Jacobs Anna C, Sayood Khalid, Olmsted Stephen B, Blanchard Catlyn E, Hinrichs Steven, Russell David, Dunman Paul M
Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA.
FEMS Immunol Med Microbiol. 2012 Apr;64(3):403-12. doi: 10.1111/j.1574-695X.2011.00926.x. Epub 2012 Jan 23.
Acinetobacter baumannii has emerged as a bacterial pathogen of considerable healthcare concern. Yet, little is known about the organism's basic biological processes and the regulatory networks that modulate expression of its virulence factors and antibiotic resistance. Using Affymetrix GeneChips , we comprehensively defined and compared the transcriptomes of two A. baumannii strains, ATCC 17978 and 98-37-09, during exponential and stationary phase growth in Luria-Bertani (LB) medium. Results revealed that in addition to expected growth phase-associated metabolic changes, several putative virulence factors were dramatically regulated in a growth phase-dependent manner. Because a common feature between the two most severe types of A. baumannii infection, pneumonia and septicemia, includes the organism's dissemination to visceral organs via the circulatory system, microarray studies were expanded to define the expression properties of A. baumannii during growth in human serum. Growth in serum significantly upregulated iron acquisition systems, genes associated with epithelial cell adherence and DNA uptake, as well as numerous putative drug efflux pumps. Antibiotic susceptibility testing verified that the organism exhibits increased antibiotic tolerance when cultured in human serum, as compared to LB medium. Collectively, these studies provide researchers with a comprehensive database of A. baumannii's expression properties in LB medium and serum and identify biological processes that may contribute to the organism's virulence and antibiotic resistance.
鲍曼不动杆菌已成为一种引起医疗保健领域广泛关注的细菌病原体。然而，对于该生物体的基本生物学过程以及调节其毒力因子表达和抗生素耐药性的调控网络，我们却知之甚少。我们使用Affymetrix基因芯片，全面定义并比较了鲍曼不动杆菌ATCC 17978和98 - 37 - 09这两个菌株在Luria - Bertani（LB）培养基中指数生长期和稳定期的转录组。结果显示，除了预期的与生长阶段相关的代谢变化外，几种假定的毒力因子也以生长阶段依赖的方式受到显著调控。由于鲍曼不动杆菌最严重的两种感染类型，即肺炎和败血症，其一个共同特征是该生物体通过循环系统传播至内脏器官，因此我们扩展了微阵列研究，以确定鲍曼不动杆菌在人血清中生长时的表达特性。在血清中生长显著上调了铁获取系统、与上皮细胞黏附和DNA摄取相关的基因，以及众多假定的药物外排泵。抗生素敏感性测试证实，与在LB培养基中培养相比，该生物体在人血清中培养时表现出更高的抗生素耐受性。总的来说，这些研究为研究人员提供了一个关于鲍曼不动杆菌在LB培养基和血清中表达特性的综合数据库，并确定了可能有助于该生物体毒力和抗生素耐药性的生物学过程。
