Yang Weiwei, Xu Heping, Zhao Yuanxun, Chen Wannan, Ma Xiaobo, Hu Fupin
Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China; Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China.
Department of Laboratory Medicine, Xiamen Key Laboratory of Genetic Testing, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, China; Department of Medical Microbiology, Fujian Key Laboratory of Tumor Microbiology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian, China.
Int J Antimicrob Agents. 2025 Jan;65(1):107388. doi: 10.1016/j.ijantimicag.2024.107388. Epub 2024 Nov 17.
In this study, we discovered bla in ceftazidime-avibactam resistant clinical isolates of K. pneumoniae from a patient with multiple comorbidities and investigated the resistance & transfer mechanism of bla.
K. pneumoniae strains carrying bla and bla were isolated from the patient. Antimicrobial susceptibility tests and whole genome sequencing were performed to investigate the phenotype & genotype of strains. Conjugation assays, cloning experiment, kinetic parameters measuring, outer membrane protein SDS-PAGE and qRT-PCR were performed to explore the spread and antimicrobial resistance mechanisms.
KPC-90 isolates had an insertion of two amino acids (Thr180_Ser181 ins Tyr Thr) compared to the wildtype KPC-2. Antimicrobial susceptibility testing of isolates with KPC-90 vs. KPC-2 showed ceftazidime-avibactam MICs of >128 vs. 1-2 mg/L, meropenem-vaborbactam MICs of 4 vs. 1 mg/L, meropenem MICs of 4-8 vs. >128 mg/L and imipenem MICs of 0.5-1 vs. 64 mg/L. Analysis of kinetic parameters of KPC-90 compared to KPC-2 showed decreased hydrolysis of carbapenems and increased IC50 of avibactam. Genetic characterization of the plasmid revealed that IS26 could mediate the intramolecular inversion, translocation and truncation of the resistance determinant region.
We have described the case of a patient infected with bla-carrying K. pneumoniae strains and investigated the mechanism of resistance to carbapenems and ceftazidime-avibactam associated with bla and its variants. We have also focused on the functional diversity of IS26 in relation to antimicrobial resistance. In the future, it is crucial to pay more attention to the evolution and horizontal transmission of bla.
在本研究中，我们从一名患有多种合并症的患者的耐头孢他啶 - 阿维巴坦肺炎克雷伯菌临床分离株中发现了bla，并研究了bla的耐药性及转移机制。
从该患者中分离出携带bla和bla的肺炎克雷伯菌菌株。进行了抗菌药物敏感性试验和全基因组测序，以研究菌株的表型和基因型。进行了接合试验、克隆实验、动力学参数测量、外膜蛋白SDS - PAGE和qRT - PCR，以探索其传播和抗菌耐药机制。
与野生型KPC - 2相比，KPC - 90分离株插入了两个氨基酸（Thr180_Ser181插入Tyr Thr）。对携带KPC - 90与KPC - 2的分离株进行抗菌药物敏感性测试显示，头孢他啶 - 阿维巴坦的MIC分别为>128 vs. 1 - 2 mg/L，美罗培南 - 巴硼巴坦的MIC分别为4 vs. 1 mg/L，美罗培南的MIC分别为4 - 8 vs. >128 mg/L，亚胺培南的MIC分别为0.5 - 1 vs. 64 mg/L。与KPC - 2相比，KPC - 90的动力学参数分析显示碳青霉烯类水解减少，阿维巴坦的IC50增加。质粒的遗传特征表明，IS26可介导耐药决定区的分子内倒位、易位和截短。
我们描述了一例感染携带bla的肺炎克雷伯菌菌株的患者病例，并研究了与bla及其变体相关的对碳青霉烯类和头孢他啶 - 阿维巴坦的耐药机制。我们还关注了IS26在抗菌耐药性方面的功能多样性。未来，更加关注bla的进化和水平传播至关重要。
