Researchers from the Research Center on Optics and Photonics (CEPOF) have managed to increase the sensitivity of the fungus Candida albicans drug treatment with therapy activated by light. The results of the study offer a promising alternative in the fight against antimicrobial resistance, an increasing global problem that occurs when bacteria, viruses, fungi and other parasites develop genetic mutations that make them resistant to drugs.
In the study, published in the journal Photochemistry and photobiologyThe researchers evaluated the photodynamic inactivation (PDI) combined with antifungal amphotericin B to control the growth of the fungus, in particular its forms of yeast (single cell) and hyphae (filamentous colony).
The results showed that the combination of the two treatments reduced the C. albicans Growth of 75% in the form of yeast and 87.5% in the form of hyphae. In addition, two PDI sessions have further increased antifungal efficiency, in particular against hyphae, which were more sensitive to treatment.
“It is a technique which consists in using a molecule (in this case of curcumin) and activating it with blue light. Activation, in the presence of oxygen, means that the molecule produces free radicals, thus inducing oxidative stress, killing or weakening pathogen, “explains Vanderlei Bagnato, Cepof coordinator, Fapespe Institut de Physique de São Carlos from the University of São Paulo (ISSC-USP) in Brazil. “In the case of C. albicansMainly in the hyphae, which form an almost impenetrable biofilm for drugs, photodynamic therapy has been able to “break” these colonies, resulting in the potentiation of the antifungal effect “.
The study involved photodynamic inactivation using 2.5 μm (micrometers) of curcumin, which was activated by 450 nm (nanometers) LEDs of light and different concentrations of the antifungal amb.
An imminent danger
C. albicans is naturally present in the human body and is generally harmless. However, this can cause skin manifestations such as chief or vaginal candidiasis. In more serious cases, the fungus can cause systemic candidiasis, invasive blood infection. This serious disease is diagnosed more frequently in intensive care units (USI) due to the growing number of immunocompromised patients and increased microbial resistance.
There is growing mushroom resistance, and C. albicans is no exception. It is a very common fungus, but there are already cases of patients who died of resistant systemic infections. Therefore, it is very important to anticipate the problem and present an alternative which allows a more effective fight against the fungus without side effects or the need for excessive use of drugs. “”
Gabriela Gomes Guimarães, Cepof researcher and first author of the study
Guimarães explains that the decision to start photodynamic inactivation tests on mushrooms using C. albicans was motivated by the two species’ morphologies. “The fungus forms yeasts and hyphae, which form biofilms. Therefore, the fact that he worked so well for C. albicans gives us confidence to perform new tests on other species, such as C. earAn emerging fungus which raises a concern, has shown resistance to treatment and can be fatal, “explains the researcher.
Food applications
In addition to testing the effects of photodynamic therapy on other fungal species that constitute a threat to human health, researchers will conduct food security studies. “The proof of principle that we have just published on C. albicans Allows us to carry out studies on the application of photodynamic therapy in food decontamination. Mushrooms are also a problem of contamination of cereals, for example. Therefore, our next step is to test the application of this technique in storage silos, for example, “plans Bagnato.
The Cepof led various laser research projects to advance treatments for bacteria, viruses and other diseases, including cancer and fibromyalgia (Find out more about: Agency.Fapesp.br/50500).
“The principle is always the same: activate a molecule with a laser so that it oxidizes. What varies in each case is the application, the amount of light, the color temperature, the amount of medication and the amount of pathogen eliminated or inactivated ”, sums up Bagnato.
Jennifer Soares, member of the CEPOF and recipient of a FAPESP scholarship, explains that researchers are also anxious to use molecules compatible with human health and the environment.
“Curcumin, for example, is a compound found in curry and has already been approved for use in humans. But there is also concern about how to apply light. Our studies have shown that blue light, due to its wavelength, is ideal for treating superficial infections such as in the throat. Infections, such as pneumonia, which requires suitable devices to light the chest area, ”she explains.
The Cepof also conducts studies focused on the treatment of cervical cancer by applying photosensitizing drugs and molecules through specific routes, such as intravaginal channel.
