Failure of the Vitek AutoMicrobic system to detect beta-lactam resistance in Aeromonas species

Am J Clin Pathol. 1993 Sep;100(3):308-10. doi: 10.1093/ajcp/100.3.308.


The ability of the Vitek AutoMicrobic system (AMS; Vitek, Inc., Hazelwood, MO) and disk-diffusion method to detect beta-lactam resistance was assessed with 25 strains from four species of Aeromonas. A very major error was indicated when a strain was shown to be susceptible by the AMS or disk-diffusion method but resistant by the agar dilution method. The rates for very major errors for disk diffusion and the AMS were 0% and 43%, respectively. The beta-lactam agents and numbers of very major errors for the AMS were as follows: ticarcillin, 17; mezlocillin, 3; piperacillin, 4; cephalothin, 9; cefazolin, 3; cefoxitin, 1; cefotetan, 2; and cefuroxime, 1. Thus, these data suggest that the AMS currently is not reliable for testing the resistance of Aeromonas to beta-lactam agents.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aeromonas / drug effects*
  • Anti-Bacterial Agents / pharmacology*
  • Bacteriological Techniques / instrumentation*
  • Drug Resistance, Microbial
  • Microbial Sensitivity Tests
  • Reproducibility of Results
  • beta-Lactams


  • Anti-Bacterial Agents
  • beta-Lactams