Fig. 2

Relebactam restores the activity of imipenem in chromosomal AmpC–producing Enterobacterales isolates. A all (N = 13,003). B imipenem-NS (N = 1634). C imipenem-S (N = 11,369). Percentage represents n/N × 100%, where n was the number of isolates meeting the MIC threshold and N was the total number of isolates based on the CLSI 2021 clinical breakpoints for imipenem and imipenem/relebactam (both MIC ≤ 1 μg/mL for susceptibility) and subsequently categorized as either S (MIC ≤ 1 μg/mL) or NS (MIC > 1 μg/mL) [18]. The dashed line indicates the CLSI 2021 imipenem and imipenem/relebactam susceptibility breakpoints. The arrows indicate mode MIC values. Enterobacterales chromosomal AmpC–producing species included Enterobacter cloacae, Serratia marcescens, Klebsiella aerogenes, and Citrobacter freundii. AmpC, Ambler class C β-lactamase; CLSI, Clinical and Laboratory Standards Institute; MIC, minimum inhibitory concentration; NS, nonsusceptible; S, susceptible