Alterations In the Transciptome and Antibiotic Susceptibility of \u3ci\u3eStaphylococcus aureus\u3c/i\u3e Grown In the Presence of Diclofenac

Background 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) S. aureus strains. Methods Transcriptional 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. Results Growth 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. Conclusions The 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

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

<p>Abstract</p> <p>Background</p> <p>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 <it>S. aureus </it>strain COL grown with diclofenac and characterizes the effects of this NSAID on antibiotic susceptibility in laboratory, clinical and diclofenac reduced-susceptibility (Dc^RS) <it>S. aureus </it>strains.</p> <p>Methods</p> <p>Transcriptional alterations in response to growth with diclofenac were measured using <it>S. aureus </it>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.</p> <p>Results</p> <p>Growth of <it>S. aureus </it>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 <it>mepRAB </it>and a putative <it>emrAB/qacA</it>-family pump. Diclofenac up-regulated <it>sigB </it>(σ^B), encoding an alternative sigma factor which has been shown to be important for antimicrobial resistance. <it>Staphylococcus aureus </it>microarray metadatabase (SAMMD) analysis further revealed that 46% of genes differentially-expressed with diclofenac are also σ^B-regulated. Diclofenac altered <it>S. aureus </it>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 Dc^RSdid not affect susceptibility to the above antibiotics. Reduced ciprofloxacin MICs with diclofenac in strain BB255, were not associated with increased drug accumulation.</p> <p>Conclusions</p> <p>The results of this study suggest that diclofenac influences antibiotic susceptibility in <it>S. aureus</it>, in part, by altering the expression of regulatory and structural genes associated with cell wall biosynthesis/turnover and transport.</p

Modelling and optimization of Searaser wave energy converter based hydroelectric power generation for Saint Martin's Island in Bangladesh

Saint Martin's Island is one of the most notable tourist spots and the only coral island of Bangladesh in the Bay-of-Bengal. Yet due to lack of electricity supply, this beautiful island is becoming uninhabitable and losing tourist attraction. In this study, a decentralized Mini Hydroelectric Power Plant (MHPP) has been proposed and designed to mitigate electricity demand in the tourist resorts of the island during peak demand–hours: the energy input to the plant is supplied by harnessing ocean wave-power available in the coastal regions of the island with a novel and simple Wave Energy Converter (WEC) named Searaser. To decide about the installed capacity of the proposed MHPP, a field survey was conducted on the resorts of St. Martin's Island. The performance of Searaser in the context of the island was investigated theoretically which indicated that the Searaser is capable of producing about 35 m of water-head by utilizing the available wave-power. Realizing the availability of wave-power and adopting sustainable tourism policy, the estimated plant capacity was about 144 kW. This study remarks that the implementation of Searaser based MHPP technology in the St. Martin's Island can be a profitable and eco-friendly replacement of the existing stand-alone diesel-generators; it was also found that huge amount of Greenhouse Gas (GHG) emission can be prevented, and thereby the tourism potential can be enhanced as well. © 2019 Elsevier Lt

The Fusidic Acid Timulon of \u3ci\u3eStaphylococcus aureus\u3c/i\u3e

Fusidic acid interferes with the release of elongation factor G (EF-G) after the translocation step of protein synthesis. The objective of this study was to characterize the fusidic acid stimulon of a fusidic acid-susceptible strain of Staphylococcus aureus (SH1000). S. aureus microarrays and real-time PCR determined transcriptome alterations occurring in SH1000 grown with fusidic acid. The Staphylococcus aureus microarray meta-database (SAMMD) compared and contrasted the SH1000 fusidic stimulon with 89 other S. aureus transcriptional datasets. Fusidic acid gradient analyses with mutant-parent strain pairs were used to identify genes required for intrinsic fusidic acid susceptibility identified during transcriptional analysis. Many genes altered by fusidic acid challenge are associated with protein synthesis. SAMMD analysis determined that the fusidic acid stimulon has the greatest overlap with the S. aureus cold shock and stringent responses. Six out of nine peptidoglycan hydrolase genes making up the two component YycFG regulon were also up-regulated by fusidic acid, as were a carboxylesterase gene (est) and two putative drug efflux pump genes (emr-qac1 and macA). Genes down-regulated by fusidic acid induction encoded a putative secreted acid phosphatase and a number of protease genes. Roles for the agr operon, the peptidoglycan hydrolase gene isaA and two proteases (htrA1 and htrA2) in the expression of fusidic acid susceptibility were revealed. The SH1000 fusidic acid stimulon includes genes involved with two stress responses, YycFG-regulated cell wall metabolism, drug efflux, and protein synthesis and turnover