Cells in the body have developed a variety of strategies toward removing harmful bacteria from the body. Phagocytosis is the uptake of large particles into cells typically utilized for the acquisition of nutrients. Phagocytosis is most often carried out by cells involved in the immune response, specifically macrophages and neutrophils.
Phagocytosis by macrophages is critical for uptake and degradation of infectious agents including bacteria. It is an extremely complex process that involves a variety of diverse structures and outcomes. There are some pathogens, including Salmonella typhimurium, Legionella pneumophila, and Mycobacterium tuberculosis that have evolved to have the ability to survive and even grow inside phagocytic cells.
Source: Annual Reviews of Immunology, Hack Dentistry