, and photodynamic therapy was called to action.[iii]
Photodynamic therapy uses low power laser light and a photosensitizing chemical, to kill cells in the presence of oxygen. One of the most common photosensitizers include riboflavin (vitamin B2), porphyrins, ALA and crystal blue. According to a study done on 20 patients, blood irradiation killed malarial parasite, Plasmodium falciparum in 9 days in 88.9% patients. This is a nod to the antimicrobial properties of photodynamic therapy.[iv]
Nosocomial infections like Klebsiella, S. aureus, Enterobacteriaceae and Bacteroides which have a high occurrence rate are one of the main causes of antibiotic resistance. Treatment with PDT is more appropriate. Similarly, postsurgical infections such as necrotizing fasciitis, gas gangrene (Clostridium spp.), necrotizing cellulitis and Fournier’s gangrene where repeated excisions of affected tissue are necessary, can lead to further infections and can be treated with PDT. In these cases, PDT can reduce the chances of secondary infection.[v]
In addition to bacterial and parasitic infections, photodynamic therapy has been honed in antifungal[vi] and antiviral[vii] application as well. Various studies along the course of time show that PDT has been successfully utilized in limiting HIV by inhibiting viral attachment and penetration into human cells, inactivation of free viral particles and selective destruction of infected white cells.[viii][ix]
The technically advanced Weber Laser system was developed utilizing multiple wavelengths for various diseases along with external, intravenous, interstitial and intra-articular application methods. It is used world-wide for multiple diseases and as a broad-spectrum protection against transmission of existing and emerging pathogens, such as MERS-CoV. This laser therapy combines riboflavin or vitamin B2 (photosensitizer) and low power laser to destroy pathogens, prevent replication of WBCs, all the while sparing platelets and RBCs.[x][xi] Additionally, the blue wavelength (447 nM) has an anti-inflammatory effect, increases Nitric Oxide (NO), improves microcirculation and tissue oxygen utilization.
These results are hard to achieve via antibiotics, antimicrobials and antivirals without causing a multidrug resistance in pathogens but can be fulfilled without adverse side effects by photodynamic therapy, of which the Weber Laser system is forefront, utilizing easily available riboflavin as a photosensitizer.
In light of recent events, where COVID -19 is rampaging the streets worldwide and has wreaked havoc in every neighborhood, people are fearful of not only the complications of the disease itself but secondary infections alongside it. What started as a small ‘flu-like symptomatic disease’ in Wuhan has people gasping for air in all four corners of the world. The high-grade fever, cough, tightness of the chest and pneumonia has left doctors and patients dumbfound as there is yet to determine a likely treatment.
Several incidences of chloroquine and hydrochloroquine poisoning[xii], and associated deaths, have led to the search of a new treatment – one that does not possess such deadly adverse effects.
It has been proposed that photodynamic therapy may be able to kill the COVID-19 pathogen. Being effective against previous MERS-CoV pandemic, there could be potential in it to treat COVID-19 as well.[xiii] The use of the Weber Laser system may cause a change in fate for patients— especially since development of vaccines and proper definitive treatment of COVID-19 are still under way.
[i] Chung, P. Y. (2016). The emerging problems of Klebsiella pneumoniae infections: carbapenem resistance and biofilm formation. FEMS microbiology letters, 363(20).
[ii] Valenzuela-Valderrama, M., González, I. A., & Palavecino, C. E. (2019). Photodynamic treatment for multidrug-resistant Gram-negative bacteria: perspectives for the treatment of Klebsiella pneumoniae infections. Photodiagnosis and photodynamic therapy.
[iii] Weber, M.H. & Fußgänger-May, Th & Wolf, T. (2007). Intravenous laser blood irradiation – Introduction of a new therapy. Deutsche Zeitschrift fur Akupunktur. 50. 12-23.
[iv] Hamblin, M. R., & Hasan, T. (2004). Photodynamic therapy: a new antimicrobial approach to infectious disease?. Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, 3(5), 436–450. https://doi.org/10.1039/b311900a
[v] Rossoni, R. D., Junqueira, J. C., Santos, E. L. S., Costa, A. C. B., & Jorge, A. O. C. (2010). Comparison of the efficacy of Rose Bengal and erythrosin in photodynamic therapy against Enterobacteriaceae. Lasers in medical science, 25(4), 581-586.
[vi] Donnelly, R. F., McCarron, P. A., & Tunney, M. M. (2008). Antifungal photodynamic therapy. Microbiological research, 163(1), 1-12.
[vii] Lim, M. E., Lee, Y. L., Zhang, Y., & Chu, J. J. H. (2012). Photodynamic inactivation of viruses using upconversion nanoparticles. Biomaterials, 33(6), 1912-1920.
[viii] Santus, R., Grellier, P., Schrével, J., Mazière, J. C., & Stoltz, J. F. (1998). Photodecontamination of blood components: advantages and drawbacks. Clinical hemorheology and microcirculation, 18(4), 299-308.
[ix] Mohr, H., Lambrecht, B., & Selz, A. (1995). Photodynamic virus inactivation of blood components. Immunological investigations, 24(1-2), 73-85.
[x] Cazenave, J. P., Follea, G., Bardiaux, L., Boiron, J. M., Lafeuillade, B., Debost, M., … & Michallet, M. (2010). A randomized controlled clinical trial evaluating the performance and safety of platelets treated with MIRASOL pathogen reduction technology. Transfusion, 50(11), 2362-2375.
[xi] Smith, J., & Rock, G. (2010). Protein quality in Mirasol pathogen reduction technology–treated, apheresis‐derived fresh‐frozen plasma. Transfusion, 50(4), 926-931.
[xiii] Focosi, D., Tang, J. W., Anderson, A. O., & Tuccori, M. (2020). CONVALESCENT BLOOD PRODUCT THERAPIES FOR COVID-19: A SYSTEMATIC REVIEW.
[xiv] Casadevall, A., & Pirofski, L. A. (2020). The convalescent sera option for containing COVID-19. The Journal of clinical investigation, 130(4).
 Mohr, H., Lambrecht, B., & Selz, A. (1995). Photodynamic virus inactivation of blood components. Immunological investigations, 24(1-2), 73-85.
 Cazenave, J. P., Follea, G., Bardiaux, L., Boiron, J. M., Lafeuillade, B., Debost, M., … & Michallet, M. (2010). A randomized controlled clinical trial evaluating the performance and safety of platelets treated with MIRASOL pathogen reduction technology. Transfusion, 50(11), 2362-2375.
 Smith, J., & Rock, G. (2010). Protein quality in Mirasol pathogen reduction technology–treated, apheresis‐derived fresh‐frozen plasma. Transfusion, 50(4), 926-931.
 Focosi, D., Tang, J. W., Anderson, A. O., & Tuccori, M. (2020). CONVALESCENT BLOOD PRODUCT THERAPIES FOR COVID-19: A SYSTEMATIC REVIEW.
 Casadevall, A., & Pirofski, L. A. (2020). The convalescent sera option for containing COVID-19. The Journal of clinical investigation, 130(4).