Dr Ehrlich counts among his contributions to science the re-writing of much of our understanding of chronic bacterial pathogenesis. This began with his promulgation of the biofilm paradigm to explain many facets of chronic mucosal microbial infections, an area of interest for nearly a quarter of a century. This work originated with his explorations into the pathogenesis of chronic middle-ear disease in children. Subsequently, has has repeatedly generalized and expanded this concept such that it is now widely accepted that the vast majority of all chronic microbial infections are biofilm-associated. He also advanced the Distributed Genome Hypothesis to explain the enormous clinical variability among strains of a bacterial species, which together with the biofilm paradigm form the bases for his rubric of Bacterial Plurality. More recently he has developed the concept of bacterial population-level virulence factors and has used statistical genetics and machine learning methods for the first time within the field of bacterial genomics to identify distributed genes that are associated with virulence. This computational methodology provides a non-biased, top-down approach to prioritize the annotation of hypothetical genes.