Bacterial Infections with Animal Reservoirs or Insect Vectors

Question 1

Brucellosis

Answer 1

• small aerobic G- rods
• infect monocytes and macrophages
• chronic febrile disease acquired from domestic animals
• B. melitensis - sheep and goats
• B. abortus - cattle
• B. suis - swine
• B. canis - dogs
• multiply in macrophages
• can cause granulomas on organs
• undulent fever

Question 2

Yersinia pestis

Answer 2

• G- rod
• found in wild rodents and transmitted by fleas
• replicate in macrophages, carried to regional lymph and produce hemorrhagic necrosis

Question 3

Bubonic plague

Answer 3

• Y. pestis
• HA, fever, malaise and enlargement of LN
• progresses to septic shock within hrs to days

Question 4

Septicemic plague

Answer 4

• Y. pestis
• bacteria inoculated directly into the blood (no buboes)
• death within 48 hrs

Question 5

Pneumonic plague

Answer 5

• Y. pestis
• inhalation
• Respiratory insufficiency, endotoxic shock, and death within 1-2 days

Question 6

Tularemia

Answer 6

• Francisella tularensis
• G- coccobacillus
• reservoirs in rabbits and rodents
• multiplies at site of inoculation, producing focal ulcer there and spreads to regional LN
• survives within macrophages
• lesions are initially exudative then undergo central necrosis
• ulercoglandular, oculoglandular, typhoidal, pneumonic

Question 7

Anthrax

Answer 7

• B. anthracis, spore-forming G+ rod
• necrotizing disease via toxin
• reservoir in goat, sheep, cattle, horses, pigs, and dogs
• malignant pustule, pulmonary, septicemic, or GI

Question 8

Listeriosis

Answer 8

• Listeria monocytogenes
• motile G+ coccobacillus
• Systemic multiorgan infection
• evades intracellular and extracellular host defense by lysosomal pH activation of an exotoxin that then disrupts membrane and allows bacteria to enter cytoplasm and hijack cell
• can spread cell to cell without ever seeing extracellular environment
• meningitis is most common form of disease in adults
• immunocompromised –> septicemic, shock, DIC

Question 9

Cat Scratch Disease

Answer 9

• Bartonella henselae, small G- rods
• suppurative and granulomatous lymphadenitis
• Parinaud oculoglandular syndrome

Question 10

Glanders

Answer 10

• Pseudomonas mallei, small G- bacillus
• infection of equine, rarely transmitted to horses
• granulomatous disease
• acute –> almost always fatal
• chronic –> mimics TB, mortality 50%

Question 11

Bartonellosis

Answer 11

• Bartonella bacilliformis, small multiflagellated G- coccobacillus
• causes acute anemia and chronic skin disease
• first, acute hemolytic anemia (Oroya fever) followed by chronic dermal phase (verruga peruana)