Methoxy‐Substituted Hydroxychalcone Reduces Biofilm Production, Adhesion and Surface Motility of Acinetobacter baumannii by Inhibiting ompA Gene Expression

Abstract

An increasing lack of available therapeutic options against Acinetobacter baumannii urged researchers to seek alternative ways to fight this extremely resistant nosocomial pathogen. Targeting its virulence appears to be a promising strategy, as it offers considerably reduced selection of resistant mutants. In this study, we tested antibiofilm potential of four synthetic chalcone derivatives against A. baumannii. Compound that showed the greatest activity was selected for further evaluation of its antivirulence properties. Real-time PCR was used to evaluate mRNA expression of biofilm-associated virulence factor genes (ompA, bap, abaI) in treated A. baumannii strains. Also, we examined virulence properties related to the expression of these genes, such as fibronectin-and collagen-mediated adhesion, surface motility, and quorum-sensing activity. The results revealed that the expression of all tested genes is downregulated together with the reduction of adhesion and motility. The conclusion is that 2'-hydroxy-2-methoxychalcone exhibits antivirulence activity against A. baumannii by inhibiting the expression of ompA and bap genes, which is reflected in reduced biofilm formation, adhesion, and surface motility.

In vitro and in silico assessment of anti-biofilm and anti-quorum sensing properties of 2,4-Di-tert butylphenol against Acinetobacter baumannii

“…In line with our results, Ušjak et al . [73] showed that A. baumannii cells after treatment with 2′-hydroxy-2-methoxychalcone, a secondary metabolite, showed a decline in mRNA levels of the bap and ompA genes at concentrations of 70 and 35 µg ml −1 , respectively. Their report further suggested that decreased expression of bap and ompA led to a decrease in surface motility and adherence-related virulence properties.…”

Auranofin promotes antibacterial effect of doripenem against carbapenem-resistant Acinetobacter baumannii

“…According to the report of Selvaraj et al, the expression of csuA/B and bfmR is associated with the surface motility of A. baumannii (Selvaraj et al, 2020). Although the role of motility in A. baumannii virulence is not fully established, many studies have reported that motility contributes to increased virulence (Blaschke et al, 2021; Eijkelkamp et al, 2013; Usjak et al, 2021). Therefore, we further investigated the effect of auranofin on A. baumannii motility and found that auranofin significantly inhibited motility (Figure 5).…”

Evaluation of novel compounds as anti-bacterial or anti-virulence agents

“…The bacterial inoculum is then added and incubated under appropriate bacterial growth conditions with bound ECM proteins for a short period of time until binding is complete (~1-4 h). Finally, the excess of unbound bacteria is washed off with PBS and quantification is performed either by staining the bacteria and following colorimetric or microscopic evaluation or by serial plating following the Triton X-100 mediated detachment ( Smani et al., 2012 ; de Oliveira et al., 2016 ; Ušjak et al., 2021 ).…”