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Z Old Infection IGNORE > Anaerobic infections > Flashcards

Anaerobic infections Flashcards

1
Q

What is an anaerobic organism?

A

One that cannot survive in an oxygen environment

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2
Q

What is a facultative anaerobe?

A

One that can grow partially in small levels of oxygen, so is not a true anaerobic organism

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3
Q

Give two gram negative anaerobic bacillus’

A
  • Bacteriodes
  • Fusobacterium
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4
Q

Give a gram negative anaerobic coccus

A

Veillonella

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5
Q

Give a gram positive anaerobic bacillus

A

Clostridium

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6
Q

Give a gram positive anaerobic coccus

A

Anaerobic streptococci

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7
Q

What are the clostridia species?

A

A spore forming Gram positive bacilli

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8
Q

Where are clostridia found?

A

In soil and water, but also ubiquitous as part of normal human microbiota

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9
Q

How many species of clostridia are there?

A

Around 80, but few that are disease causing

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10
Q

What does the clostridia pathophysiology involve?

A

Entering the anaerobic conditions as spores, germinating to form large numbers, and then releasing toxins to act as the main pathogenic factor

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11
Q

Where is clostridium difficile found?

A

In the human GI tract as microbiota

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12
Q

What % of the GI tract microbiota is clostridium difficle?

A

~3% in adults

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13
Q

Who has a higher % of clostridium difficile in the GI tract microbiota?

A

Children and neonates, and hospitalised patients

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14
Q

Why do hospitalised patients have more C. Difficile?

A

Because the use of broad-spectrum antibiotics will massively alter the GI microbiota, allowing for any endogenous C. Difficile to proliferate, or for an exogenous infection due to large numbers of patients releasing clostridium spores into the environment which can then colonise the GI tract

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15
Q

What does C. Difficile produce?

A

Two toxins;

  • A
  • B
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16
Q

What do the A and B toxins produced by C. Difficile do?

A

Act on the gut to cause a mass release of cytokines

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17
Q

What does the release of cytokines due to C. Difficile cause?

A

Tissue damage and death, and the subsequent formation of a pseudomembrane

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18
Q

Why is it not a problem for neonates to carry large amounts of C. Difficile in their gut?

A

Because the lack of receptors for these toxins mean they can’t take an effect

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19
Q

What do individuals infected with C. Difficile develop?

A
  • C. Difficile related diarrhoea
  • Abdominal pain
  • Malaise
  • Fever
  • Nausea
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20
Q

What can the inflammation from C. Difficile infection cause?

A

The stopping of bowel peristalsis

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21
Q

What can the stopping of bowel peristalsis related to C. Difficile lead to?

A

‘Toxic megacolon’

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22
Q

What can toxic megacolon lead to?

A

Bowel perforation and septicaemia

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23
Q

How is diagnosis of C. Difficile made?

A

From a stool sample, checking for antigen detection or toxin detection

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24
Q

What does treatment of C. Difficile involve?

A
  • Oral metrinidazole or vancomycinD
  • iscontinuing of the current antibiotic regime if possible
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25
Q

What is vital to prevent the spreads of C. Difficile spores?

A
  • Hand-washing of health care workers
  • Individuals should be isolated in side rooms
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26
Q

Why must healthcare workers wash their hands to prevent the spread of C. Difficile?

A

Alcohol hand gel is ineffective against the spores

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27
Q

What is the main cause of gas gangrene?

A

Clostridium Perfringes

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28
Q

What kind of bacteria is clostridium perfringes?

A

Gram positive bacillus

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29
Q

Where is clostridium perfringes found?

A

As part of the intestinal microbiota, but its spores are found everywhere in the environment

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30
Q

Other than gas gangrene, what can clostridium perfringes cause?

A

Food poisioning

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31
Q

When can clostridium perfringes cause food poisioning?

A

When poorly cooked meats are consumed

32
Q

What does gas gangrene develop from?

A

A devitalised wound

33
Q

What is meant by a devitalised wound?

A

One with interruption to the blood supply

34
Q

How does C. Perfringes cause gas gangrene?

A

The spores are taken in from the environment via the wound, and they germinate in the anaerobic wound and release toxins in the ischaemic conditions

35
Q

What toxins are released by C. Perfringes?

A

Mainly α-toxins

36
Q

What does gas gangrene cause?

A

Extensive damage to the surrounding soft tissue

37
Q

Why is gas gangrene so named?

A

Gas slowly collects under the skin due to metabolising anaerobes

38
Q

What does treatment of gas gangrene involve?

A

Debridement of the devitalised tissue and intravenous antibiotics

39
Q

What antibiotics are given in gas gangrene?

A

Mainly penicillin

40
Q

What is the causative agent for tetanus?

A

Colstridium tetani

41
Q

What is the main symptom of tetanus?

A

Spastic paralysis

42
Q

Where do tetanus infections occur?

A

In wounds deep enough to cause anaerobic conditions

43
Q

What happens in a tetanus infection?

A

C. Tetani spores cause tetanospasmin

44
Q

What does tetanospasmin do?

A

Prevents release of inhibitory transmitter γ-aminobutyric acid (GABA)

45
Q

What is the result of tetanus induced GABA release inhibition?

A

Spastic paralysis at the site of injury

46
Q

How can tetanus be diagnosed?

A

From history and clinical features

47
Q

What does treatment of tetanus involve?

A
  • Muscle relaxant
  • Immunisation
  • Antibiotics
48
Q

What are the types of vaccine for tetanus?

A
  • Active
  • Passive
    *
49
Q

What is given in active immunisation against tetanus?

A

Tetanus toxoid

50
Q

What is given in passive immunisation against tetanus?

A

Human tetanus Ig

51
Q

What causes botulism?

A

Clostridium botulinum

52
Q

What is the main symptom of botulism?

A

Flaccid paralysis

53
Q

Where is C. Botulinum widely distributed?

A

As a saprophyte in soil, food, etc

54
Q

Why is C. Botulinum hard to get rid of?

A

Its spores resist destruction by heat

55
Q

What can result in botulism poisoning?

A

Incomplete heating in the canning or bottling process

56
Q

What is the botulism toxin?

A

A neurotoxin

57
Q

What does the botulism toxin do?

A

Prevents the release of acetylcholine at the NMJ, thus preventing muscle contraction

58
Q

How do patients with botulism present?

A
  • Descending flaccid paralysis
  • Dysphagia
  • Blurred vision
  • Eventual general paralysis
59
Q

What does treatment of botulism involve?

A
  • Antitoxins,
  • Penicillin as the antibiotic
  • Ventilatory support
60
Q

What do non-sporing anaerobes form?

A

The major part of the human bacterial flora of the mouth, intestine, vagina, and skin

61
Q

What kind of infections are those by non-sproring anaerobes?

A

Endogenous

62
Q

How do infections of non-sporing anaerobes occur?

A

Organisms escape from the normal flora into a new sterile anaerobic site

63
Q

Give an example of how an infection of a non-sporing anaerobe could occur

A

Perforation of the large intestine

64
Q

What happens once non-sporing anaerobes are established in their infective site?

A

They can multiply and cause tissue damage and spread

65
Q

What are the main endogenous infections caused by non-sporing anaerobes?

A
  • Intra-abdominal abscesses
  • Liver abscesses
  • Lung abscesses
  • Dental abscess
  • Bone abscess
  • Leg ulceration
66
Q

How do non-sporing anaerobes cause lung abscesses?

A

From aspiration pneumonia and subsequent formation of anaerobic compartment

67
Q

What commonly happens with infection with non-sporing anaerobes?

A

They mix with aerobic bacteria and produce foul-smelling pus, which is quite characteristic

68
Q

How is diagnosis of infection with non-sporing anaerobes made?

A

From spending specimens to the laboratory in anaerobic containers, and the cultures grown in selective media and under strict anaerobic conditions. The cultures can then be stained accordingly

69
Q

What are the infections caused by non-sporing anaerobes mainly susceptible do?

A

Metronidazole

70
Q

What are the main pathogens of anaerobic sepsis?

A
  • Bacteriodes fragilis
  • Prevotella melaninogenicus
71
Q

Why is bacteriodes fragilis clinically relevant?

A

It is the most common of serious anaerobic infections

72
Q

What is bacteriodes fragilis most commonly associated with?

A

Post-operative sepsis in abdominal or gynacological surgery

73
Q

What feature does bacteriodes fragilis have?

A

Antiphagocytic capsule

74
Q

What is the result of bacteroides fragilis’ antiphagocytic capsule?

A

It inhibits phagocytosis of facultative organisms, promoting the development of synergistic infections

75
Q

Where is Prevotella melaninogenicus common?

A

In dental abscesses and sinus infections

Z Old Infection IGNORE (23 decks)

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