64 Facultative Intracellular Bacteria

Question 1

What are the benefits of living intracellularly?

Answer 1

Avoids host defenses; easy way to be transported around the animal

Question 2

How do bacteria avoid being killed after phagocytosis?

Answer 2

-Inhibition of phagosome-lysosome fusion
-Escapes phagosome
-Persist despite phagosome-lysosome fusion (inactivate ROS)

Question 3

Immunity against facultative intracellular bacteria is primarily _____ (innate/cellular/humoral).

Answer 3

Cellular (macrophages and NK cells)

Question 4

Listeria is gram (+/-)

Answer 4

Positive

Question 5

Describe the motility of listeria inside and outside of the host.

Answer 5

Outside host – lower temps; uses flagella
Inside host – higher temps; hijacks actin of the epithelial cell to use actin polymerization and propulsion (ActA).

Question 6

What species are most frequently affected by listeria?

Answer 6

Ruminants

Question 7

What does listeria cause in infected animals?

Answer 7

Septicemia, encephalitis, and abortions

Question 8

Describe the intestinal pathogenesis of listeria.

Answer 8

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

Question 9

Describe the CNS pathogenesis of listeria.

Answer 9

Enters via damaged oral/nasal/ocular mucosa, invades neural sheath of peripheral nerve (trigeminal nerve), invades CNS

Question 10

What is a classical CNS sign of listeria?

Answer 10

Circling disease, typically circling in the same direction

Question 11

What is the primary reservoir of yersinia pestis?

Answer 11

Rodents

Question 12

What domestic animal is most commonly affected by plague?

Answer 12

Cats

Question 13

What are the 3 types of plague?

Answer 13

Bubonic plague (local lymphadenitis)
Pneumonic plague (pneumonia)
Septicemic plague (septicemia)

Question 14

What is the main vector of plague?

Answer 14

Fleas (oriental rat fleas)

Question 15

Starting in the flea, describe the pathogenesis of plague.

Answer 15

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

Question 16

What are the functions of the virulence factors in early vs late plague infection?

Answer 16

Early – invade and replicate
Late – survive extracellularly

Question 17

What are the clinical signs of plague?

Answer 17

Regional lymphadenitis (often mandibular), fever, depression, anorexia, sneezing, cough, CNS disturbances, tonsilitis, cranial and cervical edema, pneumonia

Question 18

What is the causitive agent of tularemia?

Answer 18

Francisella tularensis

Question 19

How is tularemia transmitted?

Answer 19

Aerosol, vectors (ticks), ingestion of contaminated food/water

Question 20

What are the reservoirs of tularemia?

Answer 20

Lagomorphs, rodents, amoebae

Question 21

What domestic animal is most commonly affected by tularemia?

Answer 21

Cats

Question 22

Describe the pathogenesis of tularemia.

Answer 22

Infection (bite, inhalation, ingestion) –> uptake, survival, and replication in local phagocytes –> colonize to regional LNs –> granulomatous inflammation

Question 23

Describe the morphology of Brucella.

Answer 23

Non-motile G- coccobacilli

Question 24

What is unique about brucella peptidoglycan layer?

Answer 24

It’s very prominent

Question 25

Is brucella an obligate pathogen?

Answer 25

Yes

Question 26

What are the 3 most important zoonotic species of brucella?

Answer 26

B. melitensis, B. abortus, B. suis

Question 27

What are some clinical signs of brucella?

Answer 27

Abortion, epididymitis, and orchitis

Question 28

Describe the pathogenesis of brucella.

Answer 28

Organism penetrates INTACT mucosal surfaces –> uptake by macrophages –> intracellular survival –> hematogenous dissemination –> localization to the reticuloendothelial system and repro tract

Question 29

How does brucella cause abortions?

Answer 29

Interference with fetal circulation via placentitis, endotoxin, and fetal stress (inflammation)

Question 30

What is a brucellosome?

Answer 30

An acidified vacuole that brucella survives in to traffic it to the ER so it can replicate in ER-derived vacuoles

Question 31

What is the name of the disease caused by brucella in humans?

Answer 31

Undulant fever