oral microbrio Flashcards
(35 cards)
1
Q
what are the 4 main features of the oral cavity
A
- teeth
- mucosal surfaces
- saliva
- gingival crevice fluid
2
Q
discuss the tooth as a habitat
A
- non shedding surface for colonisation
- have a number of surfaces
- not sterile
- bacteria accumulate in a biofilm (plaque)
- plaque is found in both health and disease
3
Q
what is plaque
A
a biofilm of microorganisms and it forms its own micro environment
4
Q
discuss the oral mucosal surfaces as a habitat
A
- stratified non-keratinized epithelia
- not sterile, has a population of commensal bacteria
- a barrier to deeper infection
- layers can be worn off and replaced
- houses immune cells in tissue
- if damaged can initiate inflammation
5
Q
discuss saliva in terms of oral microbiology
A
- washes the mouth and aids in physical removal of surface material
- buffering capacity vs. acids produced
- anti-microbial factors to control microorganisms
6
Q
discuss gingival crevice fluid in terms of microbiology
A
- GCF is serum components from the flow of serum-like fluid through the junction of the epithelium of the gingivae
- increased production of GCF during infection can lead to localised small rises in pH. this can shift types of bacteria that grow
- enzymes can contribute to tissue destruction (collagenase, elastase, trypsin)
- GCF also has antimicrobial properties (carries IgG)
7
Q
list physialc (non-specific) anti microbial factors of the oral cavity
A
- saliva flow
- mucins and agglutinin
- sloughing of surface epithelia cells
8
Q
discuss general antimicrobial (innate) factors of the oral cavity
A
- lysozyme = lysis of bacterial cell wall
- lactoferrins = sequestration of iron but also described to block some viral receptors and have some direct anti-bacterial and yeast activity
- sialoperoxidase = inhibits glycolysis
- antimicrobe peptides = most disrupt microbial membranes of either bacteria or yeast
**- PNMs **= patrolling of tissue and englufment and destruction of pathogens
9
Q
list more specific antimicrobial facotrs (adaptive) of the oral cavity
A
- serum immunoglobulins/antibodies = prevent adhesion and disrupt ability to colonise
- complement = binding to and prmoting phagocytosis of pathogens
10
Q
discuss dental plaque development
A
- initial deposition and colonisation of glycoproteins onto a clean surface
- forms microcolonies with polysaccharides, salivary proteins and glycoproteins via aerobic growth - pioneer species
- development of environment for anaerobic growth (more bacteria -> loss oxygen in environment)
- establishment of anaerobic bacteria and deposition (black pigmented anaerobes)
- mineral depositions
11
Q
explain how gingivitis and periodontal disease develop
A
- plaque develops changing the microenvironment
- anaerobes can establish
- mineral deposition can occur
- sub gingival deposits and growth will trigger inflammation
- bacteria also secrete enzymes weakening tissue causing more damage
12
Q
Where on the tooth does most bacterial growth occur?
A
gingical crevice
13
Q
Which bacteria are the first to colonise the dental biofilm in plaque formation?
A
Streptococci and actinomycetes
Have adherence properties
14
Q
discuss how an anaerobic microenvironment is developed and redox
A
- Oxygen has to diffuse into the plaque from the air.
- As O2 is used for bacterial respiration (it is reduced)
- This develops an anaerobic (reduced) ‘respiratory’ environment.
- A general rule of thumb is the more bacterial growth the more reduced / anaerobic the environment.
- Anaerobes required reduced/anaerobic conditions for their respiration.
- redox can be altered by more than just reduction of oxygen, but focus on bacteria reducing oxygen availiblity
- culture becomes more reduced unless more oxygen introduced
15
Q
explain how microbial nutrition gets more complex as plaque develops
A
- Bacteria in a biofilm contribute to other metabolism allowing complex plaque to develop.
- Increasing numbers of bacteria reduces the redox allowing anaerobes to establish.
- First colonisers are Streptococcus and Actinomyces sp.
- Late colonisers are black pigmented anaerobes.
- External factors can alter the risk of pathological plaque
- Remove or reduce growth – reduced risk
- Increase growth rate – increased risk
16
Q
discuss distribution of flora in the oral cavity
A
- plaque formation on teeth is not uniform
- depends on the degree of protection from oral removal of forces and gradients of biological factors from the host
17
Q
Which anaerobic bacteria are established onto developed plaque?
A
- Porphyromonas
gram -ve, anaerobic rods
18
Q
What changes in plaque development allows more bacteria to colonise?
A
Nutrition varies as flora changes
Change in plaque pH
19
Q
what factors affect plaque development
A
- age (acquisition continues with age)
- changes of microbiology
- diet change
- tooth eruption
- adhesion factors
20
Q
what is dental plaque made of
A
- bacteria
- proteins
- cations
- immunoglobulins
21
Q
what is calculus
A
- mineralised phosphates deposited around bacteria
- can occure subgingival or supragingival
- presence increases with age
- thise close contact with periodontal pathogens can lead to stimulation bone resorption
- once formed a lot of force is required to remove it
- dental products may include compounds to reduce mineralisation
phosphate containing ions:
- apatite (Ca and other ions including F, Cl and Br)
- brushite (Ca)
- whitlockite (Mg and Ca)
22
Q
what is dental caries (decay) and how does it occur
A
- non-specific due to increased acids causing local demineralization
- specific immune mediated where odontoclast over-activity occurs (eg. FORL)
23
Q
discuss the steps of FORL
A
- very specific feline dental issue
- chronic acumulation of microorganisms
- endothelial end epithelial production of cytokines
- initiation and stimulation of odontoclastic activity
- stem cells attracted to the gingival sulcus area by the cytokines
- insteada forming into macrophages the stem cells become clast cells
- clast cells dissolve mineralised tissue
- clast cells multinucleated giant dissolve the tooth tissue
24
Q
list microorganisms of the oral cavity
A
- streptococcus
- actinomyces
- neisseria
- fusobacterium
- porphyromonas
- candida
25
discuss oral streptococcus
- gram positive
- facultative anaerobes
- fastidious (requires enriched media)
- range of haemolytic activities
- found in all animals
- linked to a number of diseases (bacterial species and site dependent)
- can also cause opportunistic infection
-
26
discuss oral actinomyces
- gram positive
- slow growth rate
- colonise mucous membranes
- opportunistic pathogen particularly oral cavity infections
- colonies form branched networks of hyphae (easily confused with fungi)
- in rare cases these bacteria can cuase actinomycosis
- genera is common in the environment
27
discuss oral neisseria
- gram negative
- diplococci
- this genera colonize the mucosal surfaces of many species
- common isolate from oral cavity of dogs and other species
- requires oxygen but some prefer increased CO2
28
discuss oral porphyromonas
- gram negative
- anaerobic
- rod shaped bacteria
- produces pophyrin pigments
- not zoonotic
29
discuss link between cat bite abscesses and oral microbiology
- bacteria and cell debris from oral cavity (teeth/saliva) get trapped in wound
- defensive reaction of the tissue designed to prevent spread of infection occurs
- inflammatory response begins
- white blood cells arrive
- increased blood flow
- abscess formation = core of pus surrounded by granulation tissue
30
clinical signs of cat bite abscesses
- pyrexia
- results in inappetance and depression
- if spreads to deeper structures = bone/muscle/CNS signs
- abscess may not be apparent immediately
31
discuss microbiology of CBA
- creamy white
- anaerobic organisms are malodorous
- some bacteria possibly haemorrhagic
- routine culture is not done
- culture reserved for recurring abscesses
- **there will be a mix of gram types aerobes, facultative anaerobes and anaerobes in a CBA!**
- bites may also be a route for viral infection (FIV)
32
discuss mycological infections of the mouth
- yeasts are common part of oral flora and other mucous membranes
- out of 200 candidia species, only 2 are opportunist infections: albicans and tropicalis
- candidiasis is mainly a disease of keratinized epithelium
- infections observed in immunosuppressed or where there are other chronic oral diseases
- infections appear: white pseudomembranous covering greyish plaques with some ulceration
33
what is lumpy jaw
- caused by actinomyces bovis
- mucosal commensal invades tissue through breaks in the lining of the mouth. damage due to rough forage or sharp tooth damage
- pathology = tumor like swellings that slowly develope into immovable hard swellings on the upper and lower jaw of cattle, commonly at the central molar level.
- lumps consist of a honeycombed masses of thin bone filled with yellow pus
- advanced cases can develop and discharge small amounts of sticky pus containing gritty yellow granules
- most common treatments are iodine therapy or tetracyclines
34
what is wooden tongue
- caused by actinobacillus lingieresii (gram -ve facultative anaerobe)
- commensal of mucous membranes invades through breaks in the lining of the mouth due to abrasion by rough feed
- pathology: sudden onset with the tongue becoming hard, swollen and painful
- chronic pyograunulomatous inflammation of the soft tissue
- infections is limited in most cases to the soft tissue of the tongue and lymph nodes of the tongue
35
what is fusobacterium necrophorum
- gram negative obligate anaerobic
- pleomorphic bacterium
- found in the alimentary tract of animals and resp tract of cattle
- infections involve mucous membranes and underlying tissues of the oral cavity epithelium in calves and pigs, less common in goats
- to establish infections usually require injury that breaches an intact epidermal layer
- self limiting
- initially animals may show signs of not drinking
- involve several toxins: leucocidins, haemolysin and cytoplasmic toxin
