Anaerobic infections

Question 1

What is an anaerobic organism?

Answer 1

One that cannot survive in an oxygen environment

Question 2

What is a facultative anaerobe?

Answer 2

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

Question 3

Give two gram negative anaerobic bacillus’

Answer 3

• Bacteriodes
• Fusobacterium

Question 4

Give a gram negative anaerobic coccus

Answer 4

Veillonella

Question 5

Give a gram positive anaerobic bacillus

Answer 5

Clostridium

Question 6

Give a gram positive anaerobic coccus

Answer 6

Anaerobic streptococci

Question 7

What are the clostridia species?

Answer 7

A spore forming Gram positive bacilli

Question 8

Where are clostridia found?

Answer 8

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

Question 9

How many species of clostridia are there?

Answer 9

Around 80, but few that are disease causing

Question 10

What does the clostridia pathophysiology involve?

Answer 10

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

Question 11

Where is clostridium difficile found?

Answer 11

In the human GI tract as microbiota

Question 12

What % of the GI tract microbiota is clostridium difficle?

Answer 12

~3% in adults

Question 13

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

Answer 13

Children and neonates, and hospitalised patients

Question 14

Why do hospitalised patients have more C. Difficile?

Answer 14

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

Question 15

What does C. Difficile produce?

Answer 15

Two toxins;

• A
• B

Question 16

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

Answer 16

Act on the gut to cause a mass release of cytokines

Question 17

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

Answer 17

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

Question 18

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

Answer 18

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

Question 19

What do individuals infected with C. Difficile develop?

Answer 19

• C. Difficile related diarrhoea
• Abdominal pain
• Malaise
• Fever
• Nausea

Question 20

What can the inflammation from C. Difficile infection cause?

Answer 20

The stopping of bowel peristalsis

Question 21

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

Answer 21

‘Toxic megacolon’

Question 22

What can toxic megacolon lead to?

Answer 22

Bowel perforation and septicaemia

Question 23

How is diagnosis of C. Difficile made?

Answer 23

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

Question 24

What does treatment of C. Difficile involve?

Answer 24

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

Question 25

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

Answer 25

* Hand-washing of health care workers * Individuals should be isolated in side rooms

Question 26

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

Answer 26

Alcohol hand gel is ineffective against the spores

Question 27

What is the main cause of gas gangrene?

Answer 27

Clostridium Perfringes

Question 28

What kind of bacteria is clostridium perfringes?

Answer 28

Gram positive bacillus

Question 29

Where is clostridium perfringes found?

Answer 29

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

Question 30

Other than gas gangrene, what can clostridium perfringes cause?

Answer 30

Food poisioning

Question 31

When can clostridium perfringes cause food poisioning?

Answer 31

When poorly cooked meats are consumed

Question 32

What does gas gangrene develop from?

Answer 32

A devitalised wound

Question 33

What is meant by a devitalised wound?

Answer 33

One with interruption to the blood supply

Question 34

How does C. Perfringes cause gas gangrene?

Answer 34

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

Question 35

What toxins are released by C. Perfringes?

Answer 35

Mainly α-toxins

Question 36

What does gas gangrene cause?

Answer 36

Extensive damage to the surrounding soft tissue

Question 37

Why is gas gangrene so named?

Answer 37

Gas slowly collects under the skin due to metabolising anaerobes

Question 38

What does treatment of gas gangrene involve?

Answer 38

Debridement of the devitalised tissue and intravenous antibiotics

Question 39

What antibiotics are given in gas gangrene?

Answer 39

Mainly penicillin

Question 40

What is the causative agent for tetanus?

Answer 40

Colstridium tetani

Question 41

What is the main symptom of tetanus?

Answer 41

Spastic paralysis

Question 42

Where do tetanus infections occur?

Answer 42

In wounds deep enough to cause anaerobic conditions

Question 43

What happens in a tetanus infection?

Answer 43

C. Tetani spores cause tetanospasmin

Question 44

What does tetanospasmin do?

Answer 44

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

Question 45

What is the result of tetanus induced GABA release inhibition?

Answer 45

Spastic paralysis at the site of injury

Question 46

How can tetanus be diagnosed?

Answer 46

From history and clinical features

Question 47

What does treatment of tetanus involve?

Answer 47

* Muscle relaxant * Immunisation * Antibiotics

Question 48

What are the types of vaccine for tetanus?

Answer 48

* Active * Passive *

Question 49

What is given in active immunisation against tetanus?

Answer 49

Tetanus toxoid

Question 50

What is given in passive immunisation against tetanus?

Answer 50

Human tetanus Ig

Question 51

What causes botulism?

Answer 51

Clostridium botulinum

Question 52

What is the main symptom of botulism?

Answer 52

Flaccid paralysis

Question 53

Where is C. Botulinum widely distributed?

Answer 53

As a saprophyte in soil, food, etc

Question 54

Why is C. Botulinum hard to get rid of?

Answer 54

Its spores resist destruction by heat

Question 55

What can result in botulism poisoning?

Answer 55

Incomplete heating in the canning or bottling process

Question 56

What is the botulism toxin?

Answer 56

A neurotoxin

Question 57

What does the botulism toxin do?

Answer 57

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

Question 58

How do patients with botulism present?

Answer 58

* Descending flaccid paralysis * Dysphagia * Blurred vision * Eventual general paralysis

Question 59

What does treatment of botulism involve?

Answer 59

* Antitoxins, * Penicillin as the antibiotic * Ventilatory support

Question 60

What do non-sporing anaerobes form?

Answer 60

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

Question 61

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

Answer 61

Endogenous

Question 62

How do infections of non-sporing anaerobes occur?

Answer 62

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

Question 63

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

Answer 63

Perforation of the large intestine

Question 64

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

Answer 64

They can multiply and cause tissue damage and spread

Question 65

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

Answer 65

* Intra-abdominal abscesses * Liver abscesses * Lung abscesses * Dental abscess * Bone abscess * Leg ulceration

Question 66

How do non-sporing anaerobes cause lung abscesses?

Answer 66

From aspiration pneumonia and subsequent formation of anaerobic compartment

Question 67

What commonly happens with infection with non-sporing anaerobes?

Answer 67

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

Question 68

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

Answer 68

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

Question 69

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

Answer 69

Metronidazole

Question 70

What are the main pathogens of anaerobic sepsis?

Answer 70

* Bacteriodes fragilis * Prevotella melaninogenicus

Question 71

Why is bacteriodes fragilis clinically relevant?

Answer 71

It is the most common of serious anaerobic infections

Question 72

What is bacteriodes fragilis most commonly associated with?

Answer 72

Post-operative sepsis in abdominal or gynacological surgery

Question 73

What feature does bacteriodes fragilis have?

Answer 73

Antiphagocytic capsule

Question 74

What is the result of bacteroides fragilis' antiphagocytic capsule?

Answer 74

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

Question 75

Where is Prevotella melaninogenicus common?

Answer 75

In dental abscesses and sinus infections