Method for evaluating antibiotic susceptibility

A method for determining a minimum inhibitory concentration (MIC) to an antimicrobial drug for a bacteria culture in a container , the method comprising calculating for each well a third derivative of said detected intensity in a first time frame and in a second time frame, said second time frame being subsequent, preferably directly subsequent, to said first time frame; comparing said third derivative of the detected intensity in both said time frames to one or more threshold values; determining a first MIC value based on said comparison of said third derivative in said first time frame to said one or more threshold values, and determining a second MIC value based on said comparison of said third derivative in said second time frame to said one or more threshold values; and determining from said first and said second MIC values the MIC value of said bacteria culture.