In addition to host immunity, resident microbiota is shaping the ability of pathogens to invade and replicate in a host. To understand the interactions between pathogens themselves, I am involved in large-scale field observations that provide data characterizing the intra- and interspecific diversity between 20 sites in three countries over three years. Within the PATHOCOM project, my main focus is measuring the diversity of the background microbiota, quantifying the microbial load and describing inter-kingdom microbial community composition. Ultimately, this study aims to play a major role in predictive science.