Abstract:Brucella organisms are facultative intracellular bacteria capable of surviving inside professional and non-professional phagocytes. Upon cell contact the bacteria is internalized via receptor molecules. Once inside cells, Brucella localizes in early phagosomes, where it avoids fusion with late endosomes and lysosomes. Then, the bacterium redirects its trafficking to autophagosomes and finally reaches the endoplasmic reticulum, the replicating niche. Once inside the endoplasmic reticulum, Brucella extensively replicates without restricting basic cellular functions or inducing damage to cells. Invasion, intracellular trafficking and replication of Brucella organisms in professional and non-professional phagocytes and the molecular determinants involving Brucella intracellular life are reviewed in this article.