Aims: The aim was to evaluate the accuracy of direct disc susceptibility testing performed from positive BACTEC™ blood culture vials, using a pre-determined dilution protocol. Results were compared to those obtained by standard disc susceptibility testing according to CLSI methods.
Methods: Direct susceptibility testing was performed from 432 positive blood culture vials, generating 3829 antibiotic-organism results.
Results: When results were compared to the reference method, no very major error was detected. One (0.03%) major error and 89 (2.3%) minor errors were found. Error rates by organism-group ranged from 1.3% for Pseudomonas aeruginosa to 8.2% for beta-hemolytic streptococci.
Conclusions: Direct susceptibility testing provided accurate susceptibility results for most organism-antibiotic combinations, with the exception of the beta-hemolytic streptococci.
- disc diffusion
- susceptibility testing