Demirocak Faruk, Langerak Diana, Yusuf Erlangga
Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands.
Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands.
J Glob Antimicrob Resist. 2025 Mar;41:211-215. doi: 10.1016/j.jgar.2024.12.028. Epub 2025 Jan 14.
Piperacillin/tazobactam antimicrobial susceptibility testing (AST) against Enterobacterales can be challenging. The aim of this study was to assess the reproducibility of various automated (VITEK 2) and nonautomated AST methods (broth microdilution (BMD), minimum inhibitory concentration (MIC) test strip, and disk diffusion) for piperacillin/tazobactam in 'challenging' E. coli isolates.
We performed 20 repeated ASTs for seven clinical E. coli isolates: Two resistant to piperacillin/tazobactam but susceptible to amoxicillin/clavulanic acid, four isolates with various β-lactamase coding genes (two bla, one bla, and one with plasmidal bla), and one isolate where VITEK 2 initially could not produce MIC measurements for piperacillin/tazobactam (i.e. no results generated).
Upon repetition, the same MIC as the mode value (i.e. the most frequent MIC value of each AST method) was found between 21% and 87% (BMD), 46% and 100% (VITEK 2), and 48% and 100% (gradient test) of the repetitions. The range of essential agreement percentage (i.e. ±1 doubling dilution from this mode value) was 53-100% (BMD), 63-100% (VITEK 2), and 100% (gradient test). Percent categorical agreement (same susceptible of resistant category using EUCAST breakpoint v. 14.0) was 71-100% (BMD), 85-92% (VITEK 2), 76-100% (gradient test) and 100% (disk diffusion).
In conclusion, this study provides insight on the reliability of AST results for piperacillin/tazobactam in challenging E. coli isolates. While the results indicate that most methods are generally reproducible, certain isolates may present inconsistent MIC results.
对肠杆菌科细菌进行哌拉西林/他唑巴坦抗菌药物敏感性试验（AST）可能具有挑战性。本研究的目的是评估各种自动化（VITEK 2）和非自动化AST方法（肉汤微量稀释法（BMD）、最低抑菌浓度（MIC）试纸条法和纸片扩散法）对“具有挑战性的”大肠杆菌分离株进行哌拉西林/他唑巴坦AST的可重复性。
我们对7株临床大肠杆菌分离株进行了20次重复AST试验：2株对哌拉西林/他唑巴坦耐药但对阿莫西林/克拉维酸敏感，4株带有各种β-内酰胺酶编码基因（2株bla，1株bla，1株带有质粒bla），以及1株VITEK 2最初无法得出哌拉西林/他唑巴坦的MIC测量值（即未产生结果）的分离株。
重复试验时，在各AST方法重复试验的21%至87%（BMD）、46%至100%（VITEK 2）以及48%至100%（梯度试验）中发现与众数MIC值（即每种AST方法中最常见的MIC值）相同的MIC。基本一致率范围（即从此众数MIC值起±1个稀释倍数）为53% - 100%（BMD）、63% - 100%（VITEK 2）和100%（梯度试验）。分类一致率（使用EUCAST 14.0版折点判定相同的敏感或耐药类别）为71% - 100%（BMD）、85% - 92%（VITEK 2）、76% - 100%（梯度试验）和100%（纸片扩散法）。
总之，本研究为具有挑战性的大肠杆菌分离株中哌拉西林/他唑巴坦AST结果的可靠性提供了见解。虽然结果表明大多数方法通常具有可重复性，但某些分离株可能会出现不一致的MIC结果。
