FIG 1.

(a) Heatmap of the presence of the β-lactamase genes of all selected clinical A. baumannii strains. Due to the lack of a breakpoint for sulbactam alone, we chose ≤4 mg/liter as the temporary susceptibility breakpoint on the basis of the CLSI susceptibility breakpoint for ampicillin-sulbactam (≤8/4 mg/liter) in A. baumannii. On the basis of the breakpoint, all clinical isolates were divided into sulbactam-nonsusceptible or sulbactam-susceptible groups. Sul-S group, sulbactam-susceptible group; Sul-NS group, sulbactam-nonsusceptible group; A, bla_TEM-1; B, ISAba1-bla_ADC; C, bla_OXA-23; D, bla_OXA-58; E, bla_PER-1; F, bla_CARB-2. Red color represents positive, and the blue color represents negative. (b) Correlation of the characteristics of the bla_OXA-23 gene associated with sulbactam MIC. All the bla_OXA-23-positive strains were divided into two groups according to the transposase types carrying bla_OXA-23 or copy number of bla_OXA-23: Tn2009 and Tn2006, as well as single-copy group (copy number <1.5) and multicopy group (copy number >1.5).