Block 3 Flashcards
Bacillus overview
describe basic features
Gram pos., aerobes or facultative anaerobes, catalase pos., oxidase
neg., most are non-pathogenic,** REPORTABLE, zoonotic**
Bacillus overview
what do they look like?
Large rectangle/square rods in chains, motile (except B. anthracis),
Medusa head colonies under microscope
Bacillus overview
where are they found? why do they survive there?
what result?
Endospore forming and they survive very well in soil (soil
saprophytes)
* Endospores allow the bacteria to have an extremely durable dormant
state
* They are the most durable type of cell found in nature
* Resistant to extreme adverse conditions, and stay viable for long periods
of time
Bacillus overview
what is the most important pathogen? why?
B. anthracis is the most important pathogen as it is an obligate
mammalian pathogen
**anthrax=sudden death
Bacillus anthracis
where?
Africa, india, china
Bacillus anthracis
source?
waht result with O2 exposure?
Source of infection is usually soil that has been contaminated by bacterial spores
* O2 exposure will increase the process of sporulation by the bacteria
Bacillus anthracis
Susceptibility by species from most to least:
what is most resistent and why?
Susceptibility by species from most to least: cattle, sheep, horses, goats, dogs, pigs
* Birds are almost completely resistant to anthrax because of their higher body temp.
Bacillus anthracis
Factors that predispose an animal to anthrax infection:
name 4
- History of previous anthrax deaths and/or buried carcasses
- Alkaline soil that is rich in Ca and N and has a high moisture content
- Warm temps and repeated flooding/drying
- Dry/drought conditions that force animals to graze closer to the soil
Bacillus anthracis
Virulence factors: what is needed?
both the capsule and tripartite anthrax toxins are needed for full virulence
Bacillus anthracis
- Virulence factors:
what is capsule?
- Capsule: polymers of D-glutamic acid will inhibit phagocytosis, only produced in vivo (AKA we will not see a capsule when growing B. anthracis in
the lab)
Bacillus anthracis
- Virulence factors:
Tripartate anthrax toxin:
name and explain
1) Protective antigen (PA): cell binding factor to aid in translocation into host cell (acts like a channel)
2) Edema factor (EF): calmodulin-dependent adenylate cyclase, enter the cell after PA is formed and increases the amount of cyclic AMP, this disrupts water
homeostasis and results in edema, neutrophils are the primary target
3)** Lethal factor** (LF): zinc metalloprotease, also enters via PA, causes cell death and tissue necrosis/hemorrhage
Bacillus anthracis
- Transmission:
- IP:
- Transmission: ingestion (main), inhalation, cutaneous
- IP: hours to days
Bacillus anthracis
- CS vary by species
- Ruminants:
what is it?
what does it look like?
what result?
- Ruminants: peracute septicemia (blood disease)
- Rapidly fatal disease due to respiratory distress and shock
* Can see bleeding from orifices - Post-mortem: blood is dark and unclotted, incomplete rigor mortis (because of increase in cyclic AMP), splenomegaly
Bacillus anthracis
- CS vary by species
- Horses:
- Horses: acute septicemia
Bacillus anthracis
- CS vary by species
- Pigs & dogs:
- Pigs & dogs: pharyngeal (swelling of the throat area)
Bacillus anthracis
- Pigs & dogs & humans:
- Pigs & dogs & humans: intestinal
- Humans by ingestion of an infected animal
Bacillus anthracis
- CS vary by species
- Humans (Wool sorters disease):
- Humans (Wool sorters disease): pulmonary
- Inhalation of spores and can take 2 months to manifest, rare but very deadly
- Bioterrorism attacks in the US when turning spores into powder form
- Q. is this contagious from human to human? NO
**not in lungs - Humans (malignant carbuncle): cutaneous
- Most common but least dangerous, caused by sores getting into wounds, localized necrotic skin
Bacillus anthracis
is it zoonotic?
is it contagious?
yes
no
Bacillus anthracis
- Dx and sampling:
-
Do NOT do a field necropsy if anthrax is a possible cause of death- call the state and federal officials
* Obligate REPORTABLE BSL-3 agent and select agent (potential use as bioterrorism agent) - Direct exam of samples:
- Collect blood from tail vein
- Look for blue stained bacteria with a pink capsule (McFadyean’s methylene blue)- blood or organ smears
- Large rectangle/square rods in chains that are encapsulated (gram stain)
- Aerobic culture on blood agar or PCR
Bacillus anthracis
- Tx will vary for endemic versus non-endemic regions
endemic?
non-endemic?
- Endemic: annual vaccine, long-acting penicillin for valuable livestock (this is very costly) no $
- Non-endemic: quarantine affected herd, use PPE when handling infected animals and material, long acting antimicrobials,
observe animals for 2 weeks that have been in contact with infected, vaccinate after AB treatment, incinerate carcasses or
deep burial of at least 6.5 ft under a layer of quicklime (anhydrous Ca oxide), disinfect all contaminated materials
Bacillus anthracis
Tx
Q. Why can’t we burn carcasses in the field?
b/c endospores don’t die
Acid fast partial bacteria
3 kids what are they?
Corynebacterium
* Rhodococcus
* Nocardia
Corynebacterium overview
describe
Gram pos., pleomorphic, aerobes or facultative aerobes, non-spore forming, short mycolic
acids in cell wall (hence ACID FAST PARTIAL)
Corynebacterium overview
where?
is it host specific?
where found?
result?
Commensals on the mucous membranes (usually host specific) and can also be found in the
environment (soil)
* Opportunistic bacteria causing pyogenic/pus type infections (infection usually follows a trauma)
Corynebacterium overview
- Virulence factors:
name 3 and what result
- External lipid coat (mycolic acids): protects bacteria from enzymes in the host phagocytic cells
- Exotoxin Phospholipase D (PLD): causes damage to the endothelial cells which allows for increased
vascular permeability - Diptheria toxin: interferes with protein synthesis by inhibiting RNA translation
Corynebacterium overview
- Virulence factors:
what is causes damage to the endothelial cells which allows for increased
vascular permeability
Exotoxin Phospholipase D (PLD):
Corynebacterium overview
- Virulence factors:
what is protects bacteria from enzymes in the host phagocytic cells
- External lipid coat (mycolic acids):
Corynebacterium overview
- Virulence factors:
what is interferes with protein synthesis by inhibiting RNA translation
- Diptheria toxin:
Corynebacterium overview
animal has a skin injury that is exposed to purulent material, bacteria enter
and migrate to the LN’s, replicates within phagocytes (facultative intracellular pathogen), and
the result is the formation of abscesses
what is this called?
what is the most common way for bacteria to spread?
Pathogenesis:
- Purulent abscesses is the most common way the bacteria is spread