Intracellular Bacteria Flashcards
Bacterial intracellular pathogens may be
facultative or obligate
what are facultative intracellular bacteria? which ones function this way?
divide independently and on agar, but enter host cells as part of pathogenesis (neisseria, enterics, mycobacter, bacilli, and legionella
What are obligate intracellular parasites? Give examples?
require host cell resources to multiply; rickettsial, chlamydia
How are obligate intracellular parasites grown in culture?
Grown in tissue culture like viruses
How does intracellular pathogenesis work?
Allows human pathogens to use infected macrophages for transport around the body and evade humoral and surface innate immunity (actin based cell-cell spread)
What is a common theme among intracellular virulence factors?
Type 3 secretion sytems
What are the 2 major functions of T3SS?
Enhance phagocytosis by target cell type or alter the endosome so that lysosomes can’t fuse
Why are tetracyclines the first choice in treating intracellular bacteria?
must be effective against bacteria that replicate inside cell, so must be able to penetrate human cell membrane and remain active/ able to activate after doing so
What is listeria monocytogenes?
Facultative intracellular bacterium that causes gastroenteritis when it contaminates cold-stored pre-prepared foods.
What diseases can it cause and in what population?
Immunosuppressed and pregnant women are at risk for dangerous disease, particularly meningitis; complicates pregnancy
How does listeria infect host?
after endocytosis, escapes the endosome and uses actin-based motility to spread between cells
Rickettsia rickettsiae is
obligate intracellular pathogen vectored to humans by ticks
How does rickettsia infect host?
infects endothelium of blood vessels and causes leakage
What major disease does rickettsia cause?
Rocky mountain spotted fever
What virulence factors does rickettsia hold?
factors for adhesion, cell entry, endosomal escape, and actin based cell-cell spread
Chlamydia is special because
it has unusual obligate-intracellular replication strategy featuring tiny, infectious,rugged elementary bodies that unpack into larger delicate reticular bodies after cell penetration
What does chlamydia carry T3SS for?
entry and establishing intracellular inclusion body
What happens to the reticulate bodies in the cells?
They multiply and convert back into elementary bodies as part of the intracellular inclusion body
What is a possible squelae of chylamydia?
reactive arthritis
Why must you always screen for chlamydia?
it may hide behind another infection on exam
Which is a greater risk in treating chlamydia: reinfection from untreated partners or antibiotic resistance?
re-infection from untreated partners
