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J Infect Dis. 2011 Jan 15;203(2):273-82. doi: 10.1093/infdis/jiq029. Epub 2010 Dec 9.

Underlying mechanism of in vivo and in vitro activity of C-terminal-amidated thanatin against clinical isolates of extended-spectrum beta-lactamase-producing Escherichia coli.

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Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China.



Infections with extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) have developed resistance to current therapies. Therefore, the underlying mechanisms of in vivo and in vitro activity of C-terminal-amidated thanatin (A-thanatin) against clinical isolates of ESBL-EC were studied in an attempt to resolve this problem.


A-thanatin was synthesized to determine its minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and kill curve for ESBL-EC. The hemolytic toxicity, stability, and resistance induction of A-thanatin were determined. ESBL-EC-infected mice were used to determine the in vivo activity of A-thanatin. Scanning and transmission electron microscopy and fluorescence microscopy were used to study the underlying mechanism of A-thanatin.


A-thanatin is highly effective against ESBL-EC in vitro, with MIC values ≤4 μg/mL. It has been confirmed that A-thanatin has little hemolysis and relative high stability in plasma. Excellent in vivo therapeutic effects were also observed in a septicemic animal model, with survival rates of 50.0%, 66.7%, and 91.7% in the low-dose, middle-dose, and high-dose groups, respectively. Membrane permeabilization may be a major biological action of A-thanatin.


Because the development of multidrug resistance limits the available therapeutic options, A-thanatin may provide a novel strategy for treating ESBL-EC infection and other infections due to multidrug-resistant bacteria.

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