Efflux antibiotic resistance

Mechanisms (1) Alteration of biocide (enzymatic inactivation) (2) Impaired uptake (3) Efflux Chromosomally mediated, but not usually relevant Applies to several biocides Not known Plasmid/Tn-mediated e.g. mercurials Less important Cationic biocides and antibiotic-resistant staphylococci... 

Aminoglycoside efflux is a significant mechanism of aminoglycoside resistance in bacteria of the genera Pseudomonas, Burkholderia, and Stenotrophomonas. There are five classes of transmembrane efflux systems associated with antibiotic resistance however, the resistance nodulation division (RND) family is the predominant class (Table 3.1). ... 

H Nikaido. Antibiotic resistance caused by gram-negative multidrug efflux pumps. Clin Infect Dis 27 Suppl 1 32 11, 1998. 

Clearly, efflux is a major mechanism of multidrug resistance and several authors [41, 42, 71] are now reconsidering reduced drug accumulation in terms of efflux rather than as cellular impermability. It is, however, pertinent to query whether efflux of biocides is of relevance in relation to the concentrations employed in practice and whether biocides are responsible for selecting antibiotic-resistant strains as has been suggested. Clearly, much future experimentation is needed to establish a direct link between antibiotic and biocide resistances. 

Antibiotic resistance can be the result of several molecular mechanisms (Table 1). Some of the most important of these mechanisms include enzyme-catalyzed antibiotic inactivation or modification, altered transport such as efflux, and others such as metabolic bypass and sequestration. Each of these mechanisms requires the synthesis of associated proteins to mediate resistance. These are often highly specialized and efficient, and frequently the corresponding genes can be acquired on mobile... 

Table 2 Selected antibiotic resistance efflux systems...

Nikaido H. Multiple antibiotic resistance and efflux. Curr. Opin. Microbiol. 1998 1 516-523. 

Efflux Not known Cationicbiocidesand antibiotic-resistant staphylococci... 

Efflux plays a significant role as a mechanism for antibiotic resistance in many important human pathogens. However, the prevalence of efflux-mediated antibiotic... 

B.H., and Storey, D.G. (2001) Multidrug efflux pumps expression patterns and contribution to antibiotic resistance in Pseudomonas aeruginosa biofilms. Antimicrobial Agents and Chemotherapy, 45 (6), 1761-1770. 

Chevalier, J., Bredin, J., Mahamoud, A., Mallea, M., Barbe, J., and Pages, J.M. (2004) Inhibitors of antibiotic efflux in resistant Enterobacter aerogenes and Klebsiella pneumoniae strains. Antimicrobial Agents and Chemotherapy, 48 (3), 1043-1046. 

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