The potential application of photodynamic therapy in drug-resistant tuberculosis

• The emergence of drug-resistant TB (DR-TB) has affected the treatment of TB.
• Chemotherapy has a limitation on DR-TB, therefore a novel treatment is required.
• Photodynamic therapy (PDT) could be a novel option to treat MDR- and XDR-TB.

Tuberculosis (TB) is an infectious bacterial disease that has historically created a high global health burden. Unfortunately, the emergence of drug-resistant TB (DR-TB), which includes multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB), has greatly affected the treatment of TB. Anti-TB chemotherapy drugs are classified into five groups to facilitate application of effective guidelines for the treatment regimen. However, chemotherapy has a limited ability to treat DR-TB, and therefore a novel alternative treatment for DR-TB is required. In this review, we focused on photodynamic therapy (PDT) as potential treatment for DR-TB. PDT is a widely used cancer treatment that combines photosensitizers and harmless laser light to produce reactive oxygen species that selectively damage the target cells. Initially, PDT was originally developed to target pathogenic microorganisms but fell into disuse because of adverse reactions. Recently, photodynamic antimicrobial chemotherapy is attracting attention again as an alternative treatment for bacterial infections. In our previous study, we suggested that PDT could be a novel option to treat MDR- and XDR-TB in vitro. Despite the limited previous studies regarding PDT in TB models, fast-developing bronchoscopic technologies and clinician experience will soon facilitate the clinical application of safe and minimally invasive PDT for TB.