Colistin susceptibility testing and Vitek-2™: is it really useless?

- P. aeruginosa isolates showed high rates of major errors, whereas for A. baumannii isolates, high rates of very major errors were obtained.
- The Vitek-2 automated method does not show reliable results when evaluating Enterobacter spp.
- For isolates with borderline MICs (between 1 and 8), the results obtained by Vitek-2 should be confirmed for all bacterial species.
- For K. pneumoniae and E. coli, a good correlation was obtained between the results of Vitek-2 and broth microdilution when evaluated with isolates with ≤0.5 and ≥16 MICs.