Exam 1; Periodontal Microbiology Flashcards
What is the great plate anomaly
everything you see doesn’t necessarily grow on a plate
How many distinct oral species are there
700+ >60% have never been cultured
This is an organized cooperating community of organisms with specific inter-bacterial and host-bacterial interactions
biofilm
True or False Just as much (~24%) of bacteria is found in your body as found in your mouth
True
This occurs when children are not exposed to a variety of bacteria, they develop autoantibodies to commensal bacteria
Atopy atopic dermatitis
What occurs in the attachment phase of biofilm formation
planktonic bacteria adhere to acquired pellicle
This type of “attacher” contains specific attachment structures (fimbrae, extracellular polymers, glycocalyx)
rapid attachers
This type of “attacher” contains no specific mechanism of attachment
slow attachers
How can bacterial characteristics change following attachment
synthesis of new outer membrane proteins active cellular growth
This type of growth with biofilm formation is cell-to-cell recognition of genetically distinct cell types
co-aggregation
What is co-aggreation mediated by
protein or glycoprotein receptors on one cell and carbohydrates on the other
What physical characteristics are there involving co-aggregation
all cells are suspended “clumps” form, which then attach to the pellicle
This type of growth with biofilm formation involves interactions between suspended and already adhering micro-organisms
co-adhesion
What two things is co-adhesion influenced by
temperature (no co-adhesion >37°) lactose (high lactose, no co-adhesion)
What three thins occur upon the maturation of the biofilm
increase in diversity replication and matrix formation ecological succession
What are the primary colonizers
gram+ and gram- streptococci bind pellicle proteins from saliva (high #s) most are beneficial bacteria
What are the secondary colonizers
gram- bridge species which bind other bacteria
What is one of the main secondary colonizers
F. nucleatum (prolific coagregator)
What are the tertiary colonizers
gram- pathogens like prophyromonas gingivalis
What four things occur upon increasing the thickness of a biofilm
difficulty in diffusion in and out of the biofilm
an oxygen gradient develops
completely anaerobic conditions ermege in the deeper layers
reverse gradients of fermentation products develop as a result of bacterial metabolism
What is the nutrient source in supragingival plaque
dietary products in saliva
What is the nutrient source in subginival plaque
periodontal tissues and bone
bacterial hydrolytic enzymes breakdown host macromolecules into peptides and amino acids
What two things compose a biofilm
microcolonies (15-20%)
interbacterial matrix
What are the three sources of the matrix
dead bacterial cells
saliva
gingival exudate
This is the backone of the biofilm
exopolysaccharides
What four characteristics compose the lower layer of the biofilm
dense layer of microbes
polysaccharide matrix
tighly bound together
steep diffusion gradients (stuff cannot penetrate)
What are two characteristics of the loose layer
irregular in appearance
extends into surrounding medium
What are three characteristics of the fluid layer
stationary sublayer
fluid layer in motion
nourishes the biofilm by molecular diffusion
The shape of micro-colonies depends on what
shear force
What shape of microcolonies as a low shear force
tower or mushrooms (interdental surface)
What shape of microcolonies has a high shear force
elongated colonies capable of oscillation (like kelp)
What three things compose the interbacterial matrix
gram positive matrix - very fibrilar
gram negative matrix - very regular
interbacterial carbohydrates
What gives the gram positive matrix its “fibrillarity”
dextrans and levans
What are three characteristics of the gram negative matrix
tri-laminar vesicles
filled with endotoxins and proteolytic enzymes
probably involved in adherence
What is the energy source of interbacterial carbohydrates
dextrans and fructose
What forms the primary attachemnt for subgingival plaque
cuticle
What are two differences between supra and sub gingival plaque
no inter-bacterial matrix
more spirochetes and flagellated bacteria
Bacterial collaboration is necessary for what
succession (of biofilm growth)
This species of bacteria is facultative, but uses all the O2 when available
Strep. cristatus
This bacterial species is a robust anaerobe and binding to strep imporoves survival when O2 is present
fusobacterium nucleatum
This bacterial species is microaerophilic, obligate anaerobe of which coaggregation is essental to survival when O2 is present
prophyromonas gingivalis
What were the results of the tissue culture experiment of which involved F. nucleatum and S. cristatus
F. N. invaded epithelial cells
S.C. does not invade epithelial cells
after coaggregation, S.C. is carried inside cells via F.N
What are the two characteristics of the defense benefit of a biofilm
presence of concentrated bacterial enzymes
interbacterial matrix
What are the four characteristics of a biofilm regarding protection from external changes
diffusion minimal in interior regions
antibiotic and antimicrobial resistance
protection from friction and shearing forces
attachment
What are the five characeristsis of a biofilm ragarding transfer of information and genetic material
signaling (quorum sensing)
conjugation
transformation
plasmid transfer
transposon transfer
This is the regulation of expression of specific genes through accumulation of signaling compounds that mediate intercellular communication
quorum sensing
Auto-inducer (AI) 1 or 2 turns on when
in response to cell density
Which bacterial produce AI in high and low levels
commensal bacteria = AI in low levls
pathogenic bacteria = AI in high levels
AI-2 may determine what
the switch from commensal to pathogenic community
biofilm bacteria are how many more times antiobiotic resistant than planktonic
1000-1500
What three things are characteristic of a biofilm growing more slowly
antiobiotics depend upon cell turnover for efficacy (targets replication mechanims)
slow-growers express non-specific defnese mechanisms
slow-growers make more exo-polymers
These retard diffusion
exo-polymers
Ion-exchange mechanism prevents what
highly charges molecules from reaching deeper zones
extracellular enzymes (beta-lactamases, formaldehyde, dehydrogenase, formaldehyde lyase) inactivae what
antibiotics
Biofilm bacteria express different genes, how?
gene transfer
phenotypic expression of biofilm exsistance
Why dont oral pathogens not fit the classic concept of a pathogen
normally present throughout life
damage requires presence in large numbers
What three things are characteristic of the ecological concept of oral pathogens
ecological shifts lead to change in proportions
balance shifts in favor of pathogens/disease
periodontal disease is an example of “ecological catastrophe”
What three clinical things influence of the structure of the biofilm
changed tooth-brushing paradigms
hard to reach interproximal and fissures
non-contact brushing can remove towers and mushrooms by force (power toothbrushes)
What are two targets for biofilm therapy
AI-2
vaccines that target common resistance genes
This can translocate pathogens from pockets to healthy sites
periodontal probe
These can translocate to neighboring teeth
drug-resistant strains
Teeth act as reservoirs for the colonization of what
implants
What are the four steps for a “one-stage, full-mouth disinfection”
full mouth scaling and root planing within 25 hours
subgingival irrigation with 1% chlorohexedine
tonge brushing
oral antimicrobial rinse
What are two characteristsi of peri-implant plaque
plaque can from on implant abutments
implants that fail have a microbial composition similar to periodontal disease
What is the non-specific plaque hypothetsis
plaque control is important for periodontal treatment
all plaque is considered bad
any accumulation of micro-organiss at or below the gingival margin causes inflammation
What is the specific plaque hypothesis
specific organisms in dental plaque are the etiological agents
microbial composition of disease sites different from healthy sites
local debridement and systemic antibiotics could control LAP (localized aggressive periodontitis)
What are the three prerequisites for disease initiation and progression
virulent periodontal pathogen
the local environment
host susceptibility
What three properties must the virulent periodontal pathogen have
strains (not the species) are imporntant
must express virulence factors
must be in the right location in the site (adjacent to epithelium, in the pocket, etc.)
What two properties of colonization by beneficial species influence the local environment
dilute levels of pathogens
inhibit pathogens
What two properties involving the effect of local “regulon” (subgingival enviroment) influence the local enviroment
iron can increase out membrane protein expression in P. gingivalis
S. cristatus can inhibit fimA expression
What three things can influence host susceptibility
HIV
diabetes
smoking
What are the two types of adhesins on bacterial that bind it to host receptors
Type I or IV collagen, sialic acid, galactosyl residues
fimbrae outer membrane proteins
Veillonella uses this made by streptococci as nutrient utlization of pathogenic mechanisms
lactate
Campylobacter uses this made by Selenomonas as nutrient utlization of pathogenic mechanisms
fomate
Porphyromonas uses this from blood in the sulcus as nutrient utlization of pathogenic mechanisms
hemin
What are the two competitive inhibition pathogenic mechanisms
bacteriocins
hydrogen peroxide production (S. sanguis inhibits AA)
What are the four colonization pathogenic mechanisms
adhesions on bacteria bind to host receptors
coaggregation
nutrient utilization
competitive inhibition
What are the three pathogenic mechanisms for overcoming host defenses
desquamation of epithelium
antibody prevent binding
phagocytic cells
What are two mechanisms behind desquamation of epithelium
invade epithelium
bind to underlying cells
What are two mechansisms involving antibody prevent binding
IgG and IgA proteases (break down of IgG and IgA)
mimic host antigens
What are two mechanisms behind phagocytic cell pathogen mechanisms
leukotoxin
non-lethal suppression of immune cells
What are three characteristics of periodontal pathogens
complex microbial profile
sveral uncultivated species
microbial complexes
The world workshop in 1996 designated what three pathogens
P. gingivalis
A. actinomycetemocomitans
T. forsythia
Which three bacteria is there strong evidence they are pathogenic
Actinobacillus actinomycetemcomitans (A.A.)
Porphyromonas gingivalis (P. gingivalis)
Bacteriodes forsythus (B. forsythus)
Which 7 bacteria is there moderate evidence of pathogenicity
C. rectus
E. nodatum
F. nucleatum
P. intermedia/nigrescens
P. micros
S. intermedius-complex
T. denticola
Which four bacteria is there initial evidence of pathogenicity
E. corrodens
enteric rods
pseudomonas
selenomonas
Which bacteria is;
non-motile
gram -
sacchrolytic
capnophilic
round-ended rod
characteristic star-shaped colonies
Actinobacillus actinomycetemocomitans
AA
