Obligate intracellular parasites Intracellular existence protects bug from B-cell defenses Cannot be cultured on inert media Bacteria Chlamydia spp. cannot make any ATP Rickettsia spp. cannot make enough ATP Mycobacterium leprae Viruses all viruses are obligate intracellular parasites Protozoa Plasmodium spp. Toxoplasma gondii Babesia spp. Leishmania donovani Trypanosoma cruzi Fungi none Facultative intracellular parasites Able to live and reproduce either inside or outside of cells Bacteria Mycobacterium tuberculosis Salmonella typhi Francisella tularensis Listeria monocytogenes Legionella pneumophila MOTTS Brucella spp. Neisseria spp. Yersinia pestis Nocardia spp. Fungi Histoplasma capsulatum Helminths Enterobius vermicularis Other obligate parasites Cannot be cultured on inert media Found outside cells Bacteria Treponema pallidum Fungus (yeast-like) Pneumocystis jiroveci