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Bacteriology > Bacillus > Flashcards

Bacillus Flashcards

1
Q

Microbial characteristics of bacillus

A

-varying biocontainment levels
-large, spore forming gram positive rods
-aerobic, or facultative anaerobic
-form large, irregular colonies

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2
Q

Biocontainment of B. anthracis

A

Level 3

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3
Q

Biocontainment of B. cereus

A

level 2

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4
Q

Biocontainment of B. subtilis

A

level 1

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5
Q

Host of bacillus

A

-Ubiquitous, found in environment (water, soil)

-spores survive for decades (highly resistant to desiccation, heat, radiation, disinfectants)

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6
Q

B. anthracis appearance on stain

A

appears like a medusa head on gram stain

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7
Q

Bacillus taxonomy

A

B. anthracis= non hemolytic, susceptible to penicillin

B. cereus and B. thuringlensis= motility

B. mycoides= no motility

**ID to species level with MALDI-TOF

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8
Q

Virulence factors for bacillus

A

-encapsulated (genes for this found on pXO2 plasmid)
-Need all 3 of these to function:
>protective antigen
>edema toxin
>lethal toxin

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9
Q

Protective antigen

A

-forms heptameric pores in cell wall allowing for edema factor and lethal factor to enter

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10
Q

Lethal factor

A

-inactivates MAPK kinases, disrupts cell signalling ultimately leading to apoptosis

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11
Q

Edema factor

A

calmodulin dependent adenylate cyclase, increased intracellular cAMP leads to edema

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12
Q

B. cereus virulence factors

A

produce exotoxins responsible for gastroenteritis

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13
Q

B. thuringiensis virulence factors

A

*insect pathogen
-produce crystals toxins which disrupt the insect gut when ingested

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14
Q

B. subtilis virulence

A

largely non pathogenic

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15
Q

B. anthracis in cattle and sheep

A

-acquired by ingesting endospores; often seen after a drought and heavy rainfall
-can just find peracute disease= sepsis= sudden death
OTHERWISE see depression, edema, skin lesions

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16
Q

Signs of sudden death from B. anthracis

A

-incomplete rigor mortis
-splenomegaly
-failure to clot (if you cut, stop!!). On exposure to oxygen, sporulation occurs and are extremely resistant to disinfection

17
Q

B. anthracis in horses

A

-presents as acute intestinal disease (colic, diarrhea, fever, depression). Can also see localized lesions most likely due to insect transmission
-can see edema in thorax, abdomen, prepuce, mammary gland
-All followed by fatal septicemia

18
Q

B. anthracis in pigs

A

-can see oral/pharyngeal ulcers/lesions along site of entry, regional lymphadenitis, and ulcerative and haemorrhagic enteritis

**carnivores are rarely affected but when diseased, septicemia with massive exposure occurs

19
Q

Wildlife outbreaks in hippos with B. anthracis

A

-Animal die offs of hippos
-serious health concern because large animals increase exposure, or consumption of carcasses associated with human disease

20
Q

B. anthracis in humans

A

-can be cutaneous or systemic

21
Q

B. cereus in humans

A

-causes gastroenteritis

22
Q

B. licheniformis in cattle and sheep

A

-causes abortion and mastitis

23
Q

B. subtilis in cattle and sheep

A

-causes abortion and mastitis

24
Q

Paenibacillus larvae in honeybees

A

-acts by multiplicity of mechanisms (chitin degrading enzymes, toxins causing intestinal epithelial cell death, S-layer proteins on cell surface, protect from insect immune system)
-causes american foulbrood disease

**infection control is key. Antibiotic and probiotics for prevention

25
Q

Susceptibility of animals to bacillus anthracis

A

Most susceptible: cattle, sheep, goats

Intermediate: horses, humans

Lowest: pigs, birds, carnivores

**some species are more resistant because they eat dead animals/diet/lifestyle

26
Q

Distinct forms of B. anthracis

A
  1. Cutaneous
  2. Pulmonary
  3. Oropharyngeal
  4. Gastrointestinal
27
Q

Cutaneous form of anthrax

A

-direct contact with infected animal tissues
-lesions within 2-5 days post exposure, mortality rate=10-20% if untreated

28
Q

Pulmonary form of anthrax

A

-inhalation of endospores, phagocytosis in lungs
-lethal toxin kills macrophages
-hemorrhagic necrosis of mediastinum
-1-3 days incubation, mortality rate 80-90% if untreated

29
Q

Oropharyngeal form of anthrax

A

-associated with ingestion of spores or vegetative cells

-involves cervical and oral pain and edema. If untreated, sepsis occurs if untreated

30
Q

Gastrointestinal form of anthrax

A

-associated with ingestion of spores or vegetative cells

-results in fever, nausea, bloody vomit, sepsis (if untreated)

31
Q

Acute, self limiting gastroenteritis

A
  1. Emetic form= ingestion of cereulide toxin
    -1-6 hrs following ingestion
    -associated with rice, cream, milk products, pasta and infant formula
  2. Long incubation food poisoning =ingestion og hemolysins
    -watery diarrhea, nausea, tenesmus
    -associated with meat, vegetables, cakes sauces and dairy
    **some strains grow at temps 4-7degrees
32
Q

Sample collection of bacillus

A
  1. B. anthracis
    -no necropsy
    -can collect blood from ear
    -respiratory protection needed
  2. non-anthracis spp
    -use standard precautions
    -milk
    -tissues from aborted fetuses
33
Q

Sample handling for bacillus

A

-Do not freeze

34
Q

Lab ID

A
  1. B. anthracis
    -need biosafety cabinet
    -direct microscope (look for encapsulated organisms)
    -culture on blood agar (non hemolytic colonies)
  2. non-anthracis spp
    -culture!
  3. Blood from ear tip
    -use microscope and methylene blue staining
35
Q

Zoonoses of bacillus

A

B. anthracis
-difficult to remove; need to remove top 20cm of soil
-disinfect soil and equipment with formalin
-burn or bury contaminated disposables

PPE is critical

36
Q

Rare cases with B. anthracis

A

Outbreak: common things occur, but with large number of cases, you can see something unusual
-anthracis causing mastitis in cow

37
Q

Treatment of bacillus

A
  1. B. anthracis= penicillins or tetracyclines
    Avoid 2nd and 3rd generation cephalosporins and trimethoprim +sulfamethoxazole

**Avoid penicillins for B. thuringiensis

38
Q

Control measure for B. anthracis

A

-vaccination
-antimicrobial prophylaxis may be appropriate in some outbreak situations
-control the area (keep animal scavengers out)
-proper disposal of carcasses
-preventing additional contamination of environment

Bacteriology (16 decks)

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