Antagonistic relationships among Acinetobacter isolates

由鲍曼不动杆菌等革兰氏阴性病原体引起的医院感染已成为一种 在治疗免疫功能受损的个人和创伤患者方面面临的主要挑战。这些 感染包括呼吸机相关性肺炎、导管相关的尿路感染和无法愈合。 伤口感染，最终可能导致败血症。值得关注的是，生活的频率越来越高- 耐药鲍曼氏杆菌引起的威胁感染，加强了对新疗法的需求 接近了。最近的研究表明，鲍曼不动杆菌在临床环境中有丰富的分类群，而且 微生物多样性的减少导致了抗菌素耐药性的增加。然而，人们对此知之甚少。 从这些环境中分离的不动杆菌之间的生物和物理相互作用。 从该大学患者直接获得的越来越多的不动杆菌分离株的特征 密歇根医院系统在5年的时间里发现了鲍曼不动杆菌的“捕食者”菌株 抑制敏感(“猎物”)不动杆菌菌株的生长。这种表型表现为一个区域 清除集中接种的捕食者产生的软琼脂中的敏感细菌 菌株。含有一种新的多肽毒素的粗提物，属于核糖体合成和 翻译后修饰多肽(RIPP)可以从捕食者身上分离出来，然后添加到猎物中 导致细胞接触非接触生长抑制的菌株。我们的初步数据表明， 存在预测为合成、修饰和分泌该RIPP所需的基因，a 新型多肽毒素，是比较少见的。对我们收集的菌株进行筛选表明，大约3%的人携带 基因和表现出生长抑制表型。NCBI数据库中可用序列的分析 证实了这些基因的相对稀缺性。相比之下，包括多药在内的几种鲍曼不动杆菌菌株 耐药鲍曼不动杆菌分离株以及皮蒂不动杆菌对杀灭敏感。这个 本研究的主要目的是剖析不动杆菌分离株之间的这些拮抗作用。我们的目标是 目的：确定多肽毒素的性质及其分泌机制。此外，实验还包括 旨在揭示这种毒素是如何进入敏感菌株的，以及它通过什么机制抑制它们的生长。这些 研究将促进我们对毒素的作用的理解，并具有重要的翻译意义 精确药物治疗的潜力，因为使用毒素或其变体可能是一种有希望的手段 对抗多重耐药鲍曼不动杆菌引起的感染。

Nosocomial infections caused by gram-negative pathogens such as Acinetobacter baumannii have become a major challenge in the treatment of immunocompromised individuals and patients with traumatic injuries. These infections include ventilator-associated pneumonia, catheter-related urinary tract infections and non-healing wound infections that can ultimately lead to sepsis. Of significant concern is the increasing frequency of life- threatening infections caused by drug resistant A baumannii, reinforcing the need for new therapeutic approaches. Recent studies have shown that A. baumannii taxa are abundant in clinical environments and that decreases in microbial diversity contribute to increased antimicrobial resistance. However, little is known about the biological and physical interactions between Acinetobacter sp isolated from these environments. Characterization of a growing collection of Acinetobacter isolates obtained directly from patients at the University of Michigan Hospital System over a period of 5 years has identified “predator” strains of A. baumannii capable of inhibiting the growth of susceptible (“prey”) Acinetobacter strains. This phenotype is manifested as a zone of clearing of susceptible bacteria – embedded in soft agar - that emanates from centrally inoculated predator strains. Crude extracts containing a novel peptide toxin belonging to the family of ribosomally synthesized and posttranslationally modified peptides (RiPPs) can be isolated from the predator and subsequently added to prey strains resulting in cell contact-independent growth inhibition. Our preliminary data demonstrate that the presence of the genes predicted to be required for the synthesis, modification, and secretion of this RiPP, a novel peptide toxin, is relatively rare. Screening of our strain collection indicate that approximately 3 % carry the genes and display the growth inhibition phenotype. Analysis of available sequences in the NCBI database confirms the relatively scarceness of these genes. In contrast, several A. baumannii strains including multidrug resistant A. baumannii isolates as well as strains of the species Acinetobacter pittii are sensitive to killing. The primary objective of this study is to dissect these antagonistic interactions among Acinetobacter isolates. We aim to determine the nature of the peptide toxin and its mechanism of secretion. In addition, experiments are designed to reveal how the toxin enters susceptible strains and by what mechanism it inhibits their growth. These studies will advance our understanding of the role of the toxin and have significant translational implications with potential for precision drug therapy as the use of the toxin or variants thereof may represent a promising means of combating infections caused by multi-drug resistant A. baumannii.