In nearly four decades, P. Cossart and her group using several multidisciplinary approaches and cutting edge technologies have unveiled an impressive number of sophisticated mechanisms used by the bacterial pathogen Listeria monocytogenes to survive in the environment and/or infect mammals. Their results have led to a series of new concepts in fundamental microbiology- in particular RNA mediated regulation-, in infection biology, in cell biology and also in epigenetics, paving the way to the understanding of thre basis of many other infections. An historical perspective with most striking findings will be presented.