Chen Jiawei, Zeng Yu, Zhang Rong, Cai Jiachang
Clinical Microbiology Laboratory, The Second Affiliated Hospital of Zhejiang University School of Medicine, Zhejiang University, Hangzhou, China.
Front Microbiol. 2021 Sep 16;12:702956. doi: 10.3389/fmicb.2021.702956. eCollection 2021.
Three carbapenem-resistant (CRKP; strains KP-426, KP-C76, and KP-CT77) were isolated from a patient with severe burns during the treatment of colistin and tigecycline. Single-nucleotide polymorphism typing showed that three ST11 CRKP were clonally related. Three isolates harbored the same set of antimicrobial resistance genes. , , , and genes were located on the same 128,928-bp IncFII/IncR plasmid. (A), , , and genes were located on a plasmid with an unknown Inc-type. , , and were chromosomal genes. An IS and an IS were found in the promoter region of the gene of two colistin-resistant CRKP, KP-C76, and KP-CT77, respectively. A novel amino acid substitution, G300E, was identified in the type 1 Tet(A) variant of KP-CT77 which exhibited high-level tigecycline resistance compared to strains KP-426 and KP-C76 (MIC of 32, 4, and 4mg/l, respectively). Conjugation and cloning experiments confirmed that the mutated Tet(A) resulted in a 4-fold increase in tigecycline minimal inhibitory concentration (MIC) of . Three CRKP belonged to the K64 serotype and possessed a similar IncHI1B/repB virulence plasmid carrying , , and . The survival rates of injected with KP-426, KP-C76, and KP-CT77 were 4.2, 20.8, and 8.3%, respectively. The emergence of colistin and tigecycline resistance in carbapenem-resistant hypervirulent posed a serious threat to clinical anti-infective therapy. The type 1 Tet(A) variant carrying G300E mutation, which conferred significantly elevated tigecycline MIC and was located on a conjugative plasmid, needs attention.
从一名严重烧伤患者在接受黏菌素和替加环素治疗期间分离出三株耐碳青霉烯类肺炎克雷伯菌（CRKP；菌株KP - 426、KP - C76和KP - CT77）。单核苷酸多态性分型显示这三株ST11 CRKP具有克隆相关性。三株分离株携带相同的一组抗菌耐药基因。blaNDM - 1、blaOXA - 48、blaTEM - 1和blaCTX - M - 15基因位于同一个128,928碱基对的IncFII/IncR质粒上。（A）blaIMP - 4、blaVIM - 2、blaSPM - 1和blaGIM - 1基因位于一个Inc类型未知的质粒上。blaKPC - 2、blaSHV - 18和blaAmpC是染色体基因。在两株耐黏菌素的CRKP（KP - C76和KP - CT77）的mgrB基因启动子区域分别发现了一个ISEcp1和一个ISEcp2。在KP - CT77的1型Tet(A)变体中鉴定出一个新的氨基酸取代G300E，与菌株KP - 426和KP - C76相比，该变体表现出高水平的替加环素耐药性（MIC分别为32、4和4mg/l）。接合和克隆实验证实，突变的Tet(A)导致替加环素对KP - CT77的最低抑菌浓度（MIC）增加了4倍。三株CRKP属于K64血清型，并且拥有一个携带rmpA、rmpA2和bcp的相似的IncHI1B/repB毒力质粒。用KP - 426、KP - C76和KP - CT77注射小鼠后的存活率分别为4.2%、20.8%和8.3%。耐碳青霉烯类高毒力肺炎克雷伯菌中黏菌素和替加环素耐药性的出现对临床抗感染治疗构成了严重威胁。携带G300E突变的1型Tet(A)变体，其替加环素MIC显著升高且位于接合性质粒上，需要引起关注。
