64 Facultative Intracellular Bacteria Flashcards
What are the benefits of living intracellularly?
Avoids host defenses; easy way to be transported around the animal
How do bacteria avoid being killed after phagocytosis?
-Inhibition of phagosome-lysosome fusion
-Escapes phagosome
-Persist despite phagosome-lysosome fusion (inactivate ROS)
Immunity against facultative intracellular bacteria is primarily _____ (innate/cellular/humoral).
Cellular (macrophages and NK cells)
Listeria is gram (+/-)
Positive
Describe the motility of listeria inside and outside of the host.
Outside host – lower temps; uses flagella
Inside host – higher temps; hijacks actin of the epithelial cell to use actin polymerization and propulsion (ActA).
What species are most frequently affected by listeria?
Ruminants
What does listeria cause in infected animals?
Septicemia, encephalitis, and abortions
Describe the intestinal pathogenesis of listeria.
Ingested; most are killed by gastric acid. Attaches, enters, and survives in epithelial cells, M cells, and phagocytes. Dissemimnates between cells, through the bloodstream, and via phagocytes
Describe the CNS pathogenesis of listeria.
Enters via damaged oral/nasal/ocular mucosa, invades neural sheath of peripheral nerve (trigeminal nerve), invades CNS
What is a classical CNS sign of listeria?
Circling disease, typically circling in the same direction
What is the primary reservoir of yersinia pestis?
Rodents
What domestic animal is most commonly affected by plague?
Cats
What are the 3 types of plague?
Bubonic plague (local lymphadenitis)
Pneumonic plague (pneumonia)
Septicemic plague (septicemia)
What is the main vector of plague?
Fleas (oriental rat fleas)
Starting in the flea, describe the pathogenesis of plague.
Flea bloodmeal from infected host –> bacterial colony blocks the flea’s proventriculus/contaminates feeding site –> bacteria transmitted at next bloodmeal –> bacteria enters host; most killed by PMNs and infl –> surviving bacteria live intracellular and secrete antiphagocytic and antiinflammatory proteins –> progresses to extracellular bacterial survival by changing virulence factors expressed
What are the functions of the virulence factors in early vs late plague infection?
Early – invade and replicate
Late – survive extracellularly
What are the clinical signs of plague?
Regional lymphadenitis (often mandibular), fever, depression, anorexia, sneezing, cough, CNS disturbances, tonsilitis, cranial and cervical edema, pneumonia
What is the causitive agent of tularemia?
Francisella tularensis
How is tularemia transmitted?
Aerosol, vectors (ticks), ingestion of contaminated food/water
What are the reservoirs of tularemia?
Lagomorphs, rodents, amoebae
What domestic animal is most commonly affected by tularemia?
Cats
Describe the pathogenesis of tularemia.
Infection (bite, inhalation, ingestion) –> uptake, survival, and replication in local phagocytes –> colonize to regional LNs –> granulomatous inflammation
Describe the morphology of Brucella.
Non-motile G- coccobacilli
What is unique about brucella peptidoglycan layer?
It’s very prominent
Is brucella an obligate pathogen?
Yes
What are the 3 most important zoonotic species of brucella?
B. melitensis, B. abortus, B. suis
What are some clinical signs of brucella?
Abortion, epididymitis, and orchitis
Describe the pathogenesis of brucella.
Organism penetrates INTACT mucosal surfaces –> uptake by macrophages –> intracellular survival –> hematogenous dissemination –> localization to the reticuloendothelial system and repro tract
How does brucella cause abortions?
Interference with fetal circulation via placentitis, endotoxin, and fetal stress (inflammation)
What is a brucellosome?
An acidified vacuole that brucella survives in to traffic it to the ER so it can replicate in ER-derived vacuoles
What is the name of the disease caused by brucella in humans?
Undulant fever
