Repizo Guillermo D, Gagné Stéphanie, Foucault-Grunenwald Marie-Laure, Borges Vitor, Charpentier Xavier, Limansky Adriana S, Gomes João Paulo, Viale Alejandro M, Salcedo Suzana P
Bases Moléculaires et Structurales des Systèmes Infectieux, CNRS UMR 5086, Université Lyon 1, Institut de Biologie et Chimie des Protéines, Lyon, France.
Unité de Microbiologie, Adaptation et Pathogénie, CNRS UMR 5240, Université Lyon 1, Villeurbanne, France.
PLoS One. 2015 Sep 24;10(9):e0138265. doi: 10.1371/journal.pone.0138265. eCollection 2015.
Gram-negative bacteria, such as Acinetobacter baumannii, are an increasing burden in hospitals worldwide with an alarming spread of multi-drug resistant (MDR) strains. Herein, we compared a type strain (ATCC17978), a non-clinical isolate (DSM30011) and MDR strains of A. baumannii implicated in hospital outbreaks (Ab242, Ab244 and Ab825), revealing distinct patterns of type VI secretion system (T6SS) functionality. The T6SS genomic locus is present and was actively transcribed in all of the above strains. However, only the A. baumannii DSM30011 strain was capable of killing Escherichia coli in a T6SS-dependent manner, unlike the clinical isolates, which failed to display an active T6SS in vitro. In addition, DSM30011 was able to outcompete ATCC17978 as well as Pseudomonas aeruginosa and Klebsiella pneumoniae, bacterial pathogens relevant in mixed nosocomial infections. Finally, we found that the T6SS of DSM30011 is required for host colonization of the model organism Galleria mellonella suggesting that this system could play an important role in A. baumannii virulence in a strain-specific manner.
革兰氏阴性菌，如鲍曼不动杆菌，在全球医院中造成的负担日益加重，多重耐药（MDR）菌株的传播令人担忧。在此，我们比较了一株模式菌株（ATCC17978）、一株非临床分离株（DSM30011）以及与医院暴发相关的鲍曼不动杆菌多重耐药菌株（Ab242、Ab244和Ab825），揭示了VI型分泌系统（T6SS）功能的不同模式。T6SS基因组位点在上述所有菌株中均存在且处于活跃转录状态。然而，与临床分离株不同，只有鲍曼不动杆菌DSM30011菌株能够以T6SS依赖的方式杀死大肠杆菌，临床分离株在体外未能显示出活跃的T6SS。此外，DSM30011能够胜过ATCC17978以及铜绿假单胞菌和肺炎克雷伯菌，这两种细菌是混合医院感染中的相关病原菌。最后，我们发现DSM30011的T6SS是模式生物大蜡螟宿主定殖所必需的，这表明该系统可能以菌株特异性方式在鲍曼不动杆菌的毒力中发挥重要作用。
