In vitro study of the effect of ALA-PDT on Mycobacterium abscessus and its antibiotic susceptibility

• Published in: Photodiagnosis and photodynamic therapy 2022-06, Vol.38, p.102802-102802, Article 102802
• Main Authors: Yue, Chenda, Wang, Liqun, Wang, Xiaoyu, Cen, Ruiyan, Chen, Jinyi, Li, Lingfei, Yang, Weijiang, Tan, Yang, Lei, Xia
• Format: Article
• Language: English
• Subjects: Aminolevulinic Acid - pharmacology; Anti-Bacterial Agents - pharmacology; Antibiotic susceptibility; Mycobacterium abscessus; Photochemotherapy - methods; Photodynamic therapy; Photosensitizing Agents - pharmacology
• ISSN: 1572-1000; 1873-1597
• DOI: 10.1016/j.pdpdt.2022.102802

•ALA-PDT has a significant effect on M. abscessus in planktonic and biofilm forms.•ALA-PDT can increase the antibiotic susceptibility of M. abscessus.•The killing effect of ALA-PDT relies on the damage of the cell membrane.•Lethal dose ALA-PDT alters the cell wall permeability and resistance gene expression. The skin infection caused by Mycobacterium abscessus (M. abscessus) is extremely difficult to treat in clinical practice. PDT (photodynamic therapy) is a promising antibacterial treatment. We evaluated the effect of photodynamic therapy using 5-aminolevulinic acid (ALA) as a photosensitizer on M. abscessus and its antibiotic resistance in this study. M. abscessus and biofilm were treated with different concentrations of ALA and then irradiated with LED light (635 nm, 80 J/cm2), while there were ALA-only group, light-only group, and negative control group. The effects were observed by colony counting, crystal violet staining, confocal laser scanning microscope (CLSM), and scanning electron microscope (SEM). The changes of drug susceptibility of M. abscessus at sublethal doses were detected by micro-broth dilution method, and the possible mechanism was explored by fluorometer and real-time fluorescence quantitative Polymerase Chain Reaction (RT-qPCR). ALA-PDT showed a significant killing effect on M. abscessus at ALA concentrations greater than 50 μg/ml and the effect increased with increasing photosensitizer concentrations. ALA-PDT also showed a notable scavenging effect on M. abscessus biofilm, which was also enhanced with increasing ALA concentrations. At sublethal doses, the susceptibility of M. abscessus to antibiotics was increased, and ALA-PDT greatly increased the cell wall permeability of M. abscessus and decreased the mRNA expression of drug resistance genes whiB7 and erm (41), as well as efflux pump genes MAB_1409c and MAB_3142c at the transcriptional level. ALA-PDT has a significant killing effect on M. abscessus and can increase its antibiotic susceptibility.