Flashcards in 1-21 Intracellular Bacteria Deck (11)
what is unusual about chlamydia replication cycle?
has two morphs: reticulate and elementary bodies
Explain the difference between obligate and facultative intracellular pathogens and the relevance of these terms to laboratory diagnosis of infection.
Obligate intracellular pathogens need a host cell to multiply
facultative intracellular pathogens grow and multiply independently, but enter the host cell as part of their pathogenesis.
Obligate intracellular pathogens must be grown in tissue culture.
List the three major pathways by which intracellular pathogens survive endocytosis to establish infection.
Upon entering the host cell, intracellular pathogens can do the following:
Escape the endosome (break out before fusion with a lysosome)
Subvert the endosome (prevent lysosome fusion)
Survive lysosome fusion (live in the environment of the endolysosome)
5 major recurring themes in intracellular pathogensis
1. use of infected macrophages for transport
2. Host cell takeover by type III secretion system
3.actin based motility and cell-cell spread
4. evasion of humoral immunity
5. need for antibiotics to penetrate human cell membrane
example of use of infected macrophages for transport
salmonella is engulfed by macrophage, uses it as trojan horse to get around the body
example of host cell takeover by type 3 secretions systems
either enhances phagocytosis in target cell type
alters the phagosome so that the lysosome fails to fuse
actin-based motility and cell-cell spread
listeria - polymerizes actin (using ActA virulence factor) and uses it for motility and to break out of cell to cell-cell penetrate adjacent cell
evasion of humoral immunity
pathogen uses variety of mechanisms to avoid being neutralized by host humoral immunity
enteric bacteria using M cells as gateways to exterior surface of intestine,
the need for antibiotics to penetrate human cell membrane
in order to reach the intracelluar pathogens within the cells, antibiotics must be able to get to them
antibiotics for intracellular?
azith or chloramphenicol if pregnant