Molecular characterisation of csgA gene among ESBL strains of A. baumannii and targeting with essential oil compounds from Azadirachta indica

摘要

ObjectivesA. baumanniiis considered as a “red alert” nosocomial human pathogen and exhibits an extensive antibiotic resistance spectrum. The biofilm formation mediated by thecsgAis a potent virulence factor inA. baumanniiand targeting the same would be of a novel strategy to controlA. baumanniiinfections. The aim of the present study is thus to evaluate the anti-biofilm activity of essential bio-compounds fromAzadirachta indicaagainst the ESBL producing strains ofA. baumanniibyin-vitroandin-silicostudies.MethodsBiofilm formation by Semi-quantitative adherence assay was performed for the 73 strains of ESBL producingA. baumannii. Genomic DNA was extracted and molecular characterization ofcsgAgene was done by PCR amplification with further sequencing.In-vitroanti biofilm assay from crude extract ofA.indicawas performed which was then followed by thein-silicodocking involving retrieval of csgA protein and ligand optimisation, molinspiration assessment on drug likeliness, docking simulations and visualisations.ResultsBiofilm assay showed 58.9%, 31.5% and 0.09% as high grade, low grade and non-biofilm formers respectively. 20.54% (15/73) of the screened genomes showed positive amplicons for thecsgAgene associated with biofilm formation among the ESBL producing strains ofA. baumannii. All the ceftazidime, cefipime and cefotaxime resistant strains showed the presence ofcsgAgene (100%; 15/15), followed by 46.6% (7/15) resistant isolates for ceftriaxone.In-vitrocrystal violet viability assay showed MBEC50and MBEC90at a concentration of 20?μl and 40?μl respectively.In-silicoassessments on the essential oil compounds from neem showed imidazole to exhibit the highest interaction with least docking energy and high number of hydrogen bonds.ConclusionThe current study emphasises thatimidazole fromA.indicato be a promising candidate for targeting thecsgAmediated biofilm formation in ESBL strains ofA. baumannii. However, furtherin-vivostudies have to be implemented for the experimental validation of the same.