Assessment of toxicity, anti-quorum sensing and anti-biofilm production effects of Hypericum triquetrifolium Turra extract on multi-drug resistant Acinetobacter baumannii

Abstract

Acinetobacter baumannii is a multidrug-resistant and an invasive bacterium and a significant contributor to nosocomial infections in the present healthcare system. It’s striking capability to survive in hospital settings on medical equipments is due to its capability of quorum sensing and biofilm formation. New medications and formulations to combat this pathogen is the need of this hour. Hypericum triquetrifolium Turra, a less famous medicinal plant is known for its antibacterial characteristics. However, there is hardly any research articles or findings to back this claim against the Acinetobacter sp. Total of 50 bacterial isolates were collected. 98% of them were resistant to Ciprofloxacin. 4% showed strong biofilm production, while 40% and 56% of the isolates revealed weak and moderate bioflim production. Biochemical analysis revealed that the ethanolic leaves extract of H. triquetrifolium Turra contains potent phytochemical compounds. Toxicity assessment of the plant extract revealed that the extract was slightly toxic where LD50 was 4.95 g/Kg. Minimum inhibitory concetrations and Sub-minimum inhibitory concetrations of H. triquetrifolium Turra leaf extract against two strongest biofilm producers and ATCC strain of A. baumannii (19606) were estimated. MICs values were 10–15 mg/ml and SICs 5–10 mg/ml. Investigations revealed significant reductions in biofilm formation when isolates were treated with SICs of the extract. Transcription expression of quorum sensing genes, abaI/abaR, down regulated when treated with H. triquetrifolium extract. One of the Biofilm regulating genes among Bap/OmpA, were found to be sharply down regulated especially, Bap gene; however, OmpA gene didn’t show noticable change in the expression. We concluded that H. triquetrifolium Turra may have promising activity against A. baumannii in it’s quorum sensing and biofilm formation, thus it could be employed as potential as an antibacterial medication.