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cephalosporinase, OprD porin, and efflux pumps [ 4 , 5 ]. Efflux pumps (Mex pumps) can extrude one or more antibiotics from bacterial cells into the external environment and hence are involved in intrinsic and acquired resistance as well as the emergence of
A. baumannii are efflux pumps and ribosome protection. Among tet genes, tetA , tetB , tetA(39) and tetH genes have been recognized as efflux pump genes, by which tetracycline and doxycycline are pumped out of A. baumannii . Moreover, tet
resistance to trimethoprim/sulfamethoxazole, tetracyclines, macrolides, ampicillin and chloramphenicol [ 12 ]. One of the significant mechanisms of tolerance to biocides are efflux pumps that are included in the major facilitator superfamily (MFS), the
Various bacterial plasmids can be eliminated from bacterial species cultured as pure or mixed bacterial cultures by non-mutagenic heterocyclic compounds at subinhibitory concentrations. For plasmid curing, the replication should be inhibited at three different levels simultaneously: the intracellular replication of plasmid DNA, partition and intercellular transconjugal transfer. The antiplasmid action of the compounds depends on the chemical structure. The targets for antiplasmid compounds were analysed in detail. It was found that amplified extrachromosomal DNA in the superhelical state binds more drug molecules than does the linear or open-circular form of the plasmid or the chromosome, without stereospecificity which leads to functional inactivation of the extrachromosomal genetic code. Plasmid elimination also occurs in ecosystems containing numerous bacterial species simultaneously, but the elimination of antibiotic resistance-encoding plasmids from all individual cells of the population is never complete. The medical significance of plasmid elimination in vitro is, it provides a method to isolate plasmid-free bacteria for biotechnology without any risk of mutations, and it opens up a new perspective in rational drug design against bacterial plasmids. Hypothetically, the combination of antiplasmid drugs and antibiotics may improve the effectivity of antibiotics against resistant bacteria; therefore, the results cannot be exploited until the curing efficiency reaches 100%. Inhibition of the conjugational transfer of antibiotic resistance plasmids can be exploited to reduce the spreading of these plasmids in ecosystems.
Enterococcus faecalis is one of the most significant pathogen in both nosocomial and community-acquired infections. Reduced susceptibility to antibiotics is in part due to efflux pumps. This study was conducted on 80 isolates of E. faecalis isolated from outpatients with urinary tract infection during a period of 1 year from April 2014 to April 2015. The antibiotic susceptibility patterns of isolates were determined by the disk diffusion method and presence of efrA and efrB genes was detected by PCR and sequencing. Minimum inhibitory concentrations (MICs) to ciprofloxacin (CIP) were measured with and without carbonyl cyanide 3-chlorophenylhydrazone (CCCP) by broth microdilution. The highest resistance rate was observed to erythromycin (83.3%) and the prevalence of efrA and efrB genes in all E. faecalis isolates was 100%. This study showed that 9 out of 13 (69.2%) ciprofloxacin-resistant isolates became less resistant at least fourfolds to CIP in the presence of efflux pump inhibitor. Our result showed that CCCP as an efflux inhibitor can increase effect of CIP as an efficient antibiotic and it is suggested that efrAB efflux pumps are involved in resistance to fluoroquinolone.
efflux pump has been described in A. baumannii . It is a putative major facilitator superfamily (MFS) transporter, which is encoded by abaQ gene. This efflux pump is the first to mediate quinolone resistance among A. baumannii isolates. Moreover, it
effective therapeutic alternatives available [ 5, 6 ]. Carbapenem resistance may develop through a variety of cellular mechanisms: alteration in membrane permeability and porin loss (e.g., ΔOmpK in Klebsiella pneumoniae ), overexpression of efflux pumps
Amaral, L., Viveiros, M., Engi, H. et al.: Comparison of multidrug resistant efflux pumps of bacteria and cancer cells with respect to the same inhibitory agents. In Vivo, 2007, 21 , 237–244. Engi H
3488 3497 Costa SS, Viveiros M, Amaral L, Couto I: Multidrug Efflux Pumps in Staphylococcus aureus : an Update. Open Microbiol J 7, 59–71 (2013
disinfectant non-susceptible bacteria frequently [ 15 , 20 ]. Resistance to disinfectants is mainly mediated by efflux pumps which expel disinfectants from bacterial cells [ 21 , 20 ]. Efflux pumps are rather unspecific and can extrude a variety of
