Anaerobic Bacteria Flashcards
What are obligate anaerobes
- Organisms unable to grow in presence of O2
- Require low reduction/oxidation potential (Eh)
What are facultative anaerobes and give examples
- Organisms which grow under aerobic or anaerobic conditions, e.g. E. coli, staphylococci, streptococci
What are obligate aerobes and give examples
- Organisms unable to grow in absence of O2, e.g. Pseudomonas, Neisseria
What are microaerophiles and give examples
- Organisms that require a small amount of O2 i.e. less than normal atmospheric level of 20% v/v, e.g. Campylobacter, Helicobacter
What are capnophiles and give examples
- Organisms that require 5 – 10% CO2 for growth, e.g. Brucella, Capnocytophaga
What are some methods for the cultivation of anaerobes
- Anaerobic Jars
- Anaerobic Cabinets
- Roll Tube Techniques
- Robertons cooked meat medium
How does the vacuum/replacement method for anaerobic jars work
Remove air with vacuum pump to replace the atmosphere with a gas mix including a palladium catalyst
How does the gas-generating sachets method for anaerobic jars work
‘Anaerogen’ sachets - O2 absorbed/CO2 produced/ no catalyst need/no water added
What air composition is used for vacuum anaerobic jars
80% N2, 10% H2, 10% CO2
How do anaerobic cabinets work for anaerobe cultivation
- Complete working chamber for anaerobes
- Contains atmosphere of 80% N2, 10% H2, 20% CO2
- Pass materials in and out via air lock
Name 3 types of clinically important anaerobes (gram positive genera)
- Cocci - peptostreptococcus
- Spore-forming rods - Clostridium
- Non-sporing rods - propionibacterium, eubacterium, actinomyces
Name 3 types of clinically important anaerobes (gram negative genera)
- Cocci - veillonella
- Rods and Filaments - Bacteriodes, Fusobacterium, Porphyromonas, Prevotella, Campylobacter
- Spirochaetes - spirochaeta, Treponema
What types of bacteria can be found in/cause dental alveolar/periapical abscesses
Oral streptococci and many oral anaerobes - obligate anaerobes are predominant here
What is osteomyelitis and what types of bacteria are often responsible
- Rare disease causing inflammation of the jaw bone cavity
- Anaerobic gram negative rods and streptococcus spp.
What is chronic marginal gingivitis and what types of bacteria are often involved
- Inflammation confined to the soft tissues of the gingiva as a result of dental plaque accumulation - no particular species of bacteria involved
What is Acute Ulcerative Gingivitis (AUG) and what bacterial species are often involved
- 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 periodontitis and what bacteria are often associated with it
- Gingival inflammation extending to the deeper tooth supporting structures with destruction of periodontal ligament and alveolar bone
- Porphyromonas gingival, prevotella intermedia, Actinobacillus actinomycetemcomitans, Capnocytophaga spp. etc
What is pericoronitis and what bacteria are often associated with it
- Inflammation of the soft tissues the surround the crown of a partially erupted tooth esp. mandibular third molars
- Oral anaerobes including P,. intermedia and fusobacterium nucleatum
What is Peri-implantitis and what bacteria are associated with it
- Inflammation around implant systems that replace missing teeth
- Oral anaerobes esp. P. gingivalis and P. intermedia
What is actinomycosis and what bacteria is associated with it
- Formation of a chronic granuloma with swelling
- In chronic cases multiple discharging sinuses observed
- Actinomyces Israelii
What is Sialadenitis and what bacteria are associated with it
- Infection of the salivary glands
- Streptococcus spp., staphylococcus aureus and gram negative anaerobes
Describe the general features of infection with non-spring anaerobes
- Occurs at various body sites
- Commonly polymicrobial
- Often found in abscesses and wound infection
- May be associated with foul-smelling pus or discharge
- Good anaerobic isolation techniques are needed for diagnosis
- Treatment may include surgical drainage and antibiotics
What type of bacteria are clostridium
- Gram positive large anaerobic rods
What does the production of endospores allow for clostridium bacteria
enable organisms to survive adverse conditions e.g. soil and on skin
Where are clostridium bacteria found
In human and animal intestine, soil, water, decaying animal and plant matter
Name a few important species of clostridium bacteria
C. difficile
C. botulinum
C. tetani
C, septicum
What bacterial species causes tetanus
Clostridium tetani
When does tetanus infection usually occur
Following from contamination of deep wound/ injury
What toxins does C.tetani produce
Tetanospasmin (neurotoxin)
Tetanolysin (haemolysin)
Describe the classic morphology of tetanus bacilli
Drumstick shape due to round terminal spores
What symptoms and complications are associated with tetanus
- Causes trismus (lockjaw) dysphagia
- Muscle spasms
- Death by respiratory or cardiac failure
What bacterial species causes Botulism
Clostridium Botulinum
What is Botulism often a result of
Ingestion of pre-formed toxin in food esp preserved meats and canned food
What types of extremely potent neurotoxins cause human botulism
A, B and E
What is the basic mechanism of C. Botulinum toxins
They block the release of acteylcholine from peripheral motor nerve endings
What are the symptoms and conplications associated with Botulism
- Vomiting
- Thirst
- Muscle paralysis
- Death by respiratory or cardiac failure
What is Gas Gangrene caused by
Histotoxic clostridia that produces a range of lethal and necrotising toxins:
- C. perfringens, C. novyi, C. septicum
What are the 3 stages of infection of gas gangrene
- Contamination
- Clostridial cellulitis
- Myonecrosis
What happens in gas gangrene
Gas is formed in tissues - crepitus
Often a polymicrobial infection of wounds
What are the symptoms of gas gangrene
- Fever
- Shock
- Delirium
- Coma
- Death
What treatment is there for gas gangrene
May require amputation but cane prevented by proper wound management
