Bianco Gabriele, Boattini Matteo, Comini Sara, Iannaccone Marco, Cavallo Rossana, Costa Cristina
Microbiology and Virology Unit, University Hospital Città della Salute e della Scienza di Torino, Turin, Italy.
Department of Public Health and Paediatrics, University of Turin, Turin, Italy.
J Antimicrob Chemother. 2022 May 29;77(6):1670-1675. doi: 10.1093/jac/dkac092.
To evaluate the performance of two rapid antimicrobial susceptibility testing (RAST) methods to determine ceftazidime/avibactam susceptibility directly from blood cultures (BCs).
A total of 246 Escherichia coli or Klebsiella pneumoniae isolates were tested for ceftazidime/avibactam susceptibility directly from BC bottles using EUCAST RAST and Etest® RAST. Results obtained after 4, 6 and 8 h of incubation were compared with those obtained by reference broth microdilution on pure overnight subcultures.
In total, the proportion of readable zones after 4 h of incubation was 96.7% and reached 100% after 6 and 8 h of incubation. EUCAST RAST yielded >98% of categorical agreement (CA) with all reading times. Major error (ME) and very major error (VME) rates were inferior to 3%, for each of the reading times. The proportion of results in the area of technical uncertainty (ATU) was almost similar (3.8%-4.1%) at the different reading times. DET-RAST yielded 97.5%, 98% and 99.6% of CA with readings at 4, 6 and 8 h, respectively. One (0.6%) ME was observed at each reading time, whereas five (5.9%) and four (4.5%) VMEs were observed analysing readings at 4 and 6 h, respectively. No VME was observed with readings at 8 h.
EUCAST RAST was accurate to determine ceftazidime/avibactam susceptibility of carbapenemase-producing K. pneumoniae and E. coli directly from BC bottles. DET-RAST has the advantage of determining MIC values and avoiding ATU results but showed to be an accurate method only with reading at 8 h.
评估两种快速抗菌药物敏感性试验（RAST）方法直接从血培养（BC）中确定头孢他啶/阿维巴坦敏感性的性能。
使用欧盟CAST RAST和Etest® RAST直接从BC瓶中对总共246株大肠埃希菌或肺炎克雷伯菌分离株进行头孢他啶/阿维巴坦敏感性测试。将孵育4、6和8小时后获得的结果与通过参考肉汤微量稀释法对过夜纯传代培养物获得的结果进行比较。
总体而言，孵育4小时后可读区域的比例为96.7%，孵育6和8小时后达到100%。在所有读取时间，欧盟CAST RAST的分类一致性（CA）均>98%。每个读取时间的主要误差（ME）和极主要误差（VME）率均低于3%。在不同读取时间，技术不确定区域（ATU）的结果比例几乎相似（3.8%-4.1%）。DET-RAST在4、6和8小时读取时的CA分别为97.5%、98%和99.6%。在每个读取时间观察到1例（0.6%）ME，而在分析4和6小时读取结果时分别观察到5例（5.9%）和4例（4.5%）VME。在8小时读取时未观察到VME。
欧盟CAST RAST可准确直接从BC瓶中确定产碳青霉烯酶肺炎克雷伯菌和大肠埃希菌对头孢他啶/阿维巴坦的敏感性。DET-RAST具有确定最低抑菌浓度（MIC）值并避免ATU结果的优势，但仅在8小时读取时才是一种准确的方法。
