Emergence of high-level colistin resistance mediated by multiple determinants, including mcr-1.1, mcr-8.2 and crrB mutations, combined with tigecycline resistance in an ST656 Klebsiella pneumoniae.
Emergence of high-level colistin resistance mediated by multiple determinants, including mcr-1.1, mcr-8.2 and crrB mutations, combined with tigecycline resistance in an ST656 Klebsiella pneumoniae.
复制标题
DOI：
10.3389/fcimb.2023.1122532
复制
发表时间：
2023
影响因子：
5.7
通讯作者：
中科院分区：
文献类型：
--
作者：
粘菌素和替加环素通常被认为是治疗多药耐药肺炎克雷伯菌感染的最后手段。粘菌素和替加环素耐药性的出现对全球卫生保健提出了挑战，并且由于治疗选择有限，与高死亡率相关。在这里，我们报告了ST656广泛耐药肺炎克雷伯菌菌株KP15-652，该菌株从中国患者的尿液中分离出来。药敏试验结果显示对替加环素、阿米卡星、左氧氟沙星、环丙沙星耐药，粘菌素高水平耐药（> ~ 2048 mg/L）。全基因组测序结果显示，该菌株含有1条染色体和7个质粒，其中4个质粒携带多个获得性耐药基因。转化/偶联试验和质粒固化试验证实，mcr-1.1、mcr-8.2和crrB突变是高水平粘菌素耐药的原因，而一系列外排泵基因，如tmexCD1-toprJ1、tet(a)和tet(M)，有助于替加环素耐药。mcr-1.1和tet(M)位于具有偶联传递电位的IncX1质粒上。mcr-8.2和tet(A)位于多复制子IncR/IncN质粒上，但不能通过偶联转移。此外，另一种可结合和融合质粒携带tmexCD1-toprJ1基因簇，这可能是由于is26介导的基于8-bp靶位复制的复制转位而产生的。重要的是，在该融合质粒上检测到一个复杂的携带多种抗性基因的1类整合子。综上所述，高水平的粘菌素耐药可能是由于染色体和携带mcr的质粒上多种因素的累积作用，并结合包括替加环素在内的许多其他耐药所致。应进行有效监测以防止进一步传播。
Colistin and tigecycline are usually regarded as the last resort for multidrug-resistant Klebsiella pneumoniae infection treatment. Emergence of colistin and tigecycline resistance poses a global healthcare challenge and is associated with high mortality due to limited therapeutic options. Here, we report the ST656 extensively drug-resistant K. pneumoniae strain KP15-652, which was isolated from a patient’s urine in China. Antimicrobial susceptibility testing showed it to be resistant to tigecycline, amikacin, levofloxacin, ciprofloxacin, and high-level colistin resistance (> 2048 mg/L). Whole-genome sequencing revealed that it harbors one chromosome and seven plasmids, including four plasmids carrying multiple acquired resistance genes. Transformation/conjugation tests and plasmid curing assays confirmed that mcr-1.1, mcr-8.2 and crrB mutations are responsible for the high-level colistin resistance and that a series of efflux pump genes, such as tmexCD1-toprJ1, tet(A) and tet(M), contribute to tigecycline resistance. mcr-1.1 and tet(M) are located on an IncX1 plasmid, which has conjugation transfer potential. mcr-8.2 and tet(A) are located on a multireplicon IncR/IncN plasmid but unable to be transferred via conjugation. Moreover, another conjugable and fusion plasmid carries the tmexCD1-toprJ1 gene cluster, which may have arisen due to IS26-mediated replicative transposition based on 8-bp target-site duplications. Importantly, a complex class 1 integron carrying various resistance genes was detected on this fusion plasmid. In conclusion, it is possible that the high-level of colistin resistance is caused by the accumulated effect of several factors on the chromosome and mcr-carrying plasmids, combined with many other resistances, including tigecycline. Effective surveillance should be performed to prevent further dissemination.