Alterations in the transcriptome and antibiotic susceptibility of Staphylococcus aureus grown in the presence of diclofenac

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) which has been shown to increase the susceptibility of various bacteria to antimicrobials and demonstrated to have broad antimicrobial activity. This study describes transcriptome alterations in S. aureus strain COL grown with diclofenac and characterizes the effects of this NSAID on antibiotic susceptibility in laboratory, clinical and diclofenac reduced-susceptibility (DcRS) mutant S. aureus strains. Four hybridizations, including a biological replicate and a dye-swap experiment for each replicate was carried out. LOWESS normalization was performed on the raw data to correct for dye-bias. Statistical analysis was performed using a significance analysis of microarrays (SAM, MultiExperiment Viewer, ver. 4.0) unpaired contrast. A d-statistic was calculated for each gene based on repeated permutations, and a false discovery rate FDR of 0.01 was used to assign a critical cutoff for significance.