Rapid antimicrobial susceptibility test, based on an analysis of changes in morphology and growth pattern of a microbial cell under different concentrations of various antimicrobial agents, and automated cell image analysis system therefor

An antimicrobial susceptibility test (AST) method based on an analysis of changes in morphology and growth pattern of microbial cells under an antimicrobial agent, wherein the AST method comprises the steps of:

• (A) exposing the microbial cells with the antimicrobial agent;
• (B) imaging the microbial cells exposed to the antimicrobial agent in (A) at least twice over time and comparing these images to measure a change in the total length of the cells, a change in the total area of the cells and a change in the total number of cells;
• (C) classifying the change in cellular morphology over time based on the measurement of (B) as follows:
• i) an increase in the total number of cells classifies the change in morphology as dividing;
• ii) an increase in the length of the cells classifies the change in morphology as filament formation;
• iii) an increase in the total area of the cells classifies the change in morphology as swelling formation;
• and
• iv) no increase in the total number, the total length, and total area of cells classifies the change in morphology as no change;
• (D) determining whether the microbial cells are resistant or susceptible to the antimicrobial agent as follows:
• i) microbial cells classified as dividing in step (C) are resistant to the antimicrobial agent;
• and
• ii) microbial cells classified as filament formation, swelling formation or no change are susceptible to the antimicrobial agent.