Zhang Yawei, Liao Kang, Gao Hua, Wang Qi, Wang Xiaojuan, Li Henan, Wang Ruobing, Wang Hui
Department of Clinical Laboratory, Peking University People's HospitalBeijing, China.
Department of Clinical Laboratory, First Affiliated Hospital of Sun Yat-sen UniversityGuangzhou, China.
Front Cell Infect Microbiol. 2017 Jun 8;7:242. doi: 10.3389/fcimb.2017.00242. eCollection 2017.
Although coexistence of and in has been reported, little is known about the fitness and virulence of such strains. Three carbapenem-resistant (GZ1, GZ2, and GZ3) successively isolated from one patient in 2015 were investigated for microbiological fitness and virulence. GZ1 and GZ2 were also resistant to colistin. To verify the association between plasmids and fitness, growth kinetics of the transconjugants were performed. We also analyzed genomic sequences of GZ2 and GZ3 using PacBio sequencing. GZ1 and GZ2 (ST10) co-harbored and , while GZ3 (ST4981) carried only . GZ3 demonstrated significantly more rapid growth ( < 0.001) and overgrew GZ2 with a competitive index of 1.0157 (4 h) and 2.5207 (24 h). Increased resistance to serum killing and mice mortality was also identified in GZ3. While GZ2 had four plasmids (IncI2, IncX3, IncHI2, IncFII), GZ3 possessed one plasmid (IncFII). The genetic contexts of in GZ2 and GZ3 were identical but inserted into different backbones, IncX3 (102,512 bp) and IncFII (91,451 bp), respectively. The growth was not statistically different between the transconjugants with or plasmid and recipient ( = 0.6238). Whole genome sequence analysis revealed that 28 virulence genes were specific to GZ3, potentially contributing to increased virulence of GZ3. Decreased fitness and virulence in a and co-harboring ST10 was found alongside a ST4981 strain with only . Acquisition of or plasmid did not lead to considerable fitness costs, indicating the potential for dissemination of and in .
尽管已有报道在肺炎克雷伯菌中同时存在 blaKPC 和 blaNDM，但对此类菌株的适应性和毒力了解甚少。对 2015 年从一名患者身上先后分离出的三株耐碳青霉烯类肺炎克雷伯菌（GZ1、GZ2 和 GZ3）进行了微生物适应性和毒力研究。GZ1 和 GZ2 还对黏菌素耐药。为验证质粒与适应性之间的关联，对转接合子的生长动力学进行了研究。我们还使用 PacBio 测序分析了 GZ2 和 GZ3 的基因组序列。GZ1 和 GZ2（ST10）共同携带 blaKPC 和 blaNDM，而 GZ3（ST4981）仅携带 blaNDM。GZ3 显示出明显更快的生长速度（P < 0.001），并以 1.0157（4 小时）和 2.5207（24 小时）的竞争指数超过 GZ2。GZ3 对血清杀伤的抵抗力增加以及小鼠死亡率也有所升高。虽然 GZ2 有四个质粒（IncI2、IncX3、IncHI2、IncFII），但 GZ3 拥有一个质粒（IncFII）。GZ2 和 GZ3 中 blaNDM 的遗传背景相同，但分别插入到不同的主干 IncX3（102,512 bp）和 IncFII（91,451 bp）中。携带 blaKPC 或 blaNDM 质粒的转接合子与受体之间的生长在统计学上没有差异（P = 0.6238）。全基因组序列分析表明，28 个毒力基因是 GZ3 特有的，可能导致 GZ3 的毒力增加。在一株同时携带 blaKPC 和 blaNDM 的 ST10 肺炎克雷伯菌中发现其适应性和毒力降低，而与之相比，一株仅携带 blaNDM 的 ST4981 菌株则相反。获得 blaKPC 或 blaNDM 质粒并未导致明显的适应性代价，这表明 blaKPC 和 blaNDM 在肺炎克雷伯菌中有传播的潜力。
