Uncommon Bacterial Pathogens Flashcards
Bacillus Antracis –
Bacteriology
- what is the distinctive morphology?
- Where does it live? How is it transmitted ?
Gram positive rods – large “boxcars”
forms spores in the laboratory and in the field
Non motile; facultative anaerobic
Lives in the soil and in herbivores
Transmitted by coming into contact with spores or contaminated meat
-NOT TRANSMITTED PERSON TO PERSON
Describe the pathogenesis and virulence factors of Anthrax:
Two Plasmids:
1) Encodes Poly D Glutamic Acid Capsule– (unique bc its not an amino acid capsule, not a polysaccharide)
2) Tripartite Toxin Plasmid:
- Protective Antigen
- Edema Factor
- Lethal Factor
Describe the mechanism of Edema Factor and Lethal Factor?
what organism produces these?
Bacillus Antrhacis
- Edema factor (A subunit) – Adenylate Cyclase; raises cAMP; intereferes with phagocytosis and signaling of phagocytes
Lethal Factor (A subunit): metalloproteases; MAP kinase Kinase which paralyzes lymphocytes leading to death
What are the three disease types than can manifest from anthracis?
Briefly Describe the presentation of each
Cutaneous
Gastrointestinal –
Inhalation
Describe the cutaneous form of anthrax –
- presentation
- what is the mortality rate?
Cutaneous – Most common (95%)
Spores enter through breaks in the skin.
Presents as painless pruiritic pustule that quickly enlarges leave BLACK ESCHAR + EDEMA
No Fever or LAD
20% mortality rate
Describe GI anthrax:
How do you get it?
Presentation?
mortality rate
Gastro-intestinal:
spores ingested (eg from contaminated beef).
Can survive high temperatures, so cooking it doesn’t kill it.
Symp - fever, gastroenteritis, vomiting, hematemesis, bloody diarrhea… Toxemia –> Death
Symptoms are non specific
higher mortality rate (50+%) bc its hard to recognize
Describe Inhalation anthrax
- How do you get it?
- Initial presentation?
- terminal presentation?
- what is distinct about the CXR?
- Spores are inhaled
- gereminate in the lung macrophages
Symptoms (2-5 days) fever, malaise, cough, myalgia
CXR: Widened mediastinum (hemorrhagic adenitis of the hilum)
Late symptoms (1-2 days): hemorrhagic pleural effusions, hypoxia, cyanosis, dyspnea, shock and death
Treatment of Anthrax:
Prevention of Anthrax
Traditional : PCN + Doxycyclin
Animal studies: Cipro
2001 Survivors: FQ + clinda OR Rifampin
Vaccine: noncapsulated strain that has protective antigen but not the other toxins
Yersinia Pestis
- Bacteriology
- how are humans infected ?
- what is the reservoir in the environement
GN coccobaccilus
Humans infected from flea bite
Reservoirs: rats, squierrels, rabbits
Virlence factors of Yersina Pestis
- 2 plasmids which encode:
type 3 secertions
Fibrinolysis
(if no fibrinolysis, cannot become invasive; stays as local infection)
Disease forms of Yersinia Pestis?
- how does each present ?
Bubonic Plague:
Bubo = large infected LN
Sx: Bubo, HA, malaise, myalgia
Pap/Purpuric lesion at the site of the flea bite
Pneumonic Plague: Highly contagious;
HA, mailse, fever, cough, dyspnea, cyanosis, hemoptysis, respiratory failure
Septicemia: No Obvious Bubo or PNA; patient’s present with sepsis. Die from shock and DIC
Medical management of Yersinia
FQs (cipro)
Tetracycline
TMP/SMX
Genitmicin/streptomycin
Prophylaxis:
- bubonic contacts: TMP/SMX, tetracyclines,
Pneumonic contacts: cipro, tetracyclines
• Francisella tularensis - Epidemiology: what part of the world is it found? what animals harbor it? What is the ID? how is it transmitted?
- Found in the norther hemisphere
- Rabbits (Skinning)
and ticks
Very low ID: 1-10 CFU
no person to person trasmission
What are the important clinical forms of • Francisella tularensis
Ulceroglandular: ulcer with regional adenopathy at site of tick bite
Pneumonic: similar to pneumonic plague presentation
Abrupt onset fever, chills, HA, myalgia, non productive cough,
CXR: segmental, lobar infiltrates, hilar adenopathy
Treatment of • Francisella tularensis
is there a vaccine?
Tetracyclines or FQ
(Strepto and gentimicin in the past)
No Vaccine
