Abstract: Jiang Li, Liu Qian, Zhang Xincui, Gong Chunyan Department of Pharmacy, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing 210042, China （Jiang L, Gong CY）; Department of Integrated Traditional Chinese and Western Medicine, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing 210042, China（Liu Q, Zhang XC） Corresponding author: Gong Chunyan, Email: 13057687408@163.com 【Abstract】 Objective To evaluate the in vitro antibacterial activity of 12 antibacterial agents against clinically isolated Propionibacterium acnes （P.acnes）. Methods Totally, 100 strains of P.acnes were clinically isolated from Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College between August 2014 and April 2016. A broth dilution method was used to investigate the sensitivity rate of P.acnes isolates to 12 antibacterial agents including tetracycline, doxycycline, minocycline, erythromycin, roxithromycin, clarithromycin, azithromycin, trimethoprim, levofloxacin, chloramphenicol, clindamycin and fusidic acid, and determine the minimal inhibitory concentration （MIC） of the 12 antibacterial agents against P.acnes isolates. Results The MIC90 values of minocycline, doxycycline, levofloxacin, chloramphenicol, clindamycin, fusidic acid and tetracycline against P.acnes were 8, 32, 16, 128, > 128, 16 and > 128 mg/L, respectively, and the sensitivity rates of P.acnes to the 7 antibacterial agents were 66%, 36%, 34%, 17%, 7%, 6% and 4% respectively. Trimethoprim and azithromycin showed the MIC90 value of > 128 mg/L and sensitivity rate of 3%. Erythromycin, roxithromycin and clarithromycin showed the MIC90 value of > 128 mg/L and sensitivity rate of 0. Conclusion The clinically isolated P.acnes strains showed the highest sensitivity to minocycline, followed by doxycycline, levofloxacin, chloramphenicol, clindamycin, fusidic acid, tetracycline, trimethoprim and azithromycin, and were resistant to erythromycin, roxithromycin, and clarithromycin.

Key words: Propionibacterium acnes, Anti-bacterial agents, Microbial sensitivity tests