Comparison of ceftazidime-avibactam susceptibility testing methods against OXA-48-like carrying Klebsiella blood stream isolates

Ceftazidime-avibactam exhibits good in vitro activity against carbapenem resistant Klebsiella (CRK) carrying OXA-48-like enzymes. We tested two hundred unique CRK blood stream isolates (71% with single OXA-48-like carbapenemases, including OXA-48, n=62; OXA-232, n=57; OXA-244, n=17; OXA-181, n=5) that were collected as part of a multicentre study against ceftazidime-avibactam using Etest (bioMérieux, Marcyl’Étoile, France), 10/4 μg disc (Thermo Fisher) and Sensititre Gram Negative EURGNCOL Plates (Lyophilized panels, Sensititre, Thermo Fisher) with the aim of comparing the performances of the Etest and disc to that of Sensititre. Ceftazidime-avibactam MIC50/90 was 2/>16 mg/L for the entire collection and was 2/4 mg/L for single OXA-48-like producers. Categorical and essential agreements between the Etest and Sensititre were 100% and 97%, respectively. Categorical agreement between the disc and Sensititre was 100%. Etest and 10/4 μg discs are suitable alternatives to Sensititre for ceftazidime-avibactam sensitivity testing for OXA-48-like producers.