Bacillus

Question 1

T/F: Anthrax can and has been used as a bioweapon

Answer 1

TRUE

Question 2

What is the habitat of Bacillus spp?

Answer 2

saprophytes - dead or decaying organic matter, endospores allow for environmental persistence

Question 3

What are the favorable soil conditions for Bacillus spp?

Answer 3

high moisture content, alkaline, rich in calcium and nitrogen

Question 4

What species of Bacillus are important in veterinary medicine?

Answer 4

B. anthracis, B. cereus, B. licheniformis

Question 5

What are some general characteristics of Bacillus spp?

Answer 5

gram-positive motile endospore-producing rods, aerobes or facultative anaerobes, catalase-positive and oxidase-negative, grow on non-enriched media,non-pathogenic

Question 6

How do outbreaks of B. anthracis in herbivores occur?

Answer 6

pasture contamination by spores from buried animals, spores brought to surface by floor, excavation, subsidence

Question 7

How do sporadic outbreaks of B. anthracis occur?

Answer 7

importation of contaminated meat- and bone-meal, fertilizers of animal origin, hides. raw/poorly-cooked contaminated meat fed to animals/people

Question 8

How is B. anthracis transmitted?

Answer 8

mainly ingestion, inhalation, skin abrasions

Question 9

What is the species susceptibility of B. anthracis?

Answer 9

ruminants > > > > horses > pigs > carnivores > birds (resistant)

Question 10

What are the virulence factors of B. anthracis regulated by?

Answer 10

host temperature and CO2 concentration

Question 11

What are the two major virulence factors of B. anthracis?

Answer 11

complex toxin, poly-y-D glutamic acid capsule

Question 12

What is complex toxin encoded by?

Answer 12

pX01

Question 13

What is poly-y-D glutamic acid capsule encoded by?

Answer 13

pX02

Question 14

What are the three antigenic components of complex toxins?

Answer 14

protective antigen (host cell-binding portion for EF and LF), edema factor (an adenylyl cyclase enzyme), lethal factor (a zinc metalloprotease)

Question 15

What are the effects of edema toxin?

Answer 15

increases cAMP, disturbs water homeostasis, accumulates fluid, targets neutrophils

Question 16

What are the effects of lethal toxin?

Answer 16

causes death in macrophages, dendritic cells, neutrophils, and epithelial cells

Question 17

What is the pathogenesis of B. anthracis?

Answer 17

cutaneous, intestinal, or pulmonary entry of spores -> regional lymph node -> regional hemorrhagic lymphadenitis -> septicemia or pulmonary lymphatic blockage -> meningitis or pulmonary edema -> death

Question 18

What is the incubation period of B. anthracis?

Answer 18

3-7 days but ranges from 1-14 days

Question 19

What are the clinical signs of B. anthracis in cattle and sheep?

Answer 19

death in animals with no premonitory signs, septicemia and rapidly fatal, pyrexia (fever), depression, congestion of mucosae

Question 20

What are some post-mortem findings of cattle and sheep affected by B. anthracis?

Answer 20

rapid bloating, incomplete rigor mortis, ecchymotic hemorrhages, edema, dark, unclotted blood, blood-stained fluid in body cavities, enlarged soft spleen

Question 21

T/F: necropsy of animals with anthrax is usually advised

Answer 21

FALSE

Question 22

What are the major clinical signs of B. anthracis in pigs?

Answer 22

sudden death after ingestion, regional lymphadenitis (edematous swelling of throat/head ), intestinal dysentery (less common)

Question 23

What are the major clinical signs of B. anthracis in carnivores?

Answer 23

resembles that of pigs

Question 24

What are the major clinical signs of B. anthracis in herbivores?

Answer 24

resembles that of cattle

Question 25

What are the major clinical signs of B. anthracis in horses?

Answer 25

extensive subcutaneous lesions, localized edema, septicemia with colic and dysentery

Question 26

What does the cutaneous form of anthrax present as in humans?

Answer 26

localized lesions, itchy, red, dark blisters

Question 27

What does the pulmonary/inhalation form of anthrax (woolsorters' disease) present as in humans?

Answer 27

fever, pain, malaise, death in 1-7 days

Question 28

What does the intestinal form of anthrax present as in humans?

Answer 28

death from contaminated meat

Question 29

How do you diagnose anthrax?

Answer 29

blood sample (tail vein of ruminants or peritoneal fluid), MacFadyean reaction with polychrome methylene blue stain Loeffler's stain, culture, PCR, fluorescent antibody technique, western blot and ELISA

Question 30

What are the major microscopic characteristics of B. anthracis?

Answer 30

edge of colony has medusa hair appearance, spores stain with malachite green

Question 31

What are some cultural characteristics of B. anthracis on nutrient agar?

Answer 31

irregularly round, raised, dull, and opaque colonies, frosted glass appearance

Question 32

What are the major cultural characteristics of B. anthracis on blood agar with penicillin?

Answer 32

non-hemolytic

Question 33

What test is utilized to diagnose B. anthracis in tissues?

Answer 33

ascoli's test

Question 34

T/F: B. anthracis grows on MAC agar

Answer 34

FALSE

Question 35

How do you conduct an ascoli's test?

Answer 35

2-3g of homogenized tissue in saline is boiled and filtered, filtrate used as an antigen in ring precipitation or gel diffusion test with specific antiserum

Question 36

What are some general characteristics of B. anthracis spores?

Answer 36

require poor nutrient conditions and oxygen, very resistant to extremes and can survive for ~50 years, resistant to disinfectants and desiccation, lethal dose starting at 2,500 spores

Question 37

How do you treat anthrax?

Answer 37

high doses of pencillin G or oxytetracycline

Question 38

How do you control anthrax in endemic regions?

Answer 38

immediately report to authorities, annual vaccinations in cattle and sheep, killed vaccines in humans, chemoprophylaxis with long-acting penicillin

Question 39

How do you control anthrax in non-endemic regions following an outbreak?

Answer 39

stop movement of animals, their waste, and bedding, wear PPE, sporicidal footbaths on farms, sanitization of contaminated buildings, incinerate carcasses, waste, and bedding, prevention of scavenger animals, isolation and observation of exposed animals

Question 40

Where is B. cereus found?

Answer 40

soil, grains, vegetables, raw and processed foods

Question 41

What is usually associated with B. cereus in animals?

Answer 41

embryonic death, abortion, and abnormal fetal development

Question 42

What is usually associated with B. cereus in humans?

Answer 42

eye infections, foodborne intoxications, emetic syndrome, diarrheal syndrome

Question 43

Where is B. licheniformis found?

Answer 43

environment, slurry, silage, and water troughs

Question 44

What does B. licheniformis cause in cattle and sheep?

Answer 44

sporadic abortions

Question 45

Where is B. licheniformis most commonly found?

Answer 45

housed, pit-silage-fed, spring calving beef cows last 2 months of pregnancy

Question 46

T/F: Bacillus spp are large gram-positive rods

Answer 46

TRUE

Question 47

T/F: B. anthracis is non-hemolytic in blood agar

Answer 47

TRUE

Question 48

T/F: The genes of exotoxin production in B. anthraxis are present on bacterial chromosome

Answer 48

FALSE

Question 49

T/F: veterinarians must always perform post-mortems on animals suspected to have died from anthrax

Answer 49

FALSE

Question 50

T/F: B. anthracis does not produce capsules

Answer 50

FALSE

Question 51

T/F: the protective antigen (PA) acts as a binding site for edema factor and lethal factor

Answer 51

TRUE

Question 52

T/F: edema toxins target neutrophils

Answer 52

TRUE