Centre of Laboratory Medicine, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, Zhejiang, China.
Department of Clinical Laboratory, Feicheng Hospital of Traditional Chinese Medicine, Feicheng, Shandong, China.
mSystems. 2024 Oct 22;9(10):e0072224. doi: 10.1128/msystems.00722-24. Epub 2024 Sep 17.
carbapenemase (KPC) variants can contribute to resistance to ceftazidime-avibactam (CZA) in (KP). However, two-copy KPC variant-mediated resistance to CZA has rarely been reported to date. Here, we aimed to clarify the evolutionary trajectory of CZA resistance driven by mutations in double-copy to carried by the tandem core structure (IS-IS-IS) during treatment of ST11 carbapenem-resistant (CRKP). The CZA-resistant KP strain carried double-copy , a variant with alanine-threonine and aspartate-tyrosine substitutions at Ambler amino acid positions 172 (A172T) and 179 (D179Y) of . Clone experiments confirmed that, compared with that of the wild-type clone strain, the minimum inhibitory concentration of CZA increased 16-fold in the -mutant strain. Furthermore, protein structure analysis revealed the A172T and D179Y mutations of can have a direct effect on the binding affinity of CAZ and AVI for KPC. Sequence comparison revealed that was mutated in a double-copy format upon CZA exposure, which was carried by the IS-mediated tandem core structure IS-IS. This tandem core structure apparently evolves during infection, although not by self-transferring, and multiple IS-IS copy numbers could mediate transferable CZA resistance upon mobilization. In addition, compared with the wild-type gene, the gene had no fitness cost. In summary, our study highlighted the emergence of CZA-resistant variants in the ST11 clone and the presence of a double-copy in the IncFII-type plasmid, which is carried by a tandem core structure (ISIS-IS-IS).
To date, ceftazidime-avibactam (CZA) resistance caused by double-copy carbapenemase (KPC) variants has not been elucidated. The multicopy forms of carbapenem resistance genes carried by the same plasmid are relatively rare in most carbapenem-resistant . In this study, we elucidate the evolutionary trajectory of CZA resistance in ST11 carbapenem-resistant harboring a double-copy blaKPC and provide new insights into the mechanisms of acquired resistance to CZA.
碳青霉烯酶 (KPC) 变体可导致对头孢他啶-阿维巴坦 (CZA) 的耐药性在 (KP) 中。然而，迄今为止，很少有报道称两拷贝 KPC 变体介导对 CZA 的耐药性。在这里，我们旨在阐明由串联核心结构 (IS-IS-IS) 携带的双重拷贝 中的突变驱动的 CZA 耐药性的进化轨迹在治疗 ST11 碳青霉烯类耐药 （CRKP）期间。CZA 耐药的 KP 菌株携带双重拷贝 ，该变体在 中的天冬氨酸-苏氨酸和天冬氨酸-酪氨酸取代了安布勒氨基酸位置 172（A172T）和 179（D179Y）。克隆实验证实，与野生型 克隆株相比，CZA 突变株的最小抑菌浓度增加了 16 倍。此外，蛋白质结构分析表明， 中的 A172T 和 D179Y 突变可直接影响 CAZ 和 AVI 与 KPC 的结合亲和力。序列比较表明，CZA 暴露后， 以双重拷贝的形式发生突变，由 IS 介导的串联核心结构 IS-IS 携带。尽管不是通过自我转移，但这种串联核心结构显然在感染过程中进化，并且多个 IS-IS 拷贝数可以在动员时介导可转移的 CZA 耐药性。此外，与野生型 基因相比， 基因没有适应性成本。总之，我们的研究强调了 ST11 克隆中 CZA 耐药变体的出现，以及 IncFII 型质粒中存在的双重拷贝 ，该质粒由串联核心结构（ISIS-IS-IS）携带。
迄今为止，尚未阐明由双重拷贝碳青霉烯酶 (KPC) 变体引起的头孢他啶-阿维巴坦 (CZA) 耐药性。大多数碳青霉烯类耐药 中，同一质粒携带的碳青霉烯类耐药基因的多拷贝形式相对较少。在这项研究中，我们阐明了携带双重拷贝 blaKPC 的 ST11 碳青霉烯类耐药 中 CZA 耐药性的进化轨迹，并为获得性对 CZA 的耐药机制提供了新的见解。
