State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China.
Department of Microbiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
Microbiol Spectr. 2022 Jun 29;10(3):e0268821. doi: 10.1128/spectrum.02688-21. Epub 2022 May 17.
The convergence of hypervirulence to carbapenem-resistant K. pneumoniae (CRKP) in a highly transmissible ST11 clone poses a great challenge to public health and anti-infection therapy. Recently, we revealed that an expanding repertoire of diversified KPC-2-producing plasmids occurs in these high-risk clones. Here, we report a clinical case infected with a rare isolate of ST437 CRKP, K186, which exhibited KPC-2 production. Apart from its 5,322,657-bp long chromosome, whole-genome sequencing of strain K186 elucidated three distinct resistance plasmids (designated pK186_1, pK186_2, and pK186_KPC, respectively). Unlike the prevalently larger form of KPC-2-producing plasmids (120 to ~170 kb) earlier we observed, pK186_KPC is an IncN-type, small plasmid of 26,012bp in length. Combined with the colinear alignment of plasmid genome, the analyses of insertion sequences further suggested that this carbapenem-resistant pK186_KPC might arise from the cointegration of its ancestral IncN and IncFII plasmids, exclusively relying on IS-based transposition events. Taken together, the result represents an unusual example of -bearing small plasmids, and highlights an ongoing arsenal of diversified carriers benefiting the transferability of KPC-2 carbapenem resistance. A rare ST437 isolate termed K186 was clinically determined which was unlike ST11, the dominant sequence type of CRKP. Whole-genome sequencing enabled us to discover three distinct resistance plasmids, namely, pK186_1, pK186_2, and pK186_KPC. Among them, pK186_KPC appears as a unique plasmid ~26 kb in size, much smaller than the prevalent forms (120 to ~170 kb). Intriguingly, genetic analysis suggests that it might originate from Proteus mirabilis. This result constitutes an additional example of differentiated plasmid vehicles dedicated to the emergence and dissemination of KPC-2 carbapenem resistance.
一种高传播性 ST11 克隆的超毒力碳青霉烯类耐药肺炎克雷伯菌 (CRKP)，对公共卫生和抗感染治疗构成了巨大挑战。最近，我们发现这些高危克隆中存在不断扩大的多样化 KPC-2 产生质粒库。在此，我们报告了一例感染罕见 ST437 CRKP 分离株 K186 的临床病例，该分离株表现出 KPC-2 的产生。除了其 5322657bp 长的染色体外，对 K186 菌株的全基因组测序揭示了三个不同的耐药质粒（分别命名为 pK186_1、pK186_2 和 pK186_KPC）。与我们之前观察到的流行的更大形式的 KPC-2 产生质粒 (120 到 ~170kb)不同，pK186_KPC 是一种 IncN 型小质粒，长度为 26012bp。结合质粒基因组的共线性比对和插入序列分析，进一步表明这种碳青霉烯类耐药的 pK186_KPC 可能是其祖先 IncN 和 IncFII 质粒的共同整合，仅依赖于基于 IS 的转位事件。总之，该结果代表了一种携带小质粒的罕见例子，并强调了多样化载体的不断发展，有利于 KPC-2 碳青霉烯类耐药性的转移。临床确定了一种罕见的 ST437 分离株，称为 K186，它与 CRKP 的主要序列类型 ST11 不同。全基因组测序使我们能够发现三种不同的耐药质粒，即 pK186_1、pK186_2 和 pK186_KPC。其中，pK186_KPC 是一种独特的大小约 26kb 的质粒，远小于流行形式 (120 到 ~170kb)。有趣的是，遗传分析表明它可能起源于奇异变形杆菌。这一结果构成了另一个分化质粒载体专门用于 KPC-2 碳青霉烯类耐药性的出现和传播的例子。
