Overexpression of marA, soxS and acrB in veterinary isolates of Salmonella enterica rarely correlates with cyclohexane tolerance

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Colleges, School and Institutes


Objectives: To determine the contribution of the AcrAB efflux system to cyclohexane tolerance in Salmonella enterica. Methods: The expression of the efflux pump gene, acrB, and regulators marA and soxS from 46 isolates of S. enterica of 14 different serovars was determined by comparative RT-PCR and denaturing HPLC analysis. Results: Twenty-one of the 46 isolates were cyclohexane tolerant, a phenotype associated with multiple antibiotic resistance (MAR) and overexpression of efflux pumps. Of the cyclohexane-tolerant isolates 81% were MAR, whereas only 44% of the cyclohexane-susceptible isolates were MAR, confirming the association between cyclohexane tolerance and MAR. However, there was no correlation between cyclohexane tolerance or MAR and overexpression of acrB, soxS or marA. Conclusions: These data suggest that cyclohexane tolerance in S. enterica can be mediated by an acrB-independent mechanism.


Original languageEnglish
Pages (from-to)673-9
Number of pages7
JournalJournal of Antimicrobial Chemotherapy
Issue number4
Early online date21 Feb 2006
Publication statusPublished - Apr 2006


  • Animals, Animals, Domestic, Anti-Bacterial Agents, Bacterial Proteins, Carrier Proteins, Cyclohexanes, DNA-Binding Proteins, Drug Resistance, Multiple, Bacterial, Escherichia coli Proteins, Membrane Transport Proteins, Microbial Sensitivity Tests, Salmonella enterica, Solvents, Trans-Activators