JAC Advance Access originally published online on September 16, 2009
Journal of Antimicrobial Chemotherapy 2009 64(5):973-985; doi:10.1093/jac/dkp320
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Original research |
Exposure of Escherichia coli and Salmonella enterica serovar Typhimurium to triclosan induces a species-specific response, including drug detoxification
1 Antimicrobial Agents Research Group, School of Immunity and Infection, The Medical School, The University of Birmingham, Birmingham B15 2TT, UK 2 School of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK 3 Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK 4 Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
Received 25 June 2009; returned 29 July 2009; revised 4 August 2009; accepted 5 August 2009
* Corresponding author. Tel: +44-121-414-6966; Fax: +44-121-414-6815; E-mail: l.j.v.piddock{at}bham.ac.uk
Objectives: The use of triclosan within various environments has been linked to the development of multiple drug resistance (MDR) through the increased expression of efflux pumps such as AcrAB–TolC. In this work, we investigate the effect of triclosan exposure in order to ascertain the response of two species to the presence of this widely used biocide.
Methods: The transcriptomes of Salmonella enterica serovar Typhimurium SL1344 and Escherichia coli K-12 MG1655 after exposure to the MIC of triclosan (0.12 mg/L) were determined in microarray experiments. Phenotypic validation of the transcriptomic data included RT–PCR, ability to form a biofilm and motility assays.
Results: Despite important differences in the triclosan-dependent transcriptomes of the two species, increased expression of efflux pump component genes was seen in both. Increased expression of soxS was observed in Salmonella Typhimurium, however, within E. coli, decreased expression was seen. Expression of fabBAGI in Salmonella Typhimurium was decreased, whereas in E. coli expression of fabABFH was increased. Increased expression of ompR and genes within this regulon (e.g. ompC, csgD and ssrA) was seen in the transcriptome of Salmonella Typhimurium. An unexpected response of E. coli was the differential expression of genes within operons involved in iron homeostasis; these included fhu, fep and ent.
Conclusions: These data indicate that whilst a core response to triclosan exposure exists, the differential transcriptome of each species was different. This suggests that E. coli K-12 should not be considered the paradigm for the Enterobacteriaceae when exploring the effects of antimicrobial agents.
Keywords: biocide , transcriptome , efflux
Present address: Fios Genomics Ltd, ETTC, King's Buildings, Edinburgh EH9 3JL, UK.
Present address: Infection Prevention Team, The Chestnuts, The Royal Wolverhampton Hospitals NHS Trust, Wednesfield Road, Wolverhampton WV10 0QP, UK.
Present address: School of Biosciences, Faculty of Science, Sutton Bonington LE12 5RD, UK.
¶ Present address: Health Protection Agency, Centre for Infections, 61 Colindale Avenue, London NW9 5EQ, UK.