LAUSR

BACKGROUND AND AIM Antimicrobial photodynamic therapy (aPDT) has received considerable attention as an emerging and promising approach for treating superficial infections. The aim of this study was to investigate aPDT mediated by aloe emodin (AE), a natural compound isolated from Aloe vera and Rheum palmatum, against multidrug-resistant (MDR) Acinetobacter baumannii clinical isolates in vitro. METHODS The photodynamic inactivation (PDI) efficacies of AE on three MDR A. baumannii isolates were assessed by colony forming units (CFU) assay. The aPDT effects mediated by AE on the genomic DNA, membrane integrity, and cellular structure of MDR A. baumannii were also investigated. RESULTS AE showed no obvious dark toxicity, but inactivated the MDR A. baumannii isolates in an AE concentration and light energy dose-dependent manner. Agarose gel electrophoresis and LIVE/DEAD BacLight Bacterial Viability kit assay indicated that the genomic DNA and membrane integrity of MDR A. baumannii were damaged after AE-mediated aPDT treatment. Transmission electron microscopy (TEM) images demonstrated that AE-mediated aPDT could induce rupture of bacterial cell wall and membrane, and condensation of ribosomes in the cytoplasm. CONCLUSIONS The results obtained in this study suggested that AE could serve as a potential antibacterial photosensitizer in the treatment of superficial infections caused by MDR A. baumannii.