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Int. J. Mol. Sci. 2015, 16(9), 21711-21733;

The Three Bacterial Lines of Defense against Antimicrobial Agents

1,2,3,* , 1,2,3
Guangdong Institute of Microbiology, Guangzhou 510070, Guangdong, China
State Key Laboratory of Applied Microbiology Southern China, Guangzhou 510070, Guangdong, China
Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangzhou 510070, Guangdong, China
Author to whom correspondence should be addressed.
Academic Editor: Ester Boix
Received: 29 July 2015 / Revised: 21 August 2015 / Accepted: 31 August 2015 / Published: 9 September 2015
(This article belongs to the Section Biochemistry)
Full-Text   |   PDF [1761 KB, uploaded 9 September 2015]   |  


Antimicrobial agents target a range of extra- and/or intracellular loci from cytoplasmic wall to membrane, intracellular enzymes and genetic materials. Meanwhile, many resistance mechanisms employed by bacteria to counter antimicrobial agents have been found and reported in the past decades. Based on their spatially distinct sites of action and distribution of location, antimicrobial resistance mechanisms of bacteria were categorized into three groups, coined the three lines of bacterial defense in this review. The first line of defense is biofilms, which can be formed by most bacteria to overcome the action of antimicrobial agents. In addition, some other bacteria employ the second line of defense, the cell wall, cell membrane, and encased efflux pumps. When antimicrobial agents permeate the first two lines of defense and finally reach the cytoplasm, many bacteria will make use of the third line of defense, including alterations of intracellular materials and gene regulation to protect themselves from harm by bactericides. The presented three lines of defense theory will help us to understand the bacterial resistance mechanisms against antimicrobial agents and design efficient strategies to overcome these resistances. View Full-Text
Keywords: antimicrobial agents; defense lines; resistance mechanism; action sites; new theory antimicrobial agents; defense lines; resistance mechanism; action sites; new theory

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Zhou, G.; Shi, Q.-S.; Huang, X.-M.; Xie, X.-B. The Three Bacterial Lines of Defense against Antimicrobial Agents. Int. J. Mol. Sci. 2015, 16, 21711-21733.

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