Bacterial Intracellular Pathogens

Question 1

Listeria Pathogenesis

Answer 1

• Contaminates dairy and processed meats (particularly hotdogs)
• Binds to surface of cells E-cadherin in GI tract
  *triggers signal transduction at the membrane level and activation of enzymes at the membrane level; PI3 kinase gets activated- leads to phosphorylation events that are influencing the cytoskeleton triggering a response of the cell to engulf it
• Picks up eukaryotic cells actin molecules which it uses to move from the apical layer to the submucosal
• Gains access to bloodstream engulfed by a lymphocyte; induces the lymphocyte to express adhesion molecules on its surface- becomes more “sticky” to endothelial cells
• Can then cause systemic infection

Question 2

Listeria infection

Answer 2

• Can cause meningitis
• Can get through placenta and kill the fetus

Question 3

Examples of evasion and representative bacteria

Answer 3

• No triggering of oxidative burst
• Modify or abort normal route of phagosome maturation
• Diversion of phagosome to another pathway and resist phagolysosomal fusion
• Resist lysosomal degradation
• Escape from phagosome

Question 4

Coxiella burnetii pathogenesis

Answer 4

• Rickettsiaceae bacteria
• Cause acute and chronic Q fever
• Inhalation- airborne particles from livestock, cats, dogs degradation and formation of immune complexes in chronic disease
• Resists lysosomal degradation

Question 5

Coxiella burnetii infection

Answer 5

• Acute 20d incubation, sudden onset of headache, chills, mild respir. symptoms, 50% have hepatosplenomegaly
• Chronic months to yrs incubation- subacute endocarditis, insidious w/ poor prognosis

Question 6

Ehrlichia chaffeensis

Answer 6

• Rickettsiaceae bacteria
• Causes human monocytic ehrlichiosis
• Lone star tick is primary reservoir
• Intracellular replication w/ ability to sequester or destroy infected circulating cells

Question 7

Ehrlichia chaffeensis infection

Answer 7

• Like those of Rocky Mountain spotted fever, ~12d after tick bite- a high fever, headache, malaise, myalgia, also a leucopenia causes by leukocyte destruction and thrombocytopenia are observed

Question 8

Rickettsial diseases such as RMSF, louse-borne, and scrub typhus therapeutic approaches

Answer 8

• Antibiotic therapy initiated early- first week of illness- highly effective
• Doxycycline

Question 9

Ehrlichia chaffeensis therapeutic approach

Answer 9

• Doxycycline

Question 10

Acute Q fever therapeutic approach

Answer 10

• Doxycycline

Question 11

Chronic Q fever therapeutic approach

Answer 11

• Combination of doxycycline w/ hydroxychloroquine
• Requires prolonged course of therapy

Question 12

Chlamydial infections therapeutic approach

Answer 12

• Doxycycline 100mg orally 2x a day for 7 days
• Azithromycin 1g orally in a single dose

*trying to shut-down bacterial protein synthesis w/ these drugs