microbiology of oral and maxillofacial infections Flashcards
What is an absess?
Microorganism can grow in a confined space, they can stay localised to an area or break out and spread to other tissues.
Collection of pus composed of microorganisms and their products, inflammatory cells, tissue breakdown products, serum proteins, other organic material
what is the most common dental abscess?
Acute apical abscess
What are the characteristics of a peridontal abscess?
acute or chronic destructive process within the periodontium.
Collection of pus- this can connect with the oral cavity.
The periodontal pocket becomes blocked or seals such that a stagnant subgingival pool of microorganisms is formed
What are the microorganisms associated with periodontal abscess?
Anaerobic Gram-negative rods e.g. Porphyromonas and Prevotella species, fusobacteria
- Haemolytic and anaerobic streptococci
- Spirochaetes, Capnocytophaga and Actinomyces species
what is this?
Acute apical absess
what are the pathways which microorganisms may invade the pulp and periapicle tissues?
- From the apical foramen
- Via the periodontal ligament
- Via the bloodstream?
what is the microbiology of a dentoalveloar abscess?
Generally polymicrobial, ~3-8 species
• Strict anaerobes predominate
• Collect pus by needle aspiration
– A suitable transport medium must be used – Culture must be immediate
– Note on the request form when a sample is contaminated with saliva or plaque
what are the most commen microorganisms of a dentoalvelar abscess?
Facultative anaerobes (Streptococcus milleri group)
Obligate anaerobes
- Fusobacterium nucleatum
- Peptostreptococcus spp.
- Parvimonas micra
- Porphyromonas endodontalis
- Prevotella intermedia
What is known about the virulence factors of microorganisms of the dentoalveloar abscess?
Many are highly proteolytic e.g. Parvimonas and Porphyromonas species
Common bacterial associations e.g. Fusobacterium nucleatum and Parvimonas micra
Ability to invade tissue
Which microrganisms can invade the dentinal tubules and what does this look like?
Tubules can act as a barrier to penetration by some bacteria
Some facultative streptococci invade
Characteristic growth response as long chains of
cocci.
Can be replicated in vitro by added collagen to the medium.
Cell surface antigen 1/11 is needed for invasion
Which strand of strep antigen 1/11 binds collagen?
the ALA- rich repeat region binds collagen 1.
Can S.gordonii invade dentinal tubules?
Yes but only with a functional antigen 1/11 molecule
Can P.Gingivalis invade dentinal tubules?
P. gingivalis can only invade tubules with the assistance of S. gordonii expressing its own Antigen I/II
How does S. mutans Antigen I/II affect the invasions of other microganisms.
restores ability to invade to S. gordonii Ag I/II mutant, but does NOT allow P. gingivalis co-invasion
what is this?
Spread of a dentoalveolar abscess. Can spread through fascial planes.
What are the possible results of dental absceses?
What are these two images showing?
Actinomycosis.
What causes this?
osteomyelitis
