Rapid AST in bloodcultures

Rapid AST directly from blood culture bottles

EUCAST will shortly publish recommendations for short incubation (4, 6 and 8 hours) AST directly from positive blood culture bottles using EUCAST standard disk diffusion. These are the characteristics of the rapid method:

  • direct inoculation of disk diffusion plates (MH, MH-F) using 100 - 150 ┬ÁL directly from a positive blood culture bottle (BD, bioMerieux and Thermo Fisher).
  • no centrifugation or dilution of the inoculum - inoculate plates as for standard EUCAST disk diffusion.
  • shortened incubation - 4, 6 and 8 hours with breakpoints adapted to each incubation time.
  • breakpoints for each species and each reading time.
  • identity of species must be known prior to interpretation of AST results.
  • the method is currently validated for the following species.

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

  • a positive blood culture bottle should be processed 0 - 18 hours after the positive signal.
  • zone diameters are read from the front of the plate after removal of the lid.
  • not all zone diameters can be read after 4 or 6 hours.
  • read zone diameters ONLY when an obvious zone edge can be identified - otherwise reincubate and read after 6 or 8 hours. 
  • the breakpoint table is specific for EUCAST Rapid AST - do not use the regular breakpoint table. Each species has its own TAB in the table and each reading time (4, 6 and 8 hours) its own section.

 Breakpoint table and method to be published before the end of November, 2018.