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Antibiotics reinforced by light and dyes combat hospital superbugs
Combining photodynamic therapy with traditional antibiotics enhances drug efficacy and may reduce the need for high doses
A study developed by scientists from USP’s São Carlos Institute of Physics (IFSC) and Texas A&M University (USA) proposes an alternative to combat a hospital superbug. The study showed that combining photodynamic therapy, which uses light and special dyes, with traditional antibiotics enhances their effectiveness and reduces the need for high doses of medication.
The research targeted Klebsiella pneumoniae, a common bacterium in severe hospital infections, especially in patients with ventilator-associated pneumonia. Highly resistant to various antibiotics, this bacterium is one of the leading causes of death from hospital infections worldwide.
Koteswara Rao Yerra and Vanderlei Salvador Bagnato, authors of the study, tested the use of two dyes – methylene blue and photoditazine – which are activated by red LED light. This technique, called antimicrobial photodynamic therapy, generates reactive oxygen molecules that damage bacterial cells. The study examined the substances both individually and in combination with the antibiotics ciprofloxacin, gentamicin, and ceftriaxone. However, the combined treatment inhibited bacterial growth to a greater extent than the individual components, allowing for reduced concentrations of antibiotics and lower doses of photosensitizers.
The study found that the combination of light and methylene blue was the most effective, reducing bacterial load by up to sixfold compared to drug use alone. Similarly, methylene blue demonstrated potent synergy with all the antibiotics tested, achieving a significant logarithmic reduction in bacterial count and reaching complete eradication of K. pneumoniae after 18 hours when combined with ciprofloxacin.
“Light acts as a kind of ‘path opener,’ making bacteria more vulnerable to antibiotics”, the scientists said. In the article, they report: “Our study indicates that pre-treating bacteria with photodynamic therapy makes them more susceptible to antibiotics and can serve as an alternative treatment for localized infections caused by resistant bacteria”.
In addition to making treatments more efficient, this technique can reduce the necessary antibiotic dosage, which would minimize side effects and slow the development of bacterial resistance. The World Health Organization (WHO) has classified bacterial resistance as one of the main global threats to public health and development.
Hospital superbugs
The so-called superbugs are microorganisms that have developed resistance to various types of antibiotics, making infection treatment much more difficult. This resistance largely stems from the misuse of antibiotics, such as taking them without a prescription, stopping before the recommended time, or using them to treat viral diseases like colds and the flu.
The problem can worsen in debilitated hospital patients who require invasive procedures, such as catheters, tubes, and mechanical ventilation. These procedures serve as entry points for microorganisms. Hospital environments with inadequate cleaning and failures in infection control also favor the spread of superbugs.
Prevention is the main way to combat superbugs. This includes simple and effective measures, such as:
- Regularly washing hands with soap and water or using hand sanitizer;
- Using antibiotics only with a medical prescription and correctly following the indicated time and dosage;
- Avoiding the unnecessary use of antibiotics for mild or viral infections;
- Ensuring good cleaning and disinfection practices in hospitals and clinics;
- Isolating infected patients, when necessary, to prevent transmission.
Researchers believe that the combination of light and antibiotics may be applied in the future to localized infections, such as wounds, ulcers, and respiratory infections. Since it already employs substances and equipment used in clinical settings, the proposal has the potential to quickly reach medical practice.
“It is an intelligent way to reuse safe and well-known technologies to tackle one of the biggest challenges in public health”, Vanderlei Bagnato said. The study, published in the journal Antibiotics, emphasizes the importance of innovation in combined therapy use and suggests a path toward more effective, less antibiotic-dependent treatments.
The article Enhancing Antibiotic Effect by Photodynamic: The Case of Klebsiella pneumoniae is available at this link.
*By Rui Sintra, from the IFSC Communications Office. Edited by Tabita Said
English version: Nexus Traduções, edited by Denis Pacheco
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A reprodução de matérias e fotografias é livre mediante a citação do Jornal da USP e do autor. No caso dos arquivos de áudio, deverão constar dos créditos a Rádio USP e, em sendo explicitados, os autores. Para uso de arquivos de vídeo, esses créditos deverão mencionar a TV USP e, caso estejam explicitados, os autores. Fotos devem ser creditadas como USP Imagens e o nome do fotógrafo.