National Institute for Infectious Diseases (INMI) L. Spallanzani, Rome, Italy.
San Filippo Neri Hospital, Rome, Italy.
Clin Microbiol Infect. 2021 Jul;27(7):1040.e1-1040.e6. doi: 10.1016/j.cmi.2021.03.001. Epub 2021 Mar 26.
To analyse the strains collected during a 1-year survey of ceftazidime-avibactam-resistant KPC-producing Klebsiella pneumoniae, in order to investigate the molecular mechanisms potentially responsible for their resistant phenotype.
Clinical KPC-producing K. pneumoniae isolates were collected from 31 patients in six different hospitals in Rome. For eight of the patients, an additional strain grown before the start of treatment was also available, bringing the total of isolates studied to 39. Antimicrobial susceptibility was determined by automated system, broth microdiluition and E-test as appropriate. In silico analysis of acquired resistance genes was achieved by whole-genome sequencing, while multilocus sequence typing and core genome multilocus sequence typing were employed for molecular typing. Mutations associated with ceftazidime-avibactam resistance were identified by Sanger sequencing of the bla gene. Possible mutations in OmpK35 and OmpK36 outer membrane proteins were also investigated.
Molecular analyses highlighted the circulation of the ST512, 101 and 307 high-risk clones; 26 of the 31 patients carried a mutated KPC variant, five had a wild-type KPC-3. Among the KPC variants detected, 11 were different mutations within the bla gene, four of which were novel mutational changes.
Different mutations including single amino-acid substitutions, insertions or deletions within the bla gene were found in 26/31 ceftazidime-avibactam-resistant KPC-producing K. pneumoniae strains belonging to high-risk clones circulating in Italy. Of note, in 14/31 cases the isolates displayed resistance to both ceftazidime-avibactam and carbapenems, raising concerns for the possible selection of a multidrug-resistant phenotype.
分析在一项为期 1 年的耐头孢他啶-阿维巴坦产 KPC 肺炎克雷伯菌的研究中收集的菌株，以研究可能导致其耐药表型的分子机制。
从罗马六家不同医院的 31 名患者中收集临床产 KPC 的肺炎克雷伯菌分离株。对于其中 8 名患者，在开始治疗前还获得了另一个菌株，使研究的分离株总数达到 39 个。根据自动系统、肉汤微量稀释和 E 试验适当确定抗菌药物敏感性。通过全基因组测序实现获得性耐药基因的计算机分析，而多位点序列分型和核心基因组多位点序列分型用于分子分型。通过 bla 基因的 Sanger 测序鉴定与头孢他啶-阿维巴坦耐药相关的突变。还研究了 OmpK35 和 OmpK36 外膜蛋白的可能突变。
分子分析突出了 ST512、101 和 307 高危克隆的循环；31 名患者中有 26 名携带突变型 KPC 变体，5 名携带野生型 KPC-3。在所检测的 KPC 变体中，11 个是 bla 基因内的不同突变，其中 4 个是新的突变变化。
在属于意大利流行的高危克隆的 26/31 株耐头孢他啶-阿维巴坦产 KPC 肺炎克雷伯菌中，bla 基因内发现了不同的突变，包括单个氨基酸取代、插入或缺失。值得注意的是，在 31 例中有 14 例分离株对头孢他啶-阿维巴坦和碳青霉烯类均耐药，这引起了对可能选择多药耐药表型的关注。
