Characterization of OXA-1224, a novel OXA-213-like β-lactamase encoded by the chromosome of Acinetobacter pittii

IF 4.6 2区医学 Q1 INFECTIOUS DISEASES

International Journal of Antimicrobial Agents Pub Date : 2025-05-13 DOI:10.1016/j.ijantimicag.2025.107536

Zeshi Liu , Siquan Shen , Jing Lei , Shuai Zhao , Xue Zhang , Chengkang Tang , Shi Wu , Ke Lei , Jian Yin , Yanping Zhang , Yan Guo , Yan Geng , Fupin Hu

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Abstract

Objectives

This study investigates the transfer mechanism and functional properties of OXA-1224, the novel d-class β-lactase in the clinical isolate Acinetobacter pittii (A. pittii) PT-01.

Methods

Bacterial identification was performed using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and resistance genes were identified via polymerase chain reaction (PCR) and DNA sequencing. Antimicrobial susceptibility of A. pittii PT-01 and its recombinant transformants carrying bla_OXA-1224 was determined by broth microdilution method. Purified OXA-213 and OXA-1224 proteins were evaluated by the enzymatic reaction kinetics test.

Results

A. pittii PT-01 was susceptible to amikacin, tigecycline, polymyxin B, ceftazidime, cefepime, cefoperazone-sulbactam, and piperacillin-tazobactam, but resistant to imipenem and meropenem. The strain harboured bla_OXA-72 and a novel bla_OXA-213 variant: bla_OXA-1224. Recombinant strains expressing bla_OXA-1224 showed an 8-fold and 16-fold increase in minimum inhibitory concentrations (MICs) for imipenem and meropenem, respectively, compared to the control strain Acinetobacter baumannii (A. baumannii) ATCC 17978. Enzymatic assays indicated that OXA-1224 had a higher Km value for nitrocefin and stronger affinity for imipenem (Km = 496.7) and meropenem (Km = 126.1) compared to OXA-213. Catalytic efficiency for imipenem and meropenem was also increased with OXA-1224 compared to OXA-213. OXA-1224 has a higher affinity for imipenem (Km/Kcat = 3.362) and meropenem (Km/Kcat = 4.837) compared to OXA-213 (Km/Kcat = 2.469, Km /Kcat = 2.547, respectively). However, OXA-1224 showed minimal activity against the third-generation cephalosporin ceftazidime (Km > 1000).

Conclusions

The novel β-lactamase bla_OXA-1224 from a clinical A. pittii isolate confers resistance to carbapenems only in vitro, demonstrating increased MICs and greater catalytic efficiency for carbapenems compared to bla_OXA-213. However, its activity against cephalosporins remains limited.

查看原文本刊更多论文

pittii不动杆菌染色体编码的一种新型oxa -213样β-内酰胺酶OXA-1224的鉴定。

目的：研究新型d类β-乳糖酶OXA-1224在临床分离的pittii不动杆菌PT-01中的转移机制和功能特性。方法：采用MALDI-TOF质谱法进行细菌鉴定，采用PCR和DNA测序法鉴定耐药基因。采用微量肉汤稀释法测定皮氏弧菌PT-01及其携带blaOXA-1224的重组转化体的抗菌敏感性。通过酶促反应动力学试验对纯化的OXA-213和OXA-1224蛋白进行评价。结果：A. pittii PT-01对阿米卡星、替加环素、多粘菌素B、头孢他啶、头孢吡肟、头孢哌酮舒巴坦、哌拉西林他唑巴坦敏感，对亚胺培南、美罗培南耐药。该菌株含有blaOXA-72和一种新的blaOXA-213变体：blaOXA-1224。与对照菌株ATCC 17978相比，表达blaOXA-1224的重组菌株对亚胺培南和美罗培南的mic分别增加了8倍和16倍。酶测结果表明，OXA-1224对硝基烯烃具有较高的Km值，对亚胺培南（Km=496.7）和美罗培南（Km=126.1）具有较强的亲和力。与OXA-213相比，OXA-1224对亚胺培南和美罗培南的催化效率也有所提高。OXA-1224对亚胺培南（Km/Kcat=3.362）和美罗培南（Km/Kcat=4.837）的亲和力高于OXA-213 （Km/Kcat=2.469, Km/Kcat= 2.547）。然而，OXA-1224对第三代头孢菌素头孢他啶（ceftazime）的活性最小（Km>1000）。结论：新型β-内酰胺酶blaOXA-1224仅在体外对碳青霉烯类产生耐药性，与blaOXA-213相比，其mic值增加，对碳青霉烯类的催化效率更高。然而，它对头孢菌素的活性仍然有限。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Journal of Antimicrobial Agents 医学-传染病学

CiteScore

21.60

自引率

0.90%

发文量

176

审稿时长

36 days

期刊介绍： The International Journal of Antimicrobial Agents is a peer-reviewed publication offering comprehensive and current reference information on the physical, pharmacological, in vitro, and clinical properties of individual antimicrobial agents, covering antiviral, antiparasitic, antibacterial, and antifungal agents. The journal not only communicates new trends and developments through authoritative review articles but also addresses the critical issue of antimicrobial resistance, both in hospital and community settings. Published content includes solicited reviews by leading experts and high-quality original research papers in the specified fields.