M3: Anaerobic Bacteria Flashcards
What is an obligate anaerobe?
- Organisms unable to grow in presence of O2
- Require low reduction/oxidation potential
What is an facultative anaerobe?
- Organisms which grow under aerobic or anaerobic conditions
e. g. E. coli, staphylococci, streptococci
What is an microaerophile?
- Organisms that require a small amount of O2
e. g. Campylobacter, Helicobacter
What is an capnophile?
- Organisms that require 5 – 10% CO2 for growth
e. g. Brucella, Capnocytophaga
Describe the vacuum replacement method of cultivating anaerobes in anaerobic jars
- Remove air with vacuum pump
- Replace atmosphere with gas mix
(e. g. 80% N2, 10% H2, 10% CO2 ) - Include palladium catalyst
Describe the Gas-Generating Sachets of cultivating anaerobes in anaerobic jars
Old method?
New method?
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.
Describe how you cultivate anaerobes in an anaerobic cabinet
- Provides complete working chamber for anaerobes
- Contains atmosphere of 80% N2 10% H2 10% CO2
- Pass materials in and out via air lock
Describe how you cultivate anaerobes in an Robertons Cooked Meat (RCM) Medium.
Contains pieces of fat-free minced cooked meat of ox heart and nutrient broth which cultivates anaerobes
What is Peptostreptococcus?
Cocci gram positive anaerobe
Give an example of a clinically important spore forming gram positive anaerobe
Clostridium
Give an example of a clinically important non spore forming gram positive anaerobe
Actinomyces
What is Veillonella?
Cocci gram negative anaerobe
Give examples of gram negative rod and filament anaerobes (5)
- Bacteriodes
- Fusobacterium
- Porphyromonas
- Prevotella
- Campylobacter
Give 2 examples of spirochaetes
- Spirochaeta
- Treponema
What are Dentoalveolar/Periapical Abscesses?
Abscesses that develop around apices of teeth with necrotic and infected root canals
What organisms are involved in dentoalveolar abscess
Oral streptococci and many oral anaerobes
What is Osteomyelitis?
What is it caused by?
Rare disease causing inflammation of the jaw bone cavity
Anaerobic gram negative rods and Streptococcus
What is Chronic Marginal Gingivitis?
Inflammation confined to the soft tissues of the gingival as a result of dental plaque accumulation
(no particular species of bacteria involved)
What is acute ulcerative gingivitis?
What causes this?
- Grey gingival pseudomembrane, which is easily removed to reveal a bleeding area, and destruction of the interdental papillae
- Spirochaetes , Prevotella intermedia and Fusobacterium spp.
What is Pericoronitis?
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
What is Peri-implantis?
What causes this?
Inflammation around implant systems that replace missing teeth
Oral anaerobes esp P. gingivalis and P. intermedia
What is Actinomycosis?
What causes this?
Formation of a chronic granuloma with swelling
Actinomyces israelii
What is Sialadenitis?
What causes this?
Infection of the salivary glands
Streptococcus spp., Staphylococcus aureus
infections with non sporing anaerobes are commonly polymicrobial what does this mean?
Mixture of anaerobes and other organisms
Describe the clinical presentation of infections with non sporing anaerobes
- Often found in abscesses and wound infections
- May be associated with foul-smelling pus or
discharge
What are the general features of clostridium? (4)
- 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
Tetanus;
Type of infection?
Caused by?
Results from?
Where does the spores arise?
- Clostridal infection
- Caused by Clostridium tetani
- Usually follows from contamination of deep wound injury
- Spores in soil and general environment
Clinical presentation of tetanus? (4)
- Causes trismus (lockjaw)
- Dysphagia
- Muscle spasms
- Death by respiratory or cardiac failure
Botulism
Type of infection?
What causes?
How does it occur?
How does it work?
- 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
Clinical presentation of botulism (4)
- Vomiting
- Thirst
- Muscle paralysis
- Death by respiratory or cardiac failure
Gas gangrene
Type of infection?
Caused by?
Species involved?
- 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
What are Clostrodial toxins?
- Many Clostridium species produce potent exotoxins
- Some can be made into toxoids
- All are proteins and are antigenic
What is naglers reaction?
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.
