The software model 'Micro-Gen' simulates the growth and development of cultured bacterial cells and their interactions with antimicrobial drugs. It uses an agent-based modelling approach, which means that pre-defined rules and parameters for each bacterium can be set, and emergent properties of the colony examined, without the need for population-level laws. The model reproduces accurately the standard growth curve characteristic of bacterial colonies grown in batch culture in the laboratory. It also successfully reproduces the effects of bacteriostatic and bactericidal antibiotics on the growth of the bacterial colony. The model provides a robust platform for incorporating knowledge of the cellular mechanics of individual bacterial cells into an overall model of heterogeneous bacterial population dynamics.