Alhagi maurorum extract modulates quorum sensing genes and biofilm formation in Proteus mirabilis

Abstract

Proteus mirabilis (P. mirabilis) is a frequent cause of catheter-associated urinary tract infections. This study aims to investigate the anti-infective effect of Alhagi maurorum extract (AME), the traditional medicinal plant in the middle east, on the biofilm-forming P. mirabilis isolates. Hydroalcoholic extract and oil of A. maurorum were characterized by HPLC and GC–MS. The antiproliferative, anti-biofilm, and bactericidal activity of AME at various concentrations were assessed by turbidity, crystal violet binding, and agar well diffusion assays, respectively. The AME’s effect on adhesion and quorum sensing (QS) were investigated by in vitro adhesion assay on cell culture and agar overlay assay using Janthinobacterium lividum (ATCC 12472) as a biosensor strain. In addition, the expression level of selected genes involved in QS and biofilm regulation were determined by quantitative Real-Time PCR. Furthermore, the bladder phantom model was created to evaluate the assays and investigate the catheter’s calcium deposition. The most effective chemical compounds found in AME were tamarixetin, quercetin, and trans-anethole. Although AME did not inhibit swarming motility, it reduced biofilm production and exerted a concentration-dependent anti-adhesive and anti-QS activity against P. mirabilis. AME also downregulated the expression level of selected genes involved in biofilm formation and QS. This study showed that AME as a natural compound reduced biofilm formation of P. mirabilis by targeting virulence factor genes, quorum sensing, and other strategies that include preventing the adhesion of P. mirabilis to the cells. The results suggest that A. maurorum extract might have the potential to be considered for preventing UTIs caused by P. mirabilis.

Antibacterial, Antibiofilm, Antiswarming, and Antioxidant Activities of Flavonoids Isolated from Allium colchicifolium Leaves

“…Besides, the presence of glycoside groups attached at position 3, such as compound 4, increases the efectiveness of favonoids against bacteria compared to their aglycone form (compound 1) [66,67]. Also, compound 5 had the most signifcant efect on preventing bioflm formation by P. mirabilis, which is confrmed by the results of other studies [68].…”

“…Te antibacterial activity of the crude extract and isolated favonoids was assayed by the minimum inhibitory concentration (MIC) values using the broth microdilution method with 96-well microtiter plates according to Mirzaei et al [34]. Two-fold serial dilutions of the samples (500, 250, 125, 62.5, 31.25, 15.62, 7.81, 3.9, and 1.9 μg/ml) were prepared in 1 ml TSB.…”

“…Te inoculum of the strains was prepared in TSB-containing glucose (1% w/v) (Himedia, India), and the turbidity was adjusted to 0.5 McFarland and 1/1000 diluted to obtain fnal turbidity, approximately 0.5 × 10 5 colony-forming units (CFU)/ml. 75 μl of the solution of the compounds and 75 μl of the bacterial inoculum were inserted into the wells of a microtiter plate and incubated at 37 °C for 24 h. Te results of MIC were visually assayed, and the minimum concentration of bacteria growth was reported as MIC [34]. To fnd the exact dilution for MIC 50 , an ELISA microplate reader evaluated the bacterial growth at 595 nm.…”

“…For antiswarming efects, various concentrations of the crude extract and isolated favonoids ((500, 250, 125, 62.5, 31.25, 15.62, 7.81, 3.9, and 1.9 μg/ml) were mixed with 10 ml of the LB agar medium containing overnight cultures of P. mirabilis. After incubating the plates at 37 °C for 3 days, the inhibition of swarming activities was recorded by measuring the area of the colonies in mm [34,36].…”