Uncommon Bacterial Pathogens Flashcards
What 3 pathogens are on the “A” list of biological weapons?
Bacillus anthracis (Anthrax) Yersinia pestis (Plague) Francisella tularensis (Tularemia)
What is the morphology of Bacillus anthracis
Gram positive, spore forming rod
How is Bacillus anthracis transmitted?
Herbivores
Humans get it from contact with or ingestion of contaminated animal products
NO person to person transmission of inhalational anthrax
What are the virulence factors of Bacillus anthracis?
Poly-D-glutamic acid capsule
Tripartite toxin
What are the three proteins of the anthrax tripartite toxin?
Protective antigen (PA) Lethal factor (LF) Edema factor (EF)
What are clinical cutaneous features of anthrax?
Painless ulcer with black eschar and surrounding edema
What are clinical gastrointestinal features of anthrax?
Lesions in oropharynx and GI tract like the cutaneous form (echars)
‘thumb print” in haustra due to edema of bowel
What are clinical inhalational features of anthrax?
Inhale spores, taken up by macrophages to mediastinum
Early symptoms: widened mediastinum, pleural effusions
Terminal symptoms: fever, hemorrhagic mediastinitis, bacteremia, sepsis
What is the treatment for anthrax?
Fluoroquinolone + clindamycin or rifampin
What is the morphology of Yersinia pestis?
Gram negative bacilli
How is Yersinia pestis transmitted?
Natural hosts are rodents
Transmitted by rodent flea
What are the virulence factors of Yersinia pestis?
Type III secretion system
Fibrinolysin (allows spread through soft tissues and systemic disease instead of just cutaneous)
What are the 3 clinical forms of Yersinia pestis and their presentation?
Bubonic - large swollen lymph node (bubo), sudden onset headache, malaise, myalgia, fever
Pneumonic - aerosol and person to person transmission! pneumonia progresses rapidly to respiratory failure
Septicemic - end result of bubonic or pneumonic, death if untreated
What is treatment of Yersinia pestis?
Gentamicin or fluoroquinolones
How is Tularemia transmitted?
Rabbits/hares in winter, ticks in summer
NO person to person transmission
What are major clinical presentations of Tularemia?
Ulceroglandular - ulcer with regional adenopathy
Pneumonic - inhalation or secondary to bacteremia
What is treatment of Tularemia?
Gentamicin or fluoroquinolones
What is the morphology of Tularemia?
Gram negative coccobacillus
What is the morphology of Listeria monocytogenes?
Motile Gram positive rod
- Shows mushroom cloud in soft agar
Facultative anerobe, Beta hemolytic
What is the pathogenesis of Listeria monocytogenes?
Uses internalin to invade cells
Escapes phagosome using lysteriolysin
Usurps actin (ActA nucleates on one pole, propels through cytoplasm)
Protrudes through cell membrane, engulfed by neighboring cell
What is key to clearing a Listeria infection?
Cell mediated immunity (T cells)
What groups of people are most susceptible to Listeria infection?
Immunocompromised individuals
Pregnant women and neonates
What is the most common clinical manifestation in non-pregnancy associated Listeria?
Meningitis!!!
Leading cause of meningitis in immunocompromised hosts
What is the treatment for Listeria?
Penicillin, ampicillin
CEPHALOSPORINS are INEFFECTIVE
How is Bartonella transmitted?
Primarily by cats, fleas
What diseases does Bartonella cause and what are the clinical features?
Cat Scratch disease
- Unilateral adenopathy
Bacillary angiomatosis
- Neovascular proliferation of skin seen in HIV patients
What is the clinical presentation of Brucella?
Prolonged febrile illness
