E-GEOD-39343 - Gene expression of triclosan susceptible and tolerant E. coli O157:H19 in response to triclosan exposure
Released on 15 October 2013, last updated on 22 October 2013
Escherichia coli O157:H7
Triclosan is a biocidal active agent commonly found in domestic cleaning products, hand sanitizers, cosmetics and personal care products. It is used to control microbial contamination and has a broad-spectrum of activity against many Gram-positive and Gram-negative bacteria. The development of triclosan tolerance with potential cross resistance to clinically relevant antibiotics in zoonotic pathogens is of concern given the widespread use of this active agent in clinical, food processing and domestic environments. Some studies have proposed that an over-dependence on triclosan-containing products could lead to the emergence of clinically important pathogens that are highly tolerant to both biocides and antibiotics. Currently, there is limited understanding of the mechanisms contributing to the emergence of triclosan tolerance in foodborne pathogens at a genetic level. We used microarray analysis to compare gene expression between a wildtype E. coli O157:H19 isolate (WT) with a minimum inhibitory concentration (MIC) to triclosan of 6.25 ug/ml and its laboratory generated triclosan tolerant mutant (M) with a MIC of >8000 ug/ml. Gene expression profiling was performed on untreated E. coli O157:H19 wildtype (WTu) and mutant (Mu), and on the wildtype and mutant treated with 6 ug/ml triclosan for 30 minutes (WTt and Mt respectively). RNA was extracted from three independent biological replicates for WTu, Mu, WTt & Mt for hybridization on Affymetrix GeneChip E. coli Genome 2.0 Arrays. Micorarray analysis including pre-processing, normalisation and statistical analysis were performed using R (R, 2007) version 2.6 and Bioconductor (Gentleman et al. 2004, Genome Biol. 5:R80) version 2.1 as previously described by Morris et al.(2009, Physiol. Genomics 39:28-37).
transcription profiling by array
Mary Lenahan <email@example.com>, Aine Sheridan, Catherine Burgess, Dermot Morris, Geraldine Duffy, Seamus Fanning