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BACTERIOLOGY > Aerobic Spore-forming, Gram positive bacili > Flashcards

Aerobic Spore-forming, Gram positive bacili Flashcards

1
Q

Charcateristic of Bacillus spp in general

A
  • gram positive rods
  • aerobic or facultative aerobic
  • catalase (+); form non-pigmented colonies
  • grow well in Sheep blood agar (or in enriched agars)
  • non-branching
  • sporulating (endospore - inactive form)
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2
Q

True or False:

Endospores are naturally active in the bacteria

A

False

  • they only become active once they detect something that might possibly kill the bacteria
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3
Q

Bacillus spp can sometimes be confused with these bacteria

A

Clostridium

  • since they are also gram-positive; spore-formin rods but are usually ANAEROBIC
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4
Q

Bacillus and Clostridium spp. can be differentiated by

A

Both - gram (+)

Catalase
Clostridium (-)
Bacillus (+)

Sporulation
Clostridium - anaerobic only
Bacillus - Anaerobic and aerobic

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5
Q

Best way to differentiate Clostridium spp from Bacillus spp.

A

Catalase testing

Catalase
Clostridium (-)
Bacillus (+)

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6
Q

Bacillus spp:

Bacillus cerues sensu lato group

A
  • B. anthracis
  • B. cereus sensu stricto
  • B. thuringiensis
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7
Q

Bacillus spp. that is considered the most medically important, since it is considered a potential bioterrorism agent

A

B. anthracis

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8
Q

Bacillus spp: B. anthracis

Culture characteristics

A
  • nonhemolytic - ground glass colonies on SBA
  • nonmotile; encapsulated
  • large, gray, flat with swirling preojections — “MEDUSA head”
  • beaten egg white consistency of colonies
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9
Q

Causative agent of ANTHRAX ( a zoonotic disease) usully found in herbivores

A
  • B. anthracis
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10
Q

B. anthracis:

Virulence factors

A
  • capsule (D-glutamic acid)

- anthrax toxin

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11
Q

Capsule of B. anthracis can be visualized using

A

M’ Fadyean staining with methylene blue or India ink staining

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12
Q

The anthrax toxin of B. anthracis is made up of what proteins

A
  • Protective antigen (PA)
  • Edema factor (EF)
  • Lethal factor (LF)

PA+ EF = edema
PA +LF = death

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13
Q

Bacillus spp: B. cereus

Culture characteristics

A
  • beta-hemolytic on SBA
  • nonecapsulated & motile
  • Y - zone on egg yolk agar
  • penicillin-resistant
  • feathery and spreading resembling frosted glass
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14
Q

Bacillus spp. that often causes food poisoning and serious agentt of eye infections.

A
  • B. cereus
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15
Q

B. cereus:

Virulence factors

A
  • diarrheal enterotoxins

- emetic enterotoxin (cereulide)

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16
Q

A heat stable toxin produced by B. cereus which often cause nausea and vomitting in host.

A
  • Emetic enterotoxin
17
Q

Culture characteristics used to differentiate B. antracis to B.cereus

A
  • Hemolysis on SBA
  • Motility
  • Resistance to penicillin

B. anthracis

  • nonhemolytic
  • nonmotile
  • penicillin (S)

B.cereus

  • beta-hemolytic
  • motile
  • penicillin (R)
18
Q

True or False

B. anthracis is a potential terrorism thus they must be ruled out when isolated in clinical specimen

A
  • TRUE
19
Q

4 forms of Anthrax

A
  • cutaneous
  • inhalation
  • gastrointestinal
  • injectional anthrax
20
Q

A form of Anthrax sonisdered as the most predominant form of anthrax and characterized by black “ESCHAR”

A
  • cutaneous anthrax

acquired thru skin cuts, wounds,and insect bites

21
Q

It is characterized by dark, crusty tissue at either the bottom or the top of a wound

A

ESCHAR

a derpressed black necrotic central area

22
Q

A form anthrax also called as Woolsorter’s disease or Ragpicker’s disease

A
  • Inhalation/ Pulmonary anthrax
23
Q

True or False:

Injectional anthrax is associated with fomarion of eschar and is usually caused by drug abuse

A

FALSE

  • no black eschar is seen
24
Q

All about Food poisoning or diarrheal symptom caused by B.cereus

A
  • incubation period 8-16 hrs
  • duration 12-14 hrs
  • ingestion of meat, poultry, vegetables , and pastas
25
Q

Laboratory diagnosis:

B. anthracis

A

-gram (+) or gram-variable
“BAMBOO” rods
- clear xones may appear around cell indicating presence of capsule.

26
Q

Laboratory diagnosis:

B. cereus

A
  • similar to anthracis but without clear zone around cells since it’s not capsulated
27
Q

Presumptive ID of anthrax

A
  • stool culture in PEA, SBA. etc
28
Q

B.cereus needs quantitative culture os suspected animal in cases of food poisoning

A

≥ 10 to the power of 5 = presumptive of B.cereus food poisoning

29
Q

True or False

B.cereus can be accurately made thru stool cultures

A
  • FALSE

we cannot use stool culture since this maybe part of noral gut flora.

Quantitative identificatio is used

30
Q

Confirmation for ID of bacillus spp.

A
  • direct flourescent antibody assays

BACTERIOLOGY (15 decks)

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