Lecture 12 & 13 Flashcards
What is the biocontainment level for Erysipelothrix?
2
Does Erysipelothrix form spores?
NO
Is Erysipelothrix gram positive or negative?
positive
Describe the appearance of Erysipelothrix
Slender, non-branching rods or chains of rods
Irregular morphology (curved)
Describe the metabolism of Erysipelothrix (3)
Facultative anaerobic
gamma hemolytic or weekly alpha hemolytic on blood agar
Catalase negative
Where is Erysipelothrix found?
Wide range of spp - mammals, birds, reptiles, fish, shellfish, crustaceans & wild ungulates
Shed in faces of pigs
Persists in envr
What are the virulence factors of Erysipelothrix? (3)
Capsule - provides resistance to phagocytosis & allows organism to survive in the oxidative burst within macrophages
Neuraminidase - promotes attachment & aids in invasion of mucosal surfaces & vasculature
SpaA PRO - surface PRO that aids in attachment
What virulence factor of Erysipelothrix is responsible for generating cell-mediated immunity rather than humoral? Is this protective?
SpA PRO
Yes, antibodies are protective
What disease does Erysipelothrix rhusiopathiae cause in pigs?
Swine Erysipelas
What is the pathogenesis of Swine Erysipelas caused by Erysipelothrix rhusiopathiae?
Affects pigs older than 3 mo due to waning material immunity
Fecal-oral exposure
Enters body through palatine tonsils followed by systemic spread (bacteremia)
In acute case, it can lead to DIC & thrombi. Thrombi get lodged in capillaries & venues –> ischemic necrosis & lesions
What are the symptoms of Acute Swine Erysipelas caused by Erysipelothrix rhusiopathiae? (6)
Sudden onset
Pyrexia & sometimes death
Depression
Inappetence
Diamond skin lesions 2-3 days after exposure (if severe, the diamond lesions won’t occur before death)
What are the symptoms of Subacute Swine Erysipelas caused by Erysipelothrix rhusiopathiae?
Disease is less severe than acute
What are the symptoms of Chronic Swine Erysipelas caused by Erysipelothrix rhusiopathiae? (3)
Long term sequelae following acute disease
Arthritis & stiffness - thrombi can become lodged in joints
Poss cardiac insufficiency if damage to heart valves during acute phase
What are the symptoms of Erysipelothrix rhusiopathiae in turkeys? (4)
Begins with death of several birds & others which are droopy
Toms may have congested, purple snoods
Death is per-acute
Endocarditis is usually the cause in turkeys that died
Describe the pattern of disease of Erysipelothrix rhusiopathiae in wild ungulates
Large die-offs
Mortality due to this organism is new
Poss effecting naive pop
Is Erysipelothrix rhusiopathiae zoonotic?
To those with exposure risk - vets, butchers & fish handlers
Presents as skin lesions & can lead to L sided endocarditis
What disease does Erysipelothrix tonsillarum cause in dogs?
Endocarditis
What are the symptoms of Erysipelothrix tonsillarum in dogs? (2)
Fever
Recent onset of murmur
How do you tx Erysipelothrix tonsillarum in dogs?
Penicillin
Extended tx length required
What disease does Erysipelothrix spp cause in ornamental fish?
Death
What are the clinical signs of Erysipelothrix in ornamental fish?
Lethargy
Hovering in the water
Hemorrhage of fins & skin
What do samples do you collect for Erysipelothrix?
Necropsy - liver, spleen, kidney, heart, synovial tissue, long bone samples
Blood cultures
Difficult to collect skin samples
How do you handle samples for Erysipelothrix spp?
DO NOT FREEZE
How does the lab test for Erysipelothrix?
Blood agar
Selective media - including agar containing a/bs
MALDI-TOF
How do you tx for Erysipelothrix spp?
Penicillin
Pathology may complicate
What tx do you avoid for Erysipelothrix? (3)
Sulfonamides
Aminoglycosides
GLycopeptides (vancomycin)
What is the containment level for B. anthracis?
3
What is the biocontainment level for B. cereus?
2
What is the biocontainment level for B. subtitles?
1
Describe the appearance of Bacillus (4)
Large
Spore forming
Gram positive
Rods
Describe the metabolism of Bacillus
Facultative anaerobe
Describe the appearance of Bacillus on a plate (2)
Large, irregular colonies
Describe the appearance of Bacillus anthracis on a plate (2)
grey
Non-hemolytic colonies
What spp have the Medusa heads on a gram stain?
Bacillus anthracis
Where is Bacillus found?
Envr - water & soil
Spores survive for decades - highly resistant
What are the virulence factors for Bacillus anthracis? (3)
Protective antigen- forms heptameric pores in cell walls (within host cells)
THEN, an edema factor or lethal factor will bind to create toxins
Lethal toxin - affects macrophages inhibiting macromolecular syn & stimulates apoptosis
Edema toxin - results in increase cAMP levels intracell & effects H2O homeostasis
(FYI- these 3 PROs are inactive on their own, need to come together to be activated)
Describe the virulence process of Bacillus anthracis
Capsule forms around the vegetative cells & other factors for a PRO
Protective antigen binds to host cells
They aggregate together to form a heptamer
Edema or lethal factor bind to the heptamer resulting in endocytosis of the entire complex
Complex spans the entire cell membrane allowing both factors to be cleaved & enter the cytoplasm of the cell to exert their toxic effects
What is the virulence factor for Bacillus cereus ?
Exotoxins responsible for gastroenteritis
What is the virulence factor for Bacillus thuringiensis?
Crystal toxins - digestion of crystal liberates Cry toxin & disrupts the gut
Used as larvicide in mosquito control
What is the virulence factor for Bacillus subtilis?
Non-pathogenic
Describe the process of the motility test
Put swab in the media straight down the middle (use needle or straight wire)
If it diffuses outwards from the stab line then it is positive & if it only stays in the stab line then it is negative
Diff spp have diff susceptibility to Bacillus anthracis, why might that be? What spp have the most, intermediate & lowest susceptibility to disease?
Due to the envr that the spp resides
If they are in an envr with high exposure to soil then they have more exposure to spores then they are very suscpetible - includes cattle, sheep & goats (most susceptible)
For those spp with moderate exposure to soil & spores they have intermediate susceptibility - horses & humans
For spp which only are exposed to soil when scavenging they have the lowest susceptibility - pigs, birds & carnivores
How do ruminants acquire Bacillus anthracis?
Ingestion of an endospore
Often seen when there is a drought followed by heavy rainfall
What is the outcome if a ruminant is exposed to Bacillus anthracis?
Sudden death
Peracute disease
What are some signs during a necropsy that the animal has been infected by Bacillus anthracis?
Failure to clot
Incomplete rigor mortis
Splenomegaly - if you cut into a carcass & blood flows freely
Why should you never perform a necropsy if you suspect Bacillus anthracis?
B/c if the organisms are exposed to O2 they sporulate & since they are extremely resistant spores it will be very difficult to rid them of the envr
If you see splenomegaly, STOP cutting
Call CFIA if you suspect
How does Bacillus anthracis present in horses?
Acute intestinal disease - colic, diarrhea, fever & depression
Localized lesions can be seen
May see dependent edema = thorax, abdomen, prepuce, mammary gland
Followed by fatal septicaemia
How do horses become exposed to Bacillus anthracis?
Thought to be due to insect transmission
What are the 4 forms of Bacillus anthracis in humans?
Cutaneous - most common
Pulmonary - inhale spores
Oropharyngeal - ingest spores
Gastrointestinal - ingest spores
How do you collect a sample for Bacillus anthracis?
Call CFIA
Do not perform necropsy
Collect blood from ear
If you are working in a dusty envr, use protection
How do you handle Bacillus anthracis samples?
DO NOT FREEZE
How does the lab diagnose Bacillus anthracis?
Direct microscopy - look for encapsulated organisms from tissues
How does the lab dx non-anthracis bacillus spp?
Culture
How do you get rid of Bacillus anthracis from the envr? (3)
Very difficult to get rid of
Remove top 20cm of soil
Disinfect soil & equipment with formalin
Burn or bury contaminated disposables along with carcasses
How do you tx Bacillus anthracis? (6)
High dose of penicillins or tetracyclines
Vacc is available
Antimicrobial prophylaxis may be appropriate in some outbreak situations
Control area - keep animals out
Proper disposal of carcasses
Prevent additional contamination of the envr
