FIG 1.

MIC distributions and relationship between colistin (COL) resistance and azithromycin (AZM) susceptibility. Dashed lines delineate the CLSI susceptible breakpoints for each respective drug. (A) MICs for both COL (left) and AZM (right) were determined against 77 carbapenem-resistant A. baumannii (CRAB) clinical isolates using either MHII or RPMI 1640 media. The MHII and RPMI data points lie to the left or right, respectively, of their assigned x axis tick mark. (B) Per the CDC-FDA AR Isolate Bank, the sequenced strains tested here harbored either both the macrolide resistance genes mphE and msrE or neither. The panel labeled “Harbors macR gene” includes only strains that harbor both mphE and msrE (n = 50 carbapenem-resistant clinical isolates for MHII; n = 45 carbapenem-resistant clinical isolates for RPMI). (C) MICs performed in traditional MHII medium (n = 81 clinical isolates; 77 carbapenem-resistant and 4 carbapenem-susceptible isolates).