M3: Anaerobic Bacteria

Question 1

What is an obligate anaerobe?

Answer 1

• Organisms unable to grow in presence of O2

- Require low reduction/oxidation potential

Question 2

What is an facultative anaerobe?

Answer 2

• Organisms which grow under aerobic or anaerobic conditions

e. g. E. coli, staphylococci, streptococci

Question 3

What is an microaerophile?

Answer 3

• Organisms that require a small amount of O2

e. g. Campylobacter, Helicobacter

Question 4

What is an capnophile?

Answer 4

• Organisms that require 5 – 10% CO2 for growth

e. g. Brucella, Capnocytophaga

Question 5

Describe the vacuum replacement method of cultivating anaerobes in anaerobic jars

Answer 5

• Remove air with vacuum pump
• Replace atmosphere with gas mix
  (e. g. 80% N2, 10% H2, 10% CO2 )
• Include palladium catalyst

Question 6

Describe the Gas-Generating Sachets of cultivating anaerobes in anaerobic jars

Old method?
New method?

Answer 6

OLD METHOD

• Add water to sachet
• Generates H2 + CO2
• Include catalyst

NEW METHOD

• Add anaerogen sachets
• O2 absorbed and CO2 produced
• No catalyst need and No water added.

Question 7

Describe how you cultivate anaerobes in an anaerobic cabinet

Answer 7

• Provides complete working chamber for anaerobes
• Contains atmosphere of 80% N2 10% H2 10% CO2
• Pass materials in and out via air lock

Question 8

Describe how you cultivate anaerobes in an Robertons Cooked Meat (RCM) Medium.

Answer 8

Contains pieces of fat-free minced cooked meat of ox heart and nutrient broth which cultivates anaerobes

Question 9

What is Peptostreptococcus?

Answer 9

Cocci gram positive anaerobe

Question 10

Give an example of a clinically important spore forming gram positive anaerobe

Answer 10

Clostridium

Question 11

Give an example of a clinically important non spore forming gram positive anaerobe

Answer 11

Actinomyces

Question 12

What is Veillonella?

Answer 12

Cocci gram negative anaerobe

Question 13

Give examples of gram negative rod and filament anaerobes (5)

Answer 13

• Bacteriodes
• Fusobacterium
• Porphyromonas
• Prevotella
• Campylobacter

Question 14

Give 2 examples of spirochaetes

Answer 14

• Spirochaeta

- Treponema

Question 15

What are Dentoalveolar/Periapical Abscesses?

Answer 15

Abscesses that develop around apices of teeth with necrotic and infected root canals

Question 16

What organisms are involved in dentoalveolar abscess

Answer 16

Oral streptococci and many oral anaerobes

Question 17

What is Osteomyelitis?

What is it caused by?

Answer 17

Rare disease causing inflammation of the jaw bone cavity

Anaerobic gram negative rods and Streptococcus

Question 18

What is Chronic Marginal Gingivitis?

Answer 18

Inflammation confined to the soft tissues of the gingival as a result of dental plaque accumulation
(no particular species of bacteria involved)

Question 19

What is acute ulcerative gingivitis?

What causes this?

Answer 19

• Grey gingival pseudomembrane, which is easily removed to reveal a bleeding area, and destruction of the interdental papillae
• Spirochaetes , Prevotella intermedia and Fusobacterium spp.

Question 20

What is Pericoronitis?

Answer 20

Inflammation of the soft tissues that surround the crown of a partially erupted tooth esp. mandibular third molars

Oral anaerobes including P. intermedia & Fusobacterium nucleatum

Question 21

What is Peri-implantis?

What causes this?

Answer 21

Inflammation around implant systems that replace missing teeth

Oral anaerobes esp P. gingivalis and P. intermedia

Question 22

What is Actinomycosis?

What causes this?

Answer 22

Formation of a chronic granuloma with swelling

Actinomyces israelii

Question 23

What is Sialadenitis?

What causes this?

Answer 23

Infection of the salivary glands

Streptococcus spp., Staphylococcus aureus

Question 24

infections with non sporing anaerobes are commonly polymicrobial what does this mean?

Answer 24

Mixture of anaerobes and other organisms

Question 25

Describe the clinical presentation of infections with non sporing anaerobes

Answer 25

• Often found in abscesses and wound infections
• May be associated with foul-smelling pus or
  discharge

Question 26

What are the general features of clostridium? (4)

Answer 26

• Gram positive large anaerobic rods
• Produce endospores – enable organisms to survive adverse conditions e.g. soil and on skin
• Found in human and animal intestine, soil,
  water, decaying animal & plant matter
• Pathogenic species produce potent exotoxins

Question 27

Tetanus;

Type of infection?
Caused by?
Results from?
Where does the spores arise?

Answer 27

• Clostridal infection
• Caused by Clostridium tetani
• Usually follows from contamination of deep wound injury
• Spores in soil and general environment

Question 28

Clinical presentation of tetanus? (4)

Answer 28

• Causes trismus (lockjaw)
• Dysphagia
• Muscle spasms
• Death by respiratory or cardiac failure

Question 29

Botulism

Type of infection?
What causes?
How does it occur?
How does it work?

Answer 29

• Caused by Clostridium botulinum
• Follows ingestion of pre-formed toxin in food
• Produces extremely potent neurotoxins (types A-G)
• Human botulism caused by types A, B & E
• Toxin blocks release of acetylcholine from peripheral motor nerve endings

Question 30

Clinical presentation of botulism (4)

Answer 30

• Vomiting
• Thirst
• Muscle paralysis
• Death by respiratory or cardiac failure

Question 31

Gas gangrene

Type of infection?
Caused by?
Species involved?

Answer 31

• Usually polymicrobial infection of wounds
• Caused by histotoxic clostridia that produce a range of lethal and necrotising toxins
• Several species of clostridia may be involved

Question 32

What are Clostrodial toxins?

Answer 32

• Many Clostridium species produce potent exotoxins
• Some can be made into toxoids
• All are proteins and are antigenic

Question 33

What is naglers reaction?

Answer 33

When Clostridium perfringens is grown in a medium containing egg yolk (lecithin) the enzyme (lecithinase) activity can be detected as opacity around the line of growth.