摘要目的:体外评估6种β-内酰胺类药物和3种β-内酰胺酶抑制剂组合对耐多药结核分枝杆菌（MTB）的抗菌活性，以期发现针对耐多药结核病最有效的β-内酰胺类药物和β-内酰胺酶抑制剂组合。方法:本研究自2020年1—9月共纳入来自河南省不同地区的105株耐多药MTB分离菌株，使用最低抑菌浓度（MIC）法测定6种β-内酰胺类药物（比阿培南、美罗培南、亚胺培南、多尼培南、厄他培南、泰比培南）单独或联合β-内酰胺酶抑制剂（克拉维酸、阿维巴坦、瑞来巴坦）对105株临床菌株的体外抗菌活性，使用PCR法和DNA测序分析 blaC、 ldt mt1和 ldt mt2的突变情况。使用卡方检验比较不同β-内酰胺类药物的抗菌活性。 结果:在本研究使用的几种β-内酰胺类药物中，泰比培南对耐多药MTB最为有效，MIC 50值为8 mg/L（χ 2=123.70， P=0.001）。阿维巴坦和瑞来巴坦与克拉维酸相比，可使大部分β-内酰胺类药物的MIC值明显降低。其中瑞来巴坦使泰比培南MIC 50和MIC 90均稀释了16倍，使23（21.90%）和41（39.04%）株的MIC稀释了32倍和16倍。共有13.33%（14/105）的菌株存在 blaC基因的突变，主要为3种替代突变，AGT333AGG、AAC638ACC和ATC786ATT。与同义突变组相比，克拉维酸-美罗培南组合对BlaC蛋白Ser111Arg和Asn213Thr突变菌株的MIC值明显降低。 结论:阿维巴坦和瑞来巴坦对β-内酰胺类药物协同作用均优于克拉维酸。泰比培南-瑞来巴坦组合对耐多药MTB具有最强的抗菌活性。BlaC蛋白Ser111Arg和Asn213Thr的突变可能增强了耐多药MTB对克拉维酸-美罗培南组合的敏感性。

abstractsObjective:To evaluate the activity of six β-lactams in combination with three β-lactamase inhibitors against mycobacterium tuberculosis(MTB) in vitro. Methods:A total of 105 multidrug-resistant tuberculosis (MDR-TB) strains from different regions of Henan province from January to September 2020 were included in this study. Drug activity of six β-lactams (biapenem, meropenem, imipenem, doripenem, ertapenem and tebipenem) alone or in combination with β-lactamase inhibitors (clavulanic acid, avibactam and relebactam) was examined by minimum inhibitory concentration method (MICs) against 105 clinical isolates. Mutations of blaC, ldt mt1 and ldt mt2 were analyzed by PCR and DNA sequencing. Chi-square test was used to compare the antimicrobial activities of different β-lactam drugs. Results:Out of the β-lactams used herein, tebipenem was the most effective against MDR-TB and had an MIC 50 value of 8 mg/L(χ 2=123.70, P=0.001). Besides, after the addition of β-lactamase inhibitors, the MICs of most β-lactam drugs were reduced more evidently in the presence of avibactam and relebactam compared to clavulanic acid.Especially, relebactam decreased both the MIC50 and MIC90 of telbipenem by 16-fold, and diluted the MIC of 23 (21.90%) and 41 (39.04%) isolatesby 32-fold and 16-fold.In addition, a total of 13.33% (14/105) of isolates harbored mutations in the blaC gene, with three different nucleotide substitutions: AGT333AGG, AAC638ACC and ATC786ATT. For the strains with Ser111Arg and Asn213Thr substitution in BlaC, the MIC values of the meropenem-clavulanate combination were reduced compared with a synonymous single nucleotide polymorphism (SNP) group. Conclusions:Both avibactam and relebactam had better synergistic effects on β-lactams than clavulanic acid. The combination of tebipenem and relebactam showed the most potent activity against MDR-TB isolates. In addition, the Ser111Arg and Asn213Thr substitution of BlaC may be associated with an increased susceptibility of MDR-TB isolates to meropenem in the presence of clavulanate.