Objectives

A. baumannii is considered as a “red alert” nosocomial human pathogen and exhibits an extensive antibiotic resistance spectrum. The biofilm formation mediated by the csgA is a potent virulence factor in A. baumannii and targeting the same would be of a novel strategy to control A. baumannii infections. The aim of the present study is thus to evaluate the anti-biofilm activity of essential bio-compounds from Azadirachta indica against the ESBL producing strains of A. baumannii by in-vitro and in-silico studies.

Methods

Biofilm formation by Semi-quantitative adherence assay was performed for the 73 strains of ESBL producing A. baumannii. Genomic DNA was extracted and molecular characterization of csgA gene was done by PCR amplification with further sequencing. In-vitro anti biofilm assay from crude extract of A.indica was performed which was then followed by the in-silico docking involving retrieval of csgA protein and ligand optimisation, molinspiration assessment on drug likeliness, docking simulations and visualisations.

Results

Biofilm 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 the csgA gene associated with biofilm formation among the ESBL producing strains of A. baumannii. All the ceftazidime, cefipime and cefotaxime resistant strains showed the presence of csgA gene (100%; 15/15), followed by 46.6% (7/15) resistant isolates for ceftriaxone. In-vitro crystal violet viability assay showed MBEC₅₀ and MBEC₉₀ at a concentration of 20 µl and 40 µl respectively. In-silico assessments on the essential oil compounds from neem showed imidazole to exhibit the highest interaction with least docking energy and high number of hydrogen bonds.

Conclusion

The current study emphasises that imidazole from A.indica to be a promising candidate for targeting the csgA mediated biofilm formation in ESBL strains of A. baumannii. However, further in-vivo studies have to be implemented for the experimental validation of the same.

中文翻译：

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鲍曼不动杆菌ESBL菌株中csgA基因的分子表征并以印度印za（Azadirachta indica）的精油为靶标

目标

鲍曼不动杆菌被认为是“红色警戒”的医院内人类病原体，具有广泛的抗生素耐药性谱。由csgA介导的生物膜形成是鲍曼不动杆菌中的一种强毒力因子，靶向该生物膜将是控制鲍曼不动杆菌感染的一种新策略。因此，本研究的目的是通过体外和计算机模拟研究来评价印度印za必不可少的生物化合物对产ESBL鲍曼不动杆菌的抗生物膜活性。

方法

通过半定量粘附试验对73株产ESBL的鲍曼不动杆菌进行生物膜形成。提取基因组DNA，并通过PCR扩增和进一步测序完成csgA基因的分子表征。进行了印度ind草粗提取物的体外抗生物膜测定，然后进行了计算机对接，包括对csgA蛋白和配体的优化检索，对药物相似性的运动性评估，对接模拟和可视化。

结果

生物膜检测结果分别为高，低和非生物膜形成者，分别为58.9％，31​​.5％和0.09％。筛选的基因组中有20.54％（15/73）显示与产ESBL的鲍曼不动杆菌菌株中与生物膜形成相关的csgA基因的阳性扩增子。所有对头孢他啶，头孢吡肟和头孢噻肟耐药的菌株均显示存在csgA基因（100％； 15/15），其次是对头孢曲松的耐药菌株为46.6％（7/15）。体外结晶紫生存力测定表明，MBEC ₅₀和MBEC ₉₀的浓度分别为20 µl和40 µl。硅内 对印ne的精油化合物的评估表明，咪唑显示出最高的相互作用，对接能最少，氢键数量很多。

结论

目前的研究强调，来自印度拟南芥的咪唑是靶向鲍曼不动杆菌ESBL菌株中由csgA介导的生物膜形成的有前途的候选者。但是，必须进行进一步的体内研究以对其进行实验验证。