The Thai Journal of Veterinary Medicine


Bacterial antibiotic resistance is a growing problem with a global dimension. While the mechanisms of resistance vary from agent to agent, most of them are agent specific, providing resistance to a single or a class of anitimicrobials. Multidrug efflux systems have currently emerged as a predominant cause of antimicrobial resistance across a broad spectrum of structurally - unrelated antimicrobials. Efflux-mediated resistance is promoted by the exclusion of agents from the systems, resulting in reduced intracellular concentration of drugs. MES occur in many Gram-positive and Gram-negative bacteria, including medically important pathogens, therefore they are of significant concern. Expression of the systems is governed by genes located on either a chromosome or a plasmid. Imprudent and often overuse of antibiotics has been demonstrated to potentiate the problem by selecting certain mutations and enriching the multidrug resistant, bacterial population. Even though MES have been intensively studied over the past 10 years, several characteristics including molecular architecture, natural function and the regulation of expression, remain largely unclear. Novel agents that are not substrates of these systems and Efflux Pump Inhibitors (EPI) are the chosen approaches for new drug development, as they improve the therapeutic performance of many antimicrobials and benefit the medical community at large. Prudent use of antimicrobials is seriously adviced.



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