Reproducibility of Ceftazidime/Avibactam MIC Results for Enterobacteriaceae and Pseudomonas aeruginosa Using MicroScan Dried Gram Negative MIC Panels

Abstract

Background. A multicenter study was performed to evaluate the reproducibility of Ceftazidime/Avibactam on a MicroScan Dried Gram Negative MIC (MSDGN) Panel. Materials/Methods. MSDGN panels were evaluated for reproducibility at three sites. For reproducibility, a total of 16 on-scale organisms were tested on MSDGN panels at each site (13 Enterobacteriaceae and 3 Pseudomonas aeruginosa). Three replicates of each organism were tested each day for three days using the turbidity and PromptTM∗ methods of inoculation. MSDGN panels were incubated at 35 ± 2°C and read on the WalkAway System, the autoSCAN-4 instrument, and read visually. Read times for the MSDGN panels were at 16-20 hours. FDA breakpoints (μg/mL) used for interpretation of MIC results were: Enterobacteriaceae ≤ 8/4 S and ≥ 16/4 R; P. aeruginosa ≤ 8/4 S and ≥ 16/4 R. Results. Reproducibility among the three sites was greater than 95% for all read methods for both the turbidity and Prompt inoculation methods. Conclusion. This multicenter study showed that Ceftazidime/Avibactam MIC results for Enterobacteriaceae and P. aeruginosa obtained with the MSDGN panel are highly reproducible. (Table Presented).