TABLE 3

Additional variables to be detailed when cAST method is gradient strip or disk diffusion method

ParameteraTesting considerationsData to be documented in study publication (if applicable)
MHA or supplemented MHAPerformance may vary across brands and lot numbers of MHABrand of MHA
Disks and gradient strips are typically developed with a single brand of MHANumber of lot numbers evaluated
Troubleshooting of MHA source if performance issues are noted (determining whether brand used is different from that used by gradient strip manufacturer)
Method used to determine MIC endpoints and management of colonies within zoneSome use a magnifying glass or digital camera/software for endpoint measurementMethod used to determine MIC endpoints, including managing any colonies within zone or equivocal endpoints
MIC values may differ depending on how colonies in the zone of growth inhibition are evaluatedAny procedure for rounding between 2-fold dilutions
Interpretation of endpoints may be challenging; follow manufacturer's instructions precisely (obtain photographs for guidance, if possible)
  • a MHA, Mueller-Hinton agar.