1/16 Nguyen Microbiology of Periodontal Disease Flashcards
Define periodontitis
Bacterial infection of supporting tissue around teeth
Periodontitis is a _____ disease
Chronic inflammatory
With periodontitis, local environment changes correlates with a shift in _____. There is a decrease in _____ and an increase in ______
bacterial population; Gram positive bacteria; oral treponemes and gram negative bacteria
Development of gingivitis follows what pattern?
- Biofilm formation
- Plaque development
- gingivitis
What happens after cessation of dental hygiene for 7 days?
Biofilm on tooth surfaces, leads to plaque and gingivitis
At first, biofilm formation is started by ____ bacteria. After 48 hours, there is a ____ in Streptococci. After 10 days, the bacteria found are?
70% streptococci; decrease; highly diverse, orange and red complex bacteria
Plaque hypothesis: non-specific plaque
All plaque is bad, large amount produces periodontitis
Plaque hypothesis: specific plaque
Specific organisms cause periodontitis
Plaque hypothesis: ecological plaque
- Stressors induce changes towards diseases
- shift balance towards disease
Ecological plaque hypothesis - examples of stressors
- physiologic
- environmental
- chemical
Describe the pathway of gingivitis onset (ecological plaque hypothesis)
- Increased plaque with stress produces increased inflammation
- Environmental change causes high GCF flow, inc. pH, low Eh
- Ecological shift causes increase in Gram negative flora
Periodontal disease main risk factor
Smoking (greatest independent factor, 3-8x risk)
Example of a local factor that attributes towards periodontal disease
Appliances (brackets)
Good oral health has what kind of bacterial population?
- microbial diversity
- more commensal/facultative organisms
- fewer gram +/- rods
In periodontitis, there is a marked shift towards:
Gram-negative anaerobes (bacilli)
Anaerobes that live in deep crevices
Where is gingivitis located around the tooth/gums?
- Small amount that ends near CEJ
- less recession, smaller
Where is periodontitis located around the tooth/gums?
- more plaque, deeper, can extend to the root
- more recession
Gram positive streptococci are considered _____ colonizers
Pioneer and early colonizers
Pioneer organisms attach to:
Tooth surface covered with acquired pellicle
____ link pioneer organisms to late colonizers using adhesion/receptor mechanisms
Early colonizers
Gram-negative bacteria are considered ____ colonizers
Late/secondary and tertiary
Which bacteria are highly associated with periodontitis?
- Aggregatibacter actinomycetemcomitans
- Porphyromonas gingivalis
- Tannerella forsythia
____ is associated with aggressive periodontitis
Aggregatibacter actinomycetemcomitans
_____ is associated with chronic periodontitis
- Porphyromonas gingivalis
- Tannerella forsythia
Oral ecologic succession: what complexes are the first to colonize?
Yellow, green, purple complexes
(gram-positive early tooth colonizers)
Oral ecologic succession: what complexes are second to colonize?
Green (some), orange, red
(Gram-negatives)
Red complex organisms are ____ implicated in periodontal disease
Strongly
There is _____ associated with red complex organisms
biochemical interdependence
form red-red complexes together
What are the red complex organisms?
- Porphyromonas gingivalis
- Tannerella forsythia
- Treponema denticola
P. gingivalis classification
- gram-negative rod
- non-motile
- anaerobic
P. gingivalis virulence factors
- fimbriae (adhesion)
- LPS (endotoxin, inflammation)
- Capsular polysaccharide to evade host defenses
- Proteases: gingipains (PMN inhibition, tissue damage)
What is the function of P. gingivalis gingipains?
- PMN inhibition
- tissue damage
Mode of action of Porphyromonas gingivalis
- P. gingivalis infection in periodontal pocket
- hijacking of local complement system
- amplification of local antimicrobial activity
- profound change in local microbiota composition
- chronic inflammation
P. gingivalis gingipains activate ____ in periodontal tissues
PAR2
Activation of PAR2 by gingipains induces the production of _____ in periodontal tissues. This leads to:
Pro-inflammatory cytokine mediators; periodontal breakdown
Pro-inflammatory cytokine mediators associated with PAR2 activation
IL-1 beta, IL-2, IL-6, TNF-alpha, MMPs
Periodontal breakdown from gingipains involves:
- degradation of collagen and fibronectin, complement, PMN receptors
- activate fibrinolytic system
- tissue destruction
P. gingivalis gingipains are strongly expressed after:
Incubation with T. denticola (spirochete)
Gingipains further alter ______ of the periodontal pocket and may lead to _____
Microbial composition; chronic inflammation
T. denticola classification
- Gram-negative spirochete
- anaerobic
T. denticola is motile due to presence of:
Periplasmic flagella
_____ has resistance to human beta-defensins
T. denticola
What do human beta-defensins do?
- form pores within bacterial cell membrane
- causes permeation and leakage of intracellular contents
Tannerella forsythia classification
- Gram-negative
- fusiform
- anaerobic
Main virulence factor of T. forsythia
Glycosidases
Glycosidases function
Degrade complex carbohydrates (proteoglycan) to expose binding sites
Orange complex organisms are _____ risk
Moderate
What are the orange complex organisms?
- Prevotella intermedia
- Prevotella melaninogenica
- Fusobacterium nucleatum
- Campylobacter rectus
- Eubacterium nodatum
- Peptostreptococcus sp.
P. intermedia classification
- Gram-negative
- Anaerobic
- coccobacilli
P. intermedia produces ____ which converts _____ to black pigment
Hemolysin; Hemoglobin
F. nucleatum classification
- Gram-negative
- anaerobic
- fusiform rod
F. nucleatum is a ____ because it adheres to a wide range of organisms
Corn cob
____ is a bridge species between early and late colonizers
F. nucleatum
F. nucleatum is a part of the normal oral flora, and there is a huge increase in _____
Acute necrotizing ulcerative gingivitis
Campylobacter rectus classification
- Gram-negative
- facultative anaerobic
- motile rods (curved, S-shaped)
Campylobacter rectus virulence factors
- Flagella (motility)
- cytotoxins
- slime layer
Slime layer in C. rectus provides:
Adhesion
Cytotoxins in C. rectus function
Tissue damage
Eubacterium - orange complex species
- E. yurii
- E. nodatum
E. nodatum/E. yurii classification
- Gram-positive bacilli
- anaerobe
Eubacterium sp. facilitate:
Corn cob formation (facilitate inter-species interaction)
Eubacterium virulence factors
- Adhesion (implants, brackets)
- Butyric acid (inhibits wound healing)
- Can cause pelvic inflammatory disease
Peptostreptococcus sp. classification
- Gram-positive streptococcus
- Obligate anaerobe
Peptostreptococcus virulence factors
- can produce capsular material
- can facilitate co-aggregation
- acid, protease production
- can cause fatal endocarditis
Green complex organisms are _____ risk
Moderate
Green complex organisms
- Eikenella corrodens
- Captocytophagia species
Eikenella corrodens classification
- gram-negative pleiomorphic rod
- facultative anaerobe
Eikenella corrodens is mainly a ____ of the oral cavity but can also cause disease
Commensal
____ is associated with braces and poor oral hygiene
Eikenella corrodens
Eikenella corrodens main virulence factor
type 2 autoinducer, quorum sensing molecules
Captocytophagia sp. classification
- Gram-negative bacilli
- facultative anaerobe
- opportunistic pathogen
Captocytophagia virulence factors
- resistance to 3rd gen. cephalosporins
- CfxA
- facilitates co-aggregation, F. nucleatum
- Endocarditis
What is CfxA?
Broad spectrum beta lactamase
Aggregatibacter actinomycetemcomitans (AA) is a _____ complex pathogen
Purple (but technically Green)
Aggregatibacter actinomycetemcomitans (AA) classification
- Gram-negative coccobacilli
Aggregatibacter actinomycetemcomitans (AA) is a _____ pathogen found in _____
High risk; localized aggressive periodontitis
Aggressive Early Onset Periodontitis is ____ in children and young adults
Uncommon
Aggressive Early Onset Periodontitis is a result of:
Highly virulent bacteria and/or highly susceptible subject
Aggressive Early Onset Periodontitis is caused by what bacteria?
Aggregatibacter actinomycetemcomitans (AA)
Aggregatibacter actinomycetemcomitans (AA) virulence factors
- Leukotoxin A
- chemotactic factor
- immunosuppressive factor
- ompA (Fc binding protein)
What does leukotoxin A do?
- Kills PMN (Leukocytes, CD18) by forming pores
- depletes neutrophils
- damaged PMN release lysosomes to further damage periodontal tissues
Overall, leukotoxin A causes:
- periodontal destruction
- impaired defense
- microbial nutrition
What is acute necrotizing ulcerative gingivitis (ANUG)?
Severe form of periodontitis in an impaired host
Acute necrotizing ulcerative gingivitis (ANUG) symptoms
Severe necrosis of free gingival margins, crest of gingiva, interdental papilla
Acute necrotizing ulcerative gingivitis (ANUG) involves ____ infections, including many _____
Mixed anaerobic; different anaerobic microbes