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

Abstract

BackgroundDiclofenac 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) S. aureus strains.MethodsTranscriptional alterations in response to growth with diclofenac were measured using S. aureus gene expression microarrays and quantitative real-time PCR. Antimicrobial susceptibility was determined by agar diffusion MICs and gradient plate analysis. Ciprofloxacin accumulation was measured by fluorescence spectrophotometry.ResultsGrowth of S. aureus strain COL with 80 μg/ml (0.2 × MIC) of diclofenac resulted in the significant alteration by ≥2-fold of 458 genes. These represented genes encoding proteins for transport and binding, protein and DNA synthesis, and the cell envelope. Notable alterations included the strong down-regulation of antimicrobial efflux pumps including mepRAB and a putative emrAB/qacA-family pump. Diclofenac up-regulated sigB (σB), encoding an alternative sigma factor which has been shown to be important for antimicrobial resistance. Staphylococcus aureus microarray metadatabase (SAMMD) analysis further revealed that 46% of genes differentially-expressed with diclofenac are also σB-regulated. Diclofenac altered S. aureus susceptibility to multiple antibiotics in a strain-dependent manner. Susceptibility increased for ciprofloxacin, ofloxacin and norfloxacin, decreased for oxacillin and vancomycin, and did not change for tetracycline or chloramphenicol. Mutation to DcRS did not affect susceptibility to the above antibiotics. Reduced ciprofloxacin MICs with diclofenac in strain BB255, were not associated with increased drug accumulation.ConclusionsThe results of this study suggest that diclofenac influences antibiotic susceptibility in S. aureus, in part, by altering the expression of regulatory and structural genes associated with cell wall biosynthesis/turnover and transport.

Adaptive and Mutational Resistance: Role of Porins and Efflux Pumps in Drug Resistance

“…An alternative way of inhibiting pumps is by modulating their expression. For instance, the nonsteroidal anti-inflammatory drug (NSAID) diclofenac led to a downregulation of efflux systems in S. aureus and decreased resistance to fluoroquinolones but not to other antibiotics (210). Conversely, an antisense phosphorothioate oligodeoxynucleotide against OprM (257) led to the repression of the transcription of the oprM gene and increased antibiotic susceptibility.…”

Comparison of Gene Expression Profiles of Uropathogenic Escherichia Coli CFT073 after Prolonged Exposure to Subinhibitory Concentrations of Different Biocides

“…Many studies have shown how the transcriptome of various pathogens becomes altered after treatment with low concentrations of biocides [12,[23][24][25][26][27][28]. However, most of these studies investigated short-term response to sublethal or subinhibitory concentrations of biocides.…”

In silico validation of the non‐antibiotic drugs acetaminophen and ibuprofen as antibacterial agents against red complex pathogens

“…Most of the in vitro studies dealt so far have confirmed the antibacterial activity of APAP and IB, but only a very few studies have demonstrated the molecular mechanisms related to antimicrobial activity of these drugs . ‒ Mechanisms observed generally are inhibition of bacterial DNA replication, damage to cell membrane, activity against plasmids, downregulation of efflux pumps, reduced biofilm formation …”