The aim of this series of lectures and related seminars was, after seven years of teaching the discipline, to take stock of the evolution of microbiology and infectious diseases, and to identify trends in research progress and emerging medical issues, the integration of which would lead to the definition of a number of challenges structuring future lectures. These challenges can be summarized as follows.
Microbiology is becoming global. A pathogen can only infect a host in the context of predation on a niche often already occupied by a microbiota, i.e. a complex flora whose major balances, resilience and mechanisms it is vital to understand. This challenge was further illustrated by the organization of an international symposium entitled "Communication among complex microbial populations and their host". Particular emphasis was placed on understanding the mechanisms of competition between microbes and the effectors dedicated to survival in this context: mechanisms of aggression, defense, metabolic competition, etc.