Table_1_In Vitro Activity Comparison of Ceftazidime–Avibactam and Aztreonam–Avibactam Against Bloodstream Infections With Carbapenem-Resistant Organisms in China.docx

ObjectivesThe aim of this work was to investigate the activity of ceftazidime–avibactam (CZA) and aztreonam–avibactam (AZA) against bloodstream infections caused by carbapenem-resistant organisms (CROs).
MethodsNon-duplicate CROs, including 56 carbapenem-resistant Escherichia coli (CR-Eco), 318 carbapenem-resistant Klebsiella pneumoniae (CR-Kpn), and 65 carbapenem-resistant Pseudomonas aeruginosa (CR-Pae), were collected using the Blood Bacterial Resistant Investigation Collaborative System (BRICS) program in China. The minimum inhibitory concentrations (MICs) of 24 antibiotics were tested. Carbapenemase genes were amplified for CZA-resistant CROs by PCR. The MICs of CZA and AZA were further determined with avibactam at 8 and 16 mg/L, respectively.
ResultsThe resistance rate of polymyxin B against CROs was less than 5%. Only one CR-Kpn was resistant to tigecycline. The resistance rates of CZA against CR-Eco, CR-Kpn, and CR-Pae were 75.0%, 12.6%, and 18.5%, respectively. The MIC90 values of AZA against CR-Eco, CR-Kpn, and CR-Pae were 2/4, 1/4, and 64/4 mg/L, respectively. Among the CZA-resistant CROs, 42 (100%) CR-Eco, 24 (60%) CR-Kpn, and 1 (8.3%) CR-Pae isolates harbored metallo-β-lactamase genes. The increase of avibactam concentration enhanced the susceptibility of CZA and AZA against CROs, especially for CR-Eco and CR-Kpn.
ConclusionsThe in vitro activity of AZA was superior to that of CZA against CR-Eco and CR-Kpn, whereas CZA showed better effect against CR-Pae.

研究目的：本研究旨在探究头孢他啶-阿维巴坦（ceftazidime–avibactam, CZA）与氨曲南-阿维巴坦（aztreonam–avibactam, AZA）对碳青霉烯类耐药菌（carbapenem-resistant organisms, CROs）引发血流感染的抗菌活性。
研究方法：采用中国血液细菌耐药性调查协作系统（Blood Bacterial Resistant Investigation Collaborative System, BRICS）项目收集非重复分离的碳青霉烯类耐药菌，包括56株碳青霉烯类耐药大肠埃希菌（carbapenem-resistant Escherichia coli, CR-Eco）、318株碳青霉烯类耐药肺炎克雷伯菌（carbapenem-resistant Klebsiella pneumoniae, CR-Kpn）以及65株碳青霉烯类耐药铜绿假单胞菌（carbapenem-resistant Pseudomonas aeruginosa, CR-Pae）。检测24种抗菌药物的最低抑菌浓度（minimum inhibitory concentrations, MICs）；通过聚合酶链式反应（polymerase chain reaction, PCR）扩增CZA耐药碳青霉烯类耐药菌的碳青霉烯酶基因（carbapenemase genes）；进一步分别以8mg/L和16mg/L浓度的阿维巴坦增效，测定CZA与AZA的最低抑菌浓度。
研究结果：多黏菌素B对碳青霉烯类耐药菌的耐药率低于5%；仅1株CR-Kpn对替加环素耐药。CZA对CR-Eco、CR-Kpn及CR-Pae的耐药率分别为75.0%、12.6%及18.5%。AZA对CR-Eco、CR-Kpn及CR-Pae的MIC90值分别为2/4、1/4及64/4 mg/L。在CZA耐药的碳青霉烯类耐药菌中，42株（100%）CR-Eco、24株（60%）CR-Kpn以及1株（8.3%）CR-Pae携带金属β-内酰胺酶基因（metallo-β-lactamase genes）。阿维巴坦浓度升高可增强CZA与AZA对碳青霉烯类耐药菌的抗菌活性，尤其对CR-Eco和CR-Kpn效果显著。
结论：体外抗菌实验显示，AZA对CR-Eco与CR-Kpn的抗菌活性优于CZA，而CZA对CR-Pae的抗菌效果更佳。