In vitro activity of aztreonam–avibactam against metallo-β-lactamase-producing Enterobacteriaceae—A multicenter study in China
Biying Zhang, Zhichen Zhu, Wei Jia, Fen Qu, Bin Huang, Bin Shan, Hua Yu, Yi‐Wei Tang, Liang Chen, Hong Du
Abstract
ObjectivesTo study the molecular epidemiology of clinical metallo-β-lactamase (MBL)-producing Enterobacteriaceae isolates in China and to evaluate the antimicrobial susceptibility of MBL-Enterobacteriaceae isolates to aztreonam–avibactam.MethodsBacterial speciation was determined using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. PCR was used to screen for common carbapenemase genes. Antimicrobial susceptibility testing of common clinical antibiotics and aztreonam–avibactam was performed using the standard broth microdilution method.ResultsA total of 161 MBL-Enterobacteriaceae isolates were included, with Klebsiella pneumoniae (n = 73, 45.4%) and Escherichia coli (n = 53, 32.9%) being the most common species. Among the 161 isolates, blaNDM (n = 151), blaIMP (n = 13), and blaVIM (n = 2) were detected, including five strains (3.1%) co-harboring two MBLs. MBL-Enterobacteriaceae isolates frequently contained two (n = 55, 34.2%) or more (n = 89, 55.3%) additional serine β-lactamase genes (blaKPC, blaCTX-M, blaTEM, or blaSHV). Antimicrobial susceptibility testing showed that 81.4% of isolates (n = 131) were resistant to aztreonam. The rates of resistance to cefazolin, ceftazidime, ceftriaxone, cefotaxime, ampicillin–sulbactam, amoxicillin–clavulanic acid, and piperacillin–tazobactam were all over 90%. The addition of avibactam (4 μg/ml) significantly reduced the minimum inhibitory concentrations (MICs) of the aztreonam-resistant isolates by more than 8-fold (range ≤0.125 to 4 μg/ml), with a MIC50/MIC90 of ≤0.125/1 μg/ml among the 131 isolates. Overall, 96.9% (n = 156) of the total isolates were inhibited at an aztreonam–avibactam concentration of ≤1 μg/ml. Univariate and multivariate logistic regression analysis found that in patients with MBL-Enterobacteriaceae infections, the presence of pre-existing lung disease (adjusted odds ratio 8.267, 95% confidence interval 1.925–28.297; p = 0.004) was associated with a hazard effect on worse disease outcomes.ConclusionsThe combined use of aztreonam–avibactam is highly potent against MBL-Enterobacteriaceae and may serve as a new candidate for the treatment of infections caused by MBL-Enterobacteriaceae in China.