López María, Mayer Celia, Fernández-García Laura, Blasco Lucía, Muras Andrea, Ruiz Federico Martín, Bou German, Otero Ana, Tomás María
Department of Microbiology, Complejo Hospitalario Universitario A Coruña (CHUAC)-INIBIC, A Coruña, Spain.
Spanish Network for Research in Infectious Diseases (REIPI), Virgen Macarena, Seville, Spain.
PLoS One. 2017 Mar 22;12(3):e0174454. doi: 10.1371/journal.pone.0174454. eCollection 2017.
Acinetobacter baumannii is an important pathogen that causes nosocomial infections generally associated with high mortality and morbidity in Intensive Care Units (ICUs). Currently, little is known about the Quorum Sensing (QS)/Quorum Quenching (QQ) systems of this pathogen. We analyzed these mechanisms in seven clinical isolates of A. baumannii. Microarray analysis of one of these clinical isolates, Ab1 (A. baumannii ST-2_clon_2010), previously cultured in the presence of 3-oxo-C12-HSL (a QS signalling molecule) revealed a putative QQ enzyme (α/ß hydrolase gene, AidA). This QQ enzyme was present in all non-motile clinical isolates (67% of which were isolated from the respiratory tract) cultured in nutrient depleted LB medium. Interestingly, this gene was not located in the genome of the only motile clinical strain growing in this medium (A. baumannii strain Ab421_GEIH-2010 [Ab7], isolated from a blood sample). The AidA protein expressed in E. coli showed QQ activity. Finally, we observed downregulation of the AidA protein (QQ system attenuation) in the presence of H2O2 (ROS stress). In conclusion, most of the A. baumannii clinical strains were not surface motile (84%) and were of respiratory origin (67%). Only the pilT gene was involved in surface motility and related to the QS system. Finally, a new QQ enzyme (α/ß hydrolase gene, AidA protein) was detected in these strains.
鲍曼不动杆菌是一种重要的病原体，可引起医院感染，通常与重症监护病房（ICU）的高死亡率和高发病率相关。目前，对于这种病原体的群体感应（QS）/群体猝灭（QQ）系统知之甚少。我们分析了7株鲍曼不动杆菌临床分离株中的这些机制。对其中一株临床分离株Ab1（鲍曼不动杆菌ST-2_clon_2010）进行微阵列分析，该菌株先前在3-氧代-C12-HSL（一种QS信号分子）存在的情况下培养，结果显示出一种假定的QQ酶（α/β水解酶基因，AidA）。这种QQ酶存在于所有在营养耗尽的LB培养基中培养的非运动性临床分离株中（其中67%分离自呼吸道）。有趣的是，该基因并不存在于在这种培养基中生长的唯一运动性临床菌株（从血液样本中分离出的鲍曼不动杆菌菌株Ab421_GEIH-2010 [Ab7]）的基因组中。在大肠杆菌中表达的AidA蛋白表现出QQ活性。最后，我们观察到在过氧化氢（ROS应激）存在的情况下，AidA蛋白下调（QQ系统减弱）。总之，大多数鲍曼不动杆菌临床菌株不具有表面运动性（84%），且来源于呼吸道（67%）。只有pilT基因参与表面运动性并与QS系统相关。最后，在这些菌株中检测到一种新的QQ酶（α/β水解酶基因，AidA蛋白）。
