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Volume 51, Number 1, February 2018

In vitro and in vivo antibacterial activity of tigecycline against Vibrio vulnificus 


Hung-Jen Tang, Chi-Chung Chen, Chih-Cheng Lai, Chun-Cheng Zhang, Tzu-Chieh Weng, Yu-Hsin Chiu, Han-Siong Toh, Shyh-Ren Chiang, Wen-Liang Yu, Wen-Chien Ko, Yin-Ching Chuang


 

Corresponding author:

Wen-Chien Ko, Corresponding author. Department of Internal Medicine, National Cheng Kung University Hospital, Number 138, Sheng Li Road, 704 Tainan, Taiwan. 



 

Background and purpose: 

The aim of this study is to investigate the role of tigecycline in Vibrio vulnificus infection.

 



 

Methods:

Eight randomly selected clinical V. vulnificus isolates were studied to obtain the minimal inhibitory concentrations (MICs) of minocycline, cefotaxime, and tigecycline, and the time–kill curves of tigecycline alone or in combination with other drugs. A peritonitis mouse model was used for the evaluation of the therapeutic efficacy of tigecycline alone or cefotaxime in combination with minocycline or tigecycline. 



 

Results:

The MIC of minocycline, cefotaxime, and tigecycline for eight clinical V. vulnificus isolates was 0.06–0.12 μg/mL, 0.03–0.06 μg/mL, and 0.03–0.06 μg/mL, respectively. In time–killing studies, at the concentration of 1 × MIC, the inhibitory effect of tigecycline persisted for 24 hours in five of eight isolates. With 2 × MIC and trough level, the inhibitory effect was noted in all isolates for 24 hours. With the combination of minocycline plus cefotaxime and tigecycline plus cefotaxime at 1/2 × MIC, the bactericidal effect was noted in 25% and 62.5% of eight isolates and synergism in 50% and 75% of isolates. With a low (1.25 × 105 CFU/mL) inoculum, all infected mice survived with tigecycline alone, tigecycline plus cefotaxime, or minocycline plus cefotaxime on the 14th day. At the inoculum of 1.25 × 106 CFU, the survival rate was 33.3% on the 14th day in the tigecycline plus cefotaxime-treated group, but none of the mice treated by tigecycline alone or minocycline plus cefotaxime survived (33.3% vs. 0%, p = 0.01 by Fisher's exact test). 



 

Conclusion:

Our in vitro combination and animal studies indicate that tigecycline could be an option for the treatment of invasive V. vulnificus infections. 



 

Key words:

killing effects, tigecycline, Vibrio vulnificus