Exotic Pulmonary Pathogens Flashcards
What are the Gram staining and cell characteristics of Bacillus anthracis?
Gram +, large non-motile rod with square ends (box car is the buzzword)
What are the virulence factors of Bacillus anthracis?
Capsule composed of D-glutamate (unique) and anthrax toxins –> also forms spores
How is Bacillus anthracis transmitted?
Cutaneous contact; can be aerosolized droplets that cause pneumonic disease
What are the 3 toxins produced by Bacillus anthracis?
Lethal factor –> cleaves host MAP kinases
Edema factor –> interferes with immune response
Protective antigen –> facilitates entry of lethal factor and edema factor into host cells
What are the clinical findings in Bacillus anthracis pneumonic disease (brucellosis or Malta fever)?
Onset 4-6 days
Sudden high fever, chills, profuse sweating, dyspnea, hypoxia, and tachycardia
What is seen on CXR with Bacillus anthracis?
Widened mediastinum with infiltrates and pleural effusions
How is Bacillus anthracis diagnosed?
1) CXR or CT
2) Can culture blood or sputum
3) Measure antibodies or toxins in blood
How do you treat Bacillus anthracis infection?
Ciprofloxacin for 60 days (dormant spores in macrophages) If severe, IV cipro + a penicillin or cephalosporin
What are the Gram staining and cell characteristics of Brucella spp.?
Small Gram negative coccobacillus –>intracellular bacterium (no capsule)
How is Brucella spp. infection usually contracted?
1) Contaminated dairy products
2) Direct contact with secretions of infected animals
What are the pathogenic mechanisms of Brucella spp.?
Live inside macrophages and illicit granuloma formation with giant cells –> endotoxin (LPS)
What are the clinical findings in Brucella spp.?
1) Fever, chills, fatigue, malaise, anorexia, weight loss
2) Enlarged lymph nodes, spleen, and liver
3) Pancytopenia
4) Large lung nodules on CXR
How is Brucella spp. diagnosed?
1) Culture in enriched media and 10% CO2 (not common)
2) Rise in antibody titer of at least 1:160 (best diagnostic)
How is Brucella spp. treated?
Tetracycline or doxycycline + rifampin
What are the Gram staining and cell characteristics of Burkholderia pseudomallei?
Gram negative rod; facultative intracellular bacterium
How is Burkholderia pseudomallei infection acquired?
Inhalation of aerosolized bacteria; typically after storms where bacteria in soil are aerosolized
What are the pathogenic mechanisms of Burkholderia pseudomallei infection?
1) Capsule
2) Can mediate host cell lysis to infect other cells
3) Can use actin network to propel itself into adjacent cells
4) Can remain dormant in host for years
What are the clinical findings of Burkholderia pseudomallei infection?
High fever, headache, anorexia, general muscle soreness, chest pain, cough
CXR shows small nodules and consolidation in upper lobes
What are the diagnostic tests for Burkholderia pseudomallei infection?
1) Culture from blood, urine, or sputum
2) Measuring specific antibodies
How is Burkholderia pseudomallei infection treated?
8 week course of ceftazidime –> 6 months if pt is immunosuppresed
What are the names of the disease caused by Burkholderia pseudomallei infection?
Meliodosis or Whoitmore’s disease
What is the name of the disease caused by Coxiella brunetii infection?
Q-fever
What are the Gram staining and cell characteristics of Coxiella brunetii?
Gram negative bacillus; obligate intracellular parasite
How is Coxiella brunetii infection spread?
1) Found in sheep, cattle, and goats; transmitted to humans that handle contaminated viscera or drink contaminated milk
2) Infected tick bite
3) Aerosolized spores (most serious form)
What is the pathogenic mechanism of Coxiella brunetii infection?
Obligate intracellular parasite –> evades humoral defenses
What are the clinical findings of Coxiella brunetii infection?
30-50% are asymptomatic Atypical pneumonia lasting 2-4 weeks –> sometimes has liver and heart involvement
What diagnostic tests are used for Coxiella brunetii?
Serological –> looking for high antibody titers to Q-fever antigen
How is Coxiella brunetii infection treated?
Most resolve spontaneously, but doxycycline can shorten duration
What are the Gram staining and cell characteristics of Francisella tularensis?
small pleomorphic Gram negative rod; obligate intracellular bacterium
What are the virulence factors of Francisella tularensis?
1) Atypical lipopolysaccharide that is not recognized by TLR-4
2) May produce capsule
How is Francisella tularensis transmitted?
1) Tick bite, or blood-to-blood contact with infected animal (think hunters in Arkansas)
2) Aerosolized droplets
3) Ingestion in food or water
What are the clinical findings of Francisella tularensis infection (tularemia)?
1) Sudden onset of flu-like symptoms
2) Regional lymph nodes become painful and swollen
3) CXR shows spotted infiltrates, lobar pneumonia, and pleural exudation
What diagnostic tests are used for Francisella tularensis infection?
1) Agglutination tests
2) Fluorescent antibody staining of infected tissue
How is Francisella tularensis infection treated?
Streptomycin
What are the characteristics of the hantavirus?
1) Enveloped
2) Segmented
3) Single-stranded (-) sense RNA virus
What is the epidemiology of hantavirus infection?
Mostly in young healthy adults that go camping and shit
What disease is caused by hantavirus infection?
Hantavirus pulmonary syndrome
How is hantavirus transmitted to humans?
Aerosolized rat excreta…
What are the clinical findings of hantavirus pulmonary syndrome?
Flu-like symptoms and myalgia of large muscle groups that rapidly progress to interstitial pulmonary edema and respiratory failure… silly little viruses
What are the CXR findings in hantavirus pulmonary syndrome?
1) Bilateral interstitial and alveolar infiltrates
2) Pleural effusion
3) Normal heart size
How is hantavirus pulmonary syndrome treated?
1) Early, aggressive intensive care
2) Assisted ventilation
3) Maintaining electrolyte balance
What are the Gram staining and cell characteristics of Yersinia pestis?
Small Gram negative encapsulated rod
What are the unique staining characteristics of Yersinia pestis?
Bipolar staining –> resembles a safety pin (Step 1 buzzword)
What disease is caused by Yersinia pestis infection?
THE PLAGUE or black death
How is Yersinia pestis transmitted to humans?
Bitten by flea that has bitten infected rodent
Can also transmit from another person through aerosolized droplets (most fatal form)
What is seen on CXR with Yersinia pestis infection?
Effects lower lung zones with bilateral pleural effusions
What are the pathogenic mechanisms of Yersinia pestis?
Spreads regional lymph nodes –> very swollen and tender (called buboes) and can disseminate
What are the virulence factors of Yersinia pestis?
1) Caps
2) Endotoxin (LPS)
3) V & W antigens allow intra-macrophage survival
4) Yersinia outer proteins injected by Type III secretion system prevent phagocytosis and cytokine production
5) Exotoxin
What are the clinical findings of Yersinia pestis infection?
High fever, myalgia, extreme fatigue/collapse
Septic shock and pneumonia
What diagnostic tests are used for Yersinia pestis?
1) Culture of blood or pus
2) Giemsa or Wayson stain –> safety pin appearance
3) Fluorescent antibody staining
How is Yersinia pestis infection treated?
Streptomycin and tetracycline
