Huang Xiangning, Shen Siquan, Chang Fan, Liu Xin, Yue Jinxi, Xie Ning, Yin Lin, Hu Fupin, Xiao Daiwen
Department of Laboratory Medicine and Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China.
Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China.
Microbiol Spectr. 2023 Sep 29;11(5):e0072523. doi: 10.1128/spectrum.00725-23.
The emergence of various new carbapenemase (KPC) variants leading to ceftazidime-avibactam treatment failure is a new challenge in current clinical anti-infection treatment. Here, we report a ceftazidime-avibactam-resistant 1072-2 clinical strain carrying a novel KPC variant, KPC-134, which differs from KPC-2 by both single mutation (D178A) and 8-amino acid insertions (asp-asp-asn-arg-ala-pro-asn-lys). The results of antimicrobial susceptibility testing showed that the isolate was resistant to meropenem (MIC = 4 mg/L), ceftazidime (MIC ≥ 32 mg/L), cefepime (MIC ≥128 mg/L), aztreonam (MIC ≥128 mg/L), and ceftazidime-avibactam (MIC ≥128 mg/L) but sensitive to imipenem (MIC = 0.5 mg/L), imepenem-relebactam (MIC = 0.5 mg/L), meropenem-vaborbactam (MIC = 2 mg/L), and aztreonam-avibactam (MIC = 4 mg/L). The plasmid containing was isolated from , and the gene was cloned into plasmid pHSG398 and transformed into an DH5α to observe changes in antimicrobial resistance. The results indicated that the transformant was positive for and increased MICs of ceftazidime-avibactam, ceftazidime, cefepime, and aztreonam by 512-fold, 256-fold, 16-fold, and 4-fold, respectively, compared with the recipient. The results of third-generation sequencing showed that the gene was carried by a 133,789 bp IncFII-IncR plasmid, and many common resistance genes (including , , , , and ) along with the IS, , , IS-like, and Tn elements were identified. IMPORTANCE The emergence of various new KPC variants leading to ceftazidime-avibactam treatment failure is a new challenge for clinical anti-infection treatment. Here, we describe the characterization of a ceftazidime-avibactam-resistant blaKPC-134-positive clinical strain for the first time. bearing with KPC variant often mislead clinical anti-infection treatment because of their unique antimicrobial susceptibility profile and the tendency of conventional carbapenemase assays to give false negative results. Therefore, timely identification of KPC variants and effective anti-infective therapy are key to saving infected patients.
各种新型碳青霉烯酶（KPC）变体的出现导致头孢他啶-阿维巴坦治疗失败，这是当前临床抗感染治疗中的一项新挑战。在此，我们报告一株对头孢他啶-阿维巴坦耐药的1072-2临床菌株，其携带一种新型KPC变体KPC-134，该变体与KPC-2的区别在于一个单突变（D178A）和8个氨基酸的插入（asp-asp-asn-arg-ala-pro-asn-lys）。抗菌药敏试验结果显示，该分离株对美罗培南（MIC = 4 mg/L）、头孢他啶（MIC≥32 mg/L）、头孢吡肟（MIC≥128 mg/L）、氨曲南（MIC≥128 mg/L）和头孢他啶-阿维巴坦（MIC≥128 mg/L）耐药，但对亚胺培南（MIC = 0.5 mg/L）、亚胺培南-瑞来巴坦（MIC = 0.5 mg/L）、美罗培南-法硼巴坦（MIC = 2 mg/L）和氨曲南-阿维巴坦（MIC = 4 mg/L）敏感。从该菌株中分离出携带blaKPC-134的质粒，并将blaKPC-134基因克隆到质粒pHSG398中，然后转化到大肠杆菌DH5α中，以观察抗菌耐药性的变化。结果表明，与受体菌相比，转化子blaKPC-134呈阳性，头孢他啶-阿维巴坦、头孢他啶、头孢吡肟和氨曲南的MIC分别增加了512倍、256倍、16倍和4倍。三代测序结果显示，blaKPC-134基因由一个133,789 bp的IncFII-IncR质粒携带，并鉴定出许多常见耐药基因（包括blaTEM、blaSHV、blaCTX-M、blaOXA-48和blaNDM）以及IS、ISEcp1、ISEcp2、IS-like和Tn元件。重要性各种新型KPC变体的出现导致头孢他啶-阿维巴坦治疗失败，这是临床抗感染治疗面临的新挑战。在此，我们首次描述了一株对头孢他啶-阿维巴坦耐药的blaKPC-134阳性临床菌株的特征。携带KPC变体的菌株因其独特的抗菌药敏谱以及传统碳青霉烯酶检测易出现假阴性结果的倾向，常常会误导临床抗感染治疗。因此，及时鉴定KPC变体并进行有效的抗感染治疗是挽救感染患者的关键。
