Biology subjects

Givskov, M.

Publications and source records attributed to Givskov, M..

4 recordsLinked to original sources

bioRxiv2017

Auranofin inhibits virulence in Pseudomonas aeruginosa

Pseudomonas aeruginosa is widely attributed as the leading cause of hospital-acquired infections. Due to intrinsic antibiotic resistance mechanisms and the ability to form biofilms, P. aeruginosa infections are challenging to treat. P. aeruginosa employs multiple virulence mechanisms to establish infections, many of which are controlled by the global virulence regulator Vfr. An attractive strategy to combat P. aeruginosa infections is thus the use of anti-virulence compounds. Here, we report the discovery that FDA-approved drug auranofin attenuates virulence in P. aeruginosa. We demonstrate that auranofin acts by targeting Vfr, which in turn leads to inhibition of quorum sensing (QS) and Type IV pili (TFP). Consistent with inhibition of QS and TFP expression, we show that auranofin attenuates biofilm maturation, and when used in combination with colistin, displays strong synergy in eradicating P. aeruginosa biofilms. Auranofin may have immediate applications as an anti-virulence drug against P. aeruginosa infections.

microbiology↗

bioRxiv2017

Synergy of Quorum Quenching Enzyme and Quorum Sensing Inhibitor in Inhibiting P. aeruginosa Quorum Sensing

The threat of antibiotic resistant bacteria has called for alternative antimicrobial strategies that would mitigate the increase of classical resistance mechanism. Many bacteria employ quorum sensing (QS) to govern the production of virulence genes and formation of drug-resistance biofilms. Blocking QS mechanisms have proven to be a functional alternative to conventional antibiotic control of infections. The concepts of quorum sensing inhibitors (QSI) and quorum quenching enzymes (QQ) have been investigated separately. In this study however, we simulated the synergistic effect of QQ and QSI in blocking bacterial QS. This effect was validated by experiments using AiiA and G1 as QQ and QSI respectively on Pseudomonas aeruginosa LasR/I and RhlR/I QS circuits. The combination of a QQ and a QSI almost completely blocked the P. aeruginosa QS las and rhl system. Our findings provided a potential application strategy for bacterial QS disruption.

microbiology↗

bioRxiv2017

The Acquisition of Resistance to Carbapenem and Macrolide-mediated Quorum Sensing Inhibition by Pseudomonas aeruginosa via a Novel Integrative and Conjugative Element ICETn43716385

Pseudomonas aeruginosa can cause persistant and life-threatening infections in immunocompromised patients. Carbapenems are the first-line agents to treat P. aeruginosa infections; therefore, the emergence of carbapenem-resistant P. aeruginosa strains has greatly challenged effective antibiotic therapy. In this study, we characterised the full-length genomes of two carbapenem resistant P. aeruginosa clinical isolates that produce the carbapebemase New Delhi metallo-{beta}-lactamase-1 (NDM-1). We found that the blaNDM-1 gene is encoded by a novel intergrative and conjugative element (ICE) ICETn43716385, which also carries the macrolide resistance gene msr(E) and the florfenicol resistance gene floR. The msr(E) gene has rarely been described in P. aeruginosa genomes. To investigate the functional roles of msr(E) in P. aeruginosa, we exogeneously expressed this gene in P. aeruginosa laboratory strains and found that the acquisition of msr(E) could abolish the azithromycin-mediated quorum sensing inhibition in vitro and the anti-Pseudomonas effect of azithromycin in vivo. In addition, the expression of msr(E) almost completely restored the azithromycin-affected P. aeruginosa transcriptome, as shown by our RNA sequencing analysis. We present the first evidence of blaNDM-1 to be carried by intergrative and conjugative elements, and the first evidence of co-transfer of carbapenem resistance and the resistance to macrolide-mediated quorum sensing inhibition into P. aeruginosa genomes.\n\nImportanceCarbapenem resistant P. aeruginosa has recently been listed as the top three most dangerous superbugs by World Health Organisation. The transmission of blaNDM-1 gene into P. aeruginosa can cause extreme resistance to carbapenems and fourth generation cephalosporins, which greatly compromises the effectiveness of these antibiotics against Pseudomonas infections. However, the lack of complete genome sequence of NDM-1-producing P. aeruginosa has limited our understanding of the transmisibility of blaNDM-1 in this organism. Here we showed the co-transfer of blaNDM-1 and msr(E) into P. aeruginosa genome by a novel integrative and conjugative element (ICE). The acquisition of these two genes confers P. aeruginosa with resistance to carbapenem and macrolide-mediated quorum sensing inhibition, both of which are important treatment stretagies for P. aeruginosa infections. Our findings highlight the potential of ICEs in transmitting carbapenem resistance, and that the anti-virulence treatment of P. aeruginosa infections by macrolides can be challenged by horizontal gene transfer.

genomics↗

bioRxiv2017

Cyclic-di-GMP is required for corneal infection by Pseudomonas aeruginosa and modulates host immunity

Biofilms are extremely tolerant toward antimicrobial treatment and host immune clearance due to their distinct physiology and protection by extracellular polymeric substances. Bis-(3{acute}-5{acute})-cyclic dimeric guanosine monophosphate (c-di-GMP) is an essential messenger that regulates biofilm formation by a wide range of bacteria. However, there is a lack of physiological characterization of biofilms in vivo as well as the roles of c-di-GMP signaling in mediating host-biofilm interactions. Here, we employed dual RNA-Seq to characterize the host and pathogen transcriptomes during Pseudomonas aeruginosa infection using a mouse keratitis model. In vivo P. aeruginosa biofilms maintained a distinct physiology compared with in vitro P. aeruginosa biofilms, with enhanced virulence and iron uptake capacity. C-di-GMP synthesis was enhanced in P. aeruginosa cells in vivo, potentially due to down-regulation of the expression of several phosphodiesterases (e.g., DipA, NbdA). Increased intracellular c-di-GMP levels were required for long-term ocular colonization of P. aeruginosa and impaired host innate immunity.

microbiology↗