Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy.
Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy.
mSphere. 2024 Sep 25;9(9):e0042324. doi: 10.1128/msphere.00423-24. Epub 2024 Aug 22.
Carbapenemase-producing represents a major public health issue globally. Isolates with resistance to the newest drugs, like ceftazidime/avibactam (CZA), are increasingly reported. In this study, we analyzed the evolution of KPC-3-producing sequence type (ST) 512 . strains isolated at three different times (hospitalization days 45, 56, and 78) from the same patient, two of which were observed in a pericholecystic liver abscess. The three isolates (295Kp, 304Kp, and hmv-318Kp) from the same patient were subjected to antimicrobial susceptibility testing, whole-genome sequencing, sedimentation assay, biofilm measurement, serum resistance assay, macrophage phagocytosis, and adhesion assays. KPC-producing isolate hmv-318Kp exhibited carbapenem susceptibility, hypermucoviscous (hmv) colony phenotype and CZA resistance. Virulence markers of hypervirulent were absent. Two non-synonymous mutations were identified in the hmv-318Kp genome comparing with isogenic strains: a single-nucleotide polymorphism (SNP) occurred in the pKpQIL plasmid, changing in the gene variant, conferring CZA resistance; and a second SNP occurred in the gene of the capsular biosynthesis cluster, encoding a tyrosine kinase, resulting in the F557S Wzc protein mutation. The strain exhibiting an hmv phenotype (hmv-Kp) phenotype has been previously associated with amino acid substitutions occurring in the Wzc tyrosin kinase protein. We observed evolution of the ST512 strain to CZA resistance and acquisition of hypermucoviscosity. The pathogenetic role of the detected Wzc substitution is not fully elucidated, but other Wzc mutations were previously reported in hmv . Wzc mutants may be more frequent than expected and an underreported cause of hypermucoviscosity in clinical isolates.
Here we describe the evolution of KPC-3-producing ST512 isolated at three different times from the same patient of which the last one, from a biliary abscess, showed CZA resistance by KPC-31 production and manifested hmv colony phenotype. Hypervirulent (hv-Kp) isolates are increasingly reported worldwide. Their hypervirulent traits are associated with the presence of rmpA/A2 genes and an hmv. In this study, we identified an hmv-Kp that lacked the rmpA-D cluster but showed an amino acid substitution in the Wzc tyrosin kinase protein, involved in the capsular biosynthesis. This hmv-Kp strain emerged and evolved resistance to ceftazidime/avibactam resistance in a liver abscess of a patient. Our findings suggest that wzc mutations may be underreported, making it challenging to distinguish hv-Kp from "classic" with an hmv phenotype.
产生碳青霉烯酶的代表了一个主要的全球公共卫生问题。对最新药物（如头孢他啶/阿维巴坦（CZA））具有耐药性的分离株的报道越来越多。在这项研究中，我们分析了在同一患者的三个不同时间（住院第 45、56 和 78 天）分离的产 KPC-3 型 512 序列型（ST） 菌株的演变。其中两个在胆囊周围肝脓肿中观察到。对来自同一患者的三个 分离株（295Kp、304Kp 和 hmv-318Kp）进行了药敏试验、全基因组测序、沉降试验、生物膜测量、血清抗性试验、巨噬细胞吞噬和粘附试验。产 KPC 的分离株 hmv-318Kp 表现出对碳青霉烯类药物的敏感性、高粘液（hmv）菌落表型和 CZA 耐药性。超毒力 的毒力标记物不存在。在与同源株相比，hmv-318Kp 基因组中发现了两个非同义突变：单核苷酸多态性（SNP）发生在 pKpQIL 质粒中，改变了 基因变异，导致 CZA 耐药；第二个 SNP 发生在荚膜生物合成簇的 基因中，编码酪氨酸激酶，导致 F557S Wzc 蛋白突变。表现出 hmv 表型（hmv-Kp）表型的 菌株以前与发生在 Wzc 酪氨酸激酶蛋白中的氨基酸取代有关。我们观察到 ST512 菌株对 CZA 耐药性的进化和获得高粘液性。检测到的 Wzc 取代的发病机制作用尚未完全阐明，但以前在 hmv 中报道过其他 Wzc 突变。Wzc 突变体可能比预期更频繁，并且是临床分离株中高粘液性的未被充分报道的原因。
在这里，我们描述了在同一患者的三个不同时间从同一患者中分离出的产 KPC-3 的 ST512 的演变，其中最后一个来自胆管脓肿，通过 KPC-31 的产生表现出 CZA 耐药性，并表现出 hmv 菌落表型。在全球范围内越来越多地报道了具有超毒力（hv-Kp）的 分离株。它们的超毒力特征与 rmpA/A2 基因和 hmv 的存在有关。在这项研究中，我们鉴定了一个缺乏 rmpA-D 簇但表现出参与荚膜生物合成的 Wzc 酪氨酸激酶蛋白中的氨基酸取代的 hmv-Kp。这种 hmv-Kp 菌株在一名肝脓肿患者中出现并对头孢他啶/阿维巴坦产生耐药性。我们的研究结果表明，wzc 突变可能被低估，使得难以将 hv-Kp 与具有 hmv 表型的“经典” 区分开来。
