Department of Medical Microbiology and Immunology, Faculty of Medicine, Assiut University, Assiut, 71515, Egypt.
Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, 45267-0595, USA.
Sci Rep. 2021 May 24;11(1):10751. doi: 10.1038/s41598-021-90208-4.
We aimed to isolate Acinetobacter baumannii (A. baumannii) from wound infections, determine their resistance and virulence profile, and assess the impact of Silver nanoparticles (AgNPs) on the bacterial growth, virulence and biofilm-related gene expression. AgNPs were synthesized and characterized using TEM, XRD and FTIR spectroscopy. A. baumannii (n = 200) were isolated and identified. Resistance pattern was determined and virulence genes (afa/draBC, cnf1, cnf2, csgA, cvaC, fimH, fyuA, ibeA, iutA, kpsMT II, PAI, papC, PapG II, III, sfa/focDE and traT) were screened using PCR. Biofilm formation was evaluated using Microtiter plate method. Then, the antimicrobial activity of AgNPs was evaluated by the well-diffusion method, growth kinetics and MIC determination. Inhibition of biofilm formation and the ability to disperse biofilms in exposure to AgNPs were evaluated. The effect of AgNPs on the expression of virulence and biofilm-related genes (bap, OmpA, abaI, csuA/B, A1S_2091, A1S_1510, A1S_0690, A1S_0114) were estimated using QRT-PCR. In vitro infection model for analyzing the antibacterial activity of AgNPs was done using a co-culture infection model of A. baumannii with human fibroblast skin cell line HFF-1 or Vero cell lines. A. baumannii had high level of resistance to antibiotics. Most of the isolates harbored the fimH, afa/draBC, cnf1, csgA and cnf2, and the majority of A. baumannii produced strong biofilms. AgNPs inhibited the growth of A. baumannii efficiently with MIC ranging from 4 to 25 µg/ml. A. baumannii showed a reduced growth rate in the presence of AgNPs. The inhibitory activity and the anti-biofilm activity of AgNPs were more pronounced against the weak biofilm producers. Moreover, AgNPs decreased the expression of kpsMII , afa/draBC,bap, OmpA, and csuA/B genes. The in vitro infection model revealed a significant antibacterial activity of AgNPs against extracellular and intracellular A. baumannii. AgNPs highly interrupted bacterial multiplication and biofilm formation. AgNPs downregulated the transcription level of important virulence and biofilm-related genes. Our findings provide an additional step towards understanding the mechanisms by which sliver nanoparticles interfere with the microbial spread and persistence.
我们的目的是从伤口感染中分离鲍曼不动杆菌（A.baumannii），确定其耐药性和毒力谱，并评估银纳米粒子（AgNPs）对细菌生长、毒力和生物膜相关基因表达的影响。使用 TEM、XRD 和 FTIR 光谱法合成和表征了 AgNPs。从 200 株鲍曼不动杆菌中分离并鉴定。采用纸片扩散法、微量肉汤稀释法和 MIC 测定法评价 AgNPs 的抗菌活性。采用微量滴定板法评价生物膜形成情况。然后，采用平板打孔法、生长动力学和 MIC 测定法评估 AgNPs 的抑菌活性。评价 AgNPs 对生物膜形成的抑制作用和暴露于 AgNPs 时分散生物膜的能力。采用 QRT-PCR 法评估 AgNPs 对毒力和生物膜相关基因（bap、OmpA、abaI、csuA/B、A1S_2091、A1S_1510、A1S_0690、A1S_0114）表达的影响。采用共培养感染模型，用人类成纤维细胞皮肤细胞系 HFF-1 或 Vero 细胞系与鲍曼不动杆菌进行体外感染模型，分析 AgNPs 的抗菌活性。鲍曼不动杆菌对抗生素有高水平的耐药性。大多数分离株携带 fimH、afa/draBC、cnf1、csgA 和 cnf2，大多数鲍曼不动杆菌产生强生物膜。AgNPs 对 A.baumannii 的 MIC 范围为 4 至 25μg/ml，对 A.baumannii 的生长有明显抑制作用。AgNPs 的抑菌活性和抗生物膜活性对弱生物膜生产者更为明显。此外，AgNPs 降低了 kpsMII、afa/draBC、bap、OmpA 和 csuA/B 基因的表达。体外感染模型显示 AgNPs 对细胞外和细胞内鲍曼不动杆菌具有显著的抗菌活性。AgNPs 高度干扰细菌的增殖和生物膜形成。AgNPs 下调了重要毒力和生物膜相关基因的转录水平。我们的研究结果为进一步了解银纳米粒子干扰微生物传播和持久性的机制提供了依据。
