Bacillus Flashcards by Jose Guillo

The only important pathogenic species of Bacillus in domestic animals

Bacilllus anthracis

How well did you know this?

Not at all

Perfectly

Principal Characteristics of Bacillus

large, Gram-positive, rods

How well did you know this?

Not at all

Perfectly

Oxygen requirement of Bacillus

Aerobic, some are facultative anaerobic

How well did you know this?

Not at all

Perfectly

Reproduction, fermentation, motility and enzyme test of Bacillus

Sporeforming

Most are catalase-positive, fermentative and non motile

How well did you know this?

Not at all

Perfectly

Public Health Significance of Bacillus

Humans are infected through contact with infected animals, hide, hair, wool, excreta, and soil, and ingestion of spores from milk and meat,

Occupational disease

How well did you know this?

Not at all

Perfectly

True or False: The spore of bacillus does not distend the sporangium and is smaller than the vegetative cell?

True

How well did you know this?

Not at all

Perfectly

In what temperature can the spores of bacillus be visualized?

42 C
or
37 C at longer hours

How well did you know this?

Not at all

Perfectly

Habitat and Ecology of Bacillus

Occur widely in nature: soil, water, air

Most common laboratory contaminants

Infected animals and animal product are reservoir

How well did you know this?

Not at all

Perfectly

Habitat and Ecology of Bacillus anthracis

Associated with alkaline or calcareous soil, in which the spores can survive for many years.

Survival in soil is favored by a neutral or alkaline pH, an ambient temperature of 20 C to 37 C, and a relative humidity of 60% or higher

How well did you know this?

Not at all

Perfectly

What virulence factor of Bacillus anthracis is carried by the plasmid?

Genes coding for the 
exotoxin protein (pX01) and
polypeptide capsule (pX02)

How well did you know this?

Not at all

Perfectly

Significance of the capsule of Bacillus anthracis

The capsule gives the virulence, non capsulated bacilli is non virulent

It is made up of poly-D glutamic acid, a protein, unlike other capsule which are made up of carbohydrates

Inhibits phagocytosis and interfere with opsonization

How well did you know this?

Not at all

Perfectly

Component of media needed to trigger the organism produce capsules

Serum or bicarbonate

mucoid colonies = capsule formation

How well did you know this?

Not at all

Perfectly

The three thermolabile components of Anthrax exotoxin complex

Factor 1 - Edema Factor - Edema
Factor 2 - Protective Factor - Antiphagocytic
Factor 3 - Lethal factor - Lethality

How well did you know this?

Not at all

Perfectly

What is the alpha and beta subunit of the Anthrax exotoxin

Alpha - Factor 1/Edema Factor

Beta - Factor 2/Protective Factor

How well did you know this?

Not at all

Perfectly

Mode of Action of Factor 1

Calcium regulated
Increases Camp
Causes fluid & electrolyte loss
Prevent entry of Na & Cl ions
Creates osmotic effect
Edema formation
(affects all cell of the body)

How well did you know this?

Not at all

Perfectly

Mode of Action of Factor 2

Promotes entry of edema factor and lethal factor

How well did you know this?

Not at all

Perfectly

Mode of Action of Factor 3

Inducing apoptosis of activated macrophages, LT could prevent the release of chemokines and cytokines that alert the immune system to the presence of infecting B. anthracis, thereby facilitating the systemic spread of the infection

no effect on other cells

Mode of Action of Anthrax Exotoxin Complex

PA binds & forms a heptamer to which EF and LF bind

Endocytosis and pH change causes fusion of PA with vesicle and release of LF and EF

Inhibit cell signaling and causes cell death

Pathogenicity of Bacillus anthracis in Cattle

Most frequently seen in Cattle
Acute septicemia is more common
Cutaneous form following contamination of abrasions or wounds is occasionally observed

Pathogenicity of Bacillus anthracis in Swine

Less susceptible than cattle
Subacute form; (Pharyngeal edema) pharyngitis with extensive swelling and hemorrhage in the region of neck and throat
Intestinal form with gastroenteritis also occurs

Pathogenicity of Bacillus anthracis in Dogs and Cats

Rare but resembles that of Swine (Pharyngeal Edema)

Pathogenicity of Bacillus anthracis in Humans

Malignant carbuncle or pustule (most common)
Pulmonary Anthrax (Woolsorter's Disease, localized in Macrophanges, mediastinal hemorrhage)
Intestinal Anthrax (Necrotic Lesions with abdominal pain)

Resistance of Vegetative cells of Bacillus anthracis

Vegetative cells in unopened carcasses may survive for up to 1-2 weeks (Killed at 60 C for 30 minutes)

Resistance of Spores of Bacillus anthracis

Spores can persist for decades in a stable, dry environment. Spores are relatively resistant to heat and chemicals

Heat fixation of smears doesn’t kill spores

Killed by autoclaving (121C/15 minutes) and dry heat (150C/60 minutes, but not by boiling(100C) for under 10 minutes

Resistance to disinfectants of Bacillus anthracis

Aldehydes, oxidizing and chlorinating disinfectant, ethylene oxide Hides, hair, wool, bones and animal products not treated sufficiently to kill the spores may remain ineffective for years

True or False: If anthrax is suspected, carcass should not be opened

True. Sporation can occur in abundant oxyegn and contaminate the air. Let carcass rot to kill vegetative vell because of acidic products

Sample collected for diagnosis in Septicemic form in cattle, sheep, and horses

Septicemic form. | Swabs from exuded blood or blood taken by syringe. Blood smears may also be submitted

Sample collected for diagnosis in localized form in swine

Swabs from the cut surface of hemorrhagic lymph nodes or fluid or exudates aspirated from affected lymph nodes if the organism cannot be demonstrated in blood smears

Stain used for the direct examination of Bacillus anthracis

Smears from tissues or blood contained from a superficial vein are stained with Gram's, Giemsa's, or Wright's stain (large, square-ended, gram-positive rods suggests anthrax) stain with fluorescent antibodies against the cell wall or capsule of B. anthracis

Expected appearance of Bacillus anthracis in isolation (blood agar, nutrient agar, microscopic examination)

Blood agar: colonies appear within 24 hours and are flat, rough, grey, and non-hemolytic Nutrient agar: Colonies could be smooth and mucoid or rough (ground glass appearance Microscopic examination: the edges of the colonies appear as a tangled mass of curly hairs (medusa head/judge's wig)

Bacillus species resembling Bacillus anthracis are called?

Anthracoids (e.g. B. subtilis, B. cereus, B. licheniformis, B megaterium, B. thuringiensis)

Explain the Mcfadyean's reaction

anthrax organism appears as blue color rods in pink stained amorphous polyglutamic acid capsule

Explain the Ascoli test

Precipitation reaction. Used to detect anthrax in decomposed carcasses.

Explain the String of Pearls test

Based on the principle of impairment of cell wall development by penicillin Due to cell wall impairment it will produce colonies which will resemble string of pearls

Antibiotic used against Bacillus anthracis

Penicillin

What is a Stern Strain Vaccine

A live attenuated spore vaccine. With px01, but no px02 (no capsule=not pathogenic)

What is a Anthrax Vaccine Adsorbed (AVA)?

Cell free filtrate of anthrax. Toxigenic but not capsulated

Bacillus cereus

Bovine - gangrenous bovine mastitis | Cows and ewes - abortion

Bacillus subtilis

Man - occasionally conjunctivitis

Bacillus licheniformis

Bovine & ovine - abortion (but not the main cause)

Geobacillus stearothermophilus

used to test the efficacy of autoclaving and other sterilizing procedure

Bacillus piliformis

Tyzzer's Disease Gram negative, intracellular organism