Yingjie Shen,1 Zengyue Gu,2 Yujie Li,2 Hanmeng Zhou,2 Shengzhe Zhu,2 Lingtao Sheng,2 Xinhua Qiang,3 Xiangkuo Zheng2 

1School of Life Sciences, Huzhou University, Huzhou, 313000, People’s Republic of China; 2School of Medicine, Huzhou University; Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, Huzhou, 313000, People’s Republic of China; 3Department of Clinical Laboratory, The First Affiliated Hospital of Huzhou University, Huzhou, 313000, People’s Republic of China

Correspondence: Xiangkuo Zheng, School of Medicine, Huzhou University; Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, 759 East Second Ring Road, Wuxing District, Huzhou, 313000, People’s Republic of China, Tel +86-0572-2321531, Email kuo7436@163.com Xinhua Qiang, Department of Clinical Laboratory, The First Affiliated Hospital of Huzhou University, 158 Back Square Road, Wuxing District, Huzhou, 313000, People’s Republic of China, Tel +86-0572-2039408, Email qiangxinhua@zjhu.edu.cn

Background: Pseudomonas aeruginosa (P. aeruginosa) wound infections are an emerging global health threat. Empiric therapy of infected wounds with Chinese dragon’s blood (CDB) is one of the most precious traditional Chinese medicines used in clinical settings. We investigated the anti-virulence efficacy of CDB against P. aeruginosa isolated from wound infections.
Methods: We collected six P. aeruginosa clinical isolates obtained from wound specimens. Antimicrobial susceptibility profiles were determined using the agar dilution method. Biofilm formation and eradication assays, quantitative real-time PCR (RT-qPCR), and bacterial motility assays were performed to evaluate the efficacy of CDB on biofilm formation, mature biofilm eradication, and motility ability of P. aeruginosa isolates.
Results: Minimal inhibitory concentration (MIC) values of CDB against P. aeruginosa isolates were ≥ 1024 μg/mL. The differences in biofilm formation ability between the CDB-containing LB broth and LB broth groups were statistically significant (P < 0.05). The results of mature biofilm-eradicating assays indicated that CDB had excellent efficacy on eradicating the biofilm formed by all experimental strains (P < 0.05). The mRNA relative expression of lasR, pslA, pelA, algD, and algU genes in P. aeruginosa strains was significantly downregulated after exposure to CDB at a concentration of 128 μg/mL (P < 0.05). CDB could inhibit the motility ability of P. aeruginosa isolates through swimming, swarming, and twitching motilities.
Conclusion: CDB exerts a positive anti-virulence efficacy on P. aeruginosa. CDB significantly reduced the biofilm formation by downregulating the mRNA relative expression of the biofilm-associated genes lasR, pslA, pelA, algD, and algU. In addition, CDB efficiently inhibited the motility ability of P. aeruginosa isolates by swimming, swarming, and twitching motilities in a concentration-dependent manner. Therefore, these findings position CDB as an alternative for P. aeruginosa wound infections management in clinical settings.

Keywords: Chinese dragon’s blood, wound infections, Pseudomonas aeruginosa, anti-virulence efficacy