Wang Guangfen, Zhang Hui, Wu Qiaoping, Xu Jianqiang, Qiu Xuedan, Chen Jinyuan, Cui Fujie, Zhou Jian, Li Qingcao
Department of Hospital Infection-Control, The Affiliated Li Huili Hospital, Ningbo University, Ningbo, China.
Department of Clinical Laboratory, Ninghai County Chengguan Hospital, Ningbo, China.
Front Microbiol. 2025 Mar 20;16:1542029. doi: 10.3389/fmicb.2025.1542029. eCollection 2025.
This study aims to investigate the synergistic effects and biofilm inhibition mechanisms of ceftazidime-avibactam (CZA) combined with aztreonam (ATM) against carbapenem-resistant a (CRKP) commonly found in the local clinical setting, providing new insights for clinical anti-infective strategies.
We selected a total of 150 non-duplicate clinical isolates of CRKP from multiple hospitals in Ningbo. Common carbapenemase genes were detected using PCR. Broth microdilution and time-kill assays were used to evaluate the synergistic effects of CZA and ATM, both individually and in combination, on CRKP isolates with different enzyme types, and the fractional inhibitory concentration index (FICI) was calculated. The crystal violet staining method and bacterial cell permeability assay were employed to assess the impact of CZA, ATM, and their combination on the cell structure and biofilm formation capacity of CRKP. Real-time quantitative PCR (qRT-PCR) was used to measure the expression levels of biofilm-related genes (, , , , and ) in CRKP under treatment with CZA, ATM, or their combination.
The comparison of synergistic indices for different enzyme-type CRKP strains with CZA and ATM combination therapy showed a statistically significant difference ( < 0.01). The time-kill assay indicated that the time-kill curves for strains carrying and resistance genes were similar between the monotherapy and combination therapy groups, while the CZA + ATM combination therapy group showed a significant decrease in bacterial concentration after 4-8 h of cultivation compared to the CZA and ATM monotherapy groups. The crystal violet staining and bacterial cell permeability assays demonstrated that the CZA + ATM combination significantly reduced biofilm formation and increased cellular structure disruption in CRKP. The qRT-PCR results showed that CZA combined with ATM notably decreased the expression levels of biofilm-related genes , , , , and in CRKP.
The combination of ATM and CZA shows a strong synergistic antibacterial effect against CRKP strains with various enzyme types, with particularly notable synergy in strains carrying the resistance gene. Additionally, this combination significantly disrupts the cellular structure of CRKP and inhibits biofilm formation.
本研究旨在探讨头孢他啶-阿维巴坦（CZA）联合氨曲南（ATM）对当地临床常见的耐碳青霉烯类肺炎克雷伯菌（CRKP）的协同作用及生物膜抑制机制，为临床抗感染策略提供新的见解。
我们从宁波多家医院共选取了150株非重复的CRKP临床分离株。采用PCR检测常见的碳青霉烯酶基因。采用肉汤微量稀释法和时间杀菌试验评估CZA和ATM单独及联合使用对不同酶型CRKP分离株的协同作用，并计算部分抑菌浓度指数（FICI）。采用结晶紫染色法和细菌细胞通透性试验评估CZA、ATM及其联合使用对CRKP细胞结构和生物膜形成能力的影响。采用实时定量PCR（qRT-PCR）检测CZA、ATM或其联合处理下CRKP中生物膜相关基因（、、、、和）的表达水平。
不同酶型CRKP菌株CZA与ATM联合治疗的协同指数比较差异有统计学意义（<0.01）。时间杀菌试验表明，携带和耐药基因的菌株在单药治疗组和联合治疗组之间的时间杀菌曲线相似，而CZA+ATM联合治疗组在培养4-8小时后细菌浓度比CZA和ATM单药治疗组显著降低。结晶紫染色和细菌细胞通透性试验表明，CZA+ATM联合使用显著减少了CRKP生物膜的形成，并增加了细胞结构的破坏。qRT-PCR结果表明，CZA联合ATM显著降低了CRKP中生物膜相关基因、、、、和的表达水平。
ATM与CZA联合使用对各种酶型的CRKP菌株显示出强大的协同抗菌作用，在携带耐药基因的菌株中协同作用尤为显著。此外，这种联合使用显著破坏了CRKP的细胞结构并抑制了生物膜的形成。
