Bacillus Flashcards
What kind of Bacteria are Bacillus spp.?
Large Gram + rods, Endospore forming
Rapidly growing, aerobic or facultative anaerobes
Ubiquitous in nature
Most are soil saprophytes
What kind of pathogen is Bacillus Anthracis?
An obligate mammalian pathogen
What is the source of infection for herbivores in Bacillus anthracis infection?
Soil contaminated with spores
What are the two main virulence factors of B. anthracis?
- Capsule
- Anthrax toxin
Both encoded by plasmids
How is the B. anthracis capsule produced?
Only in vivo
What are some characteristics of the B. anthracis capsule?
Polymers of D-glutamic acid
Encoded on plasmid
Anti-phagocytic
Stain pink
What is a diagnostic feature of B. anthracis?
McFadyean reaction on staining with polychromatic methylene blue
What are three factors of Anthrax toxin?
- Edema factor
- Lethal factor
- Protective factor
Together these cause increased vascular permeability and cell necrosis
What is the pathogenesis of B. antracis?
Spore Ingestion/exposure
Endospores germinate
Intracellular survival allow growth initiation
Capsule and edema factor inhibit phagocytosis
Vegetative cells grow rapidly
Complete anthrax toxin causes cell death and affects vascular permeability
What are some predisposing factors that increase B. anthracis exposure?
History
Flooding
Soil conditions
Warm temperature
Drought conditions
Who are the most susceptible to B. anthracis?
Least susceptible?
Cattle most susceptible
Pigs least susceptible
How will most cattle with B. anthracis be found?
Found dead with unclothed blood and dark bloody fluid exuding form body cavities
What is septicemia anthrax?
Death in 1-5 days, with massive spleen, extensive hemorrhages, bloody urine, blood from large bowel
What is local anthrax?
Less susceptible species; severe edema at entry site, malignant carbuncle in skin (woolsorter’s disease of people)
What can a biological warfare agent exposure lead to?
Multiple manifestations
What are 6 common forms of anthrax?
- Per acute septicemia=ruminants
- Acute septicemia=horses
- Pulmonary=man (wool sorters)
- Pharyngeal=pigs, dogs
- Intestinal=man, pigs, horse
- Cutaneous=man (malignant carbuncle)
What are some antemortem signs of per acute/acute septicemia of anthrax?
Rapidly fatal, high fever, bleeding from orifices, shock, respiratory distress
What are some postmortem signs of per acute/acute septicemia of anthrax?
Dark, unclothed blood, incomplete rigor mortis, Splenomegaly
Is Bacillus anthracis reportable? Why?
Yes, spores persist for decades in ground
What should you do if you suspect anthrax as a differential DX:
DO NOT conduct field necropsy; call state/federal officials
How would you DX anthrax?
McFadyean’s methylene blue; blue staining of organisms with a pink capsule
PCR
Aerobic culture of blood
What BSL is anthrax?
BSL-3
List the 3 ways anthrax is a zoonosis
- Cutaneous=woolsorter’s disease (malignant carbuncle)
- Aerogenous=pulmonary anthrax (bioterrorism)
- Oral=intestinal and oropharyngeal anthrax
Where should antimicrobial susceptibility testing for anthrax be done?
Approved referenced labs
What drugs would be used to TX anthrax?
Penicillin, tetracycline, docycycline, ciprofloxacin
How could anthrax be controlled?
Vaccinate healthy animals in endemic/high risk areas only
