Hydroquinine Inhibits the Growth of Multidrug-Resistant Pseudomonas aeruginosa via the Suppression of the Arginine Deiminase Pathway Genes

Abstract

Hydroquinine has antimicrobial potential with demonstrated activity against several bacteria, including multidrug-resistant (MDR) P. aeruginosa reference strains. Despite this, there is limited evidence confirming the antibacterial activity of hydroquinine against clinical isolates and the underlying mechanism of action. Here, we aimed to investigate the antibacterial effect of hydroquinine in clinical P. aeruginosa strains using phenotypic antimicrobial susceptibility testing and synergistic testing. In addition, we examined the potential inhibitory mechanisms against MDR P. aeruginosa isolates using informatic-driven molecular docking analysis in combination with RT-qPCR. We uncovered that hydroquinine inhibits and kills clinical P. aeruginosa at 2.50 mg/mL (MIC) and 5.00 mg/mL (MBC), respectively. Hydroquinine also showed partial synergistic effects with ceftazidime against clinical MDR P. aeruginosa strains. Using SwissDock, we identified potential interactions between arginine deiminase (ADI)-pathway-related proteins and hydroquinine. Furthermore, using RT-qPCR, we found that hydroquinine directly affects the mRNA expression of arc operon. We demonstrated that the ADI-related genes, including the arginine/ornithine antiporter (arcD) and the three enzymes (arginine deiminase (arcA), ornithine transcarbamylase (arcB), and carbamate kinase (arcC)), were significantly downregulated at a half MIC of hydroquinine. This study is the first report that the ADI-related proteins are potential molecular targets for the inhibitory effect of hydroquinine against clinically isolated MDR P. aeruginosa strains.

Hydroquinine Enhances the Efficacy of Contact Lens Solutions for Inhibiting Pseudomonas aeruginosa Adhesion and Biofilm Formation

“…Our research suggests that hydroquinine suppresses P. aeruginosa fimbrial activity by impairing surface attachment and interrupting their chemotaxis, resulting in the prevention of biofilm formation. This is supported by previous research showing that hydroquinine could suppress L-arginine via the arginine deiminase pathway, resulting in decreased biofilm formation [31]. This is also consistent with a previous study by Rattanachak et al showing that hydroquinine could suppress QS-related gene expression, reduce virulence factor production, and impair biofilm formation in P. aeruginosa [32].…”

“…Hydroquinine has been shown to be effective at killing both drug-sensitive and multidrug-resistant P. aeruginosa [29,31,32]. Hydroquinine attenuates P. aeruginosa growth by reducing flagella activity, pyocyanin production, and biofilm formation [32].…”

“…4.1. P. aeruginosa Strains, Cultivation, and Inoculum Preparation P. aeruginosa ATCC 27853 was obtained from the American Type Culture Collection (ATCC; Manassas, VA, USA) and a clinical P. aeruginosa strain was isolated from an eyeinfected and hospitalized patient from a previous study [31]. The bacterial isolates were steaked on the Mueller Hinton Agar (MHA, Oxoid, Basingstoke, UK) and then incubated overnight at 35 ± 2 • C. The turbidity of inoculum was adjusted to 0.5 McFarland standard around 1-2 × 10 8 CFU/mL [29,31,32].…”

“…Furthermore, Jongjitwimol and Baldock proposed that hydroquinine has potential as an antimicrobial agent to target the MDR strains of P. aeruginosa [30]. In support of this, recent research has shown that hydroquinine showed anti-P. aeruginosa efficacy against both clinical drug-sensitive (DS) and multidrug-resistant (MDR) P. aeruginosa strains [31]. Rattanachak et al (2022) used transcriptomics approaches and identified that the levels of several key transcripts were altered in P. aeruginosa ATCC 27853 when treated with 1.25 mg/mL hydroquinine for an hour [32], because this concentration has some molecular and functional effects against P. aeruginosa without a killing effect [29].…”

Protein Citrullination by Peptidyl Arginine Deiminase/Arginine Deiminase Homologs in Members of the Human Microbiota and Its Recognition by Anti-Citrullinated Protein Antibodies

“…ADs are conserved in a variety of bacteria, and the AD pathway provides energy in anaerobic conditions. L-arginine, an essential molecule in the formation of biofilms, is catalyzed by ADs and converted into L-citrulline; subsequently, metabolic conversion steps follow, which finish with the production of ATP, ammonia, and CO 2 [47]. A recent database analysis identified homologs of PAD/AD in the phyla Cyanobacteria, Actinobacteria, and Proteobacteria [48].…”