Susceptibility Testing News

EUCAST method for rapid antimicrobial susceptibility testing (RAST) direct from blood culture bottles

EUCAST have published recommendations for short incubation (4, 6 and 8 hours) AST directly from positive blood culture bottles.
The method is available for bacteria that commonly cause bacteraemia, tested against antimicrobial agents commonly used to treat bloodstream infection:

  • Escherichia coli
  • Klebsiella pneumoniae
  • Pseudomonas aeruginosa
  • Staphylococcus aureus
  • Streptococcus pneumoniae
  • Enterococcus faecalis and Enterococcus faecium
  • Acinetobacter baumannii

The method was developed to use standard methodology, equipment and materials and to minimise the number of complicated steps:

  • The method consists of direct inoculation of disc diffusion plates (MH, MH-F) using 100 – 150 µL directly from a positive blood culture bottle.
  • No centrifugation or dilution of the inoculum is required – plates are inoculated as for standard EUCAST disc diffusion.

Results can be read after a shortened incubation (4, 6 and 8 hours), with breakpoints adapted to each incubation time.
Species identification must be known at the time of interpretation and dedicated RAST breakpoints must be used.
You can find more information on the EUCAST website: http://www.eucast.org/rapid_ast_in_blood_cultures/