Quorum quenching activity of Aerva lanata against Catheter Associated Urinary Tract Infections (CAUTI) Pathogens

Background. CAUTI is the most common hospital infection caused by Gram-negative bacterium owing to their ability to colonize UT mucosa. These uro-pathogens elaborate quorum sensing (QS) molecules that modify the expression and secretion of biofilm matrix compounds in response to rheological and other UT changes during catheterization. Quenching the biological effects of QS molecules will have substantial clinical value. This study identifies and evaluate the antibiofilm/anti-virulence properties of Aerva lanata plant extract against select CAUTI pathogens.

Methods. Methanolic extract of Aerva lanata was screened for its anti-urobacterial effects using Chromobacterium violaceum as the test strain. A. lanata extract impact on the QS molecule, acyl homoserine lactone (AHL) regulated bacterial functions essential for biofilm formation was investigated. It includes RT-PCR analysis of QS genes in the bacterium and in silico studies of bacterial compounds.

Results. Methanolic extract of A. lanata interfered with AHL regulated physiological functions such as biofilm formation, pellicle inhibition, flagellar motility and exopolysaccharides (EPS) production. In situ-visualization of biofilm with confocal microscopy showed concentration influenced reduction in bacterial biofilm formation in response to plant extract. GC-MS identified 11 compounds and molecular docking analysis predicted their respective host receptors. In silico analysis of plant extract revealed putative compounds with potential to inhibit the bacterial QS AHL system. RT-PCR analysis revealed down regulation of QS related virulence genes viz., las1, lasR, lasB, lasA.

Conclusion. Data obtained in this study strongly suggests that Aerva lanata should be further investigated for its therapeutic potentials to treat bacterial CAUTI.