Exam 1; Periodontal Microbiology Flashcards by Courtney Kast

What is the great plate anomaly

everything you see doesn’t necessarily grow on a plate

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How many distinct oral species are there

700+ >60% have never been cultured

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This is an organized cooperating community of organisms with specific inter-bacterial and host-bacterial interactions

biofilm

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True or False Just as much (~24%) of bacteria is found in your body as found in your mouth

True

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This occurs when children are not exposed to a variety of bacteria, they develop autoantibodies to commensal bacteria

Atopy atopic dermatitis

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What occurs in the attachment phase of biofilm formation

planktonic bacteria adhere to acquired pellicle

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This type of “attacher” contains specific attachment structures (fimbrae, extracellular polymers, glycocalyx)

rapid attachers

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This type of “attacher” contains no specific mechanism of attachment

slow attachers

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How can bacterial characteristics change following attachment

synthesis of new outer membrane proteins active cellular growth

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This type of growth with biofilm formation is cell-to-cell recognition of genetically distinct cell types

co-aggregation

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What is co-aggreation mediated by

protein or glycoprotein receptors on one cell and carbohydrates on the other

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What physical characteristics are there involving co-aggregation

all cells are suspended “clumps” form, which then attach to the pellicle

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This type of growth with biofilm formation involves interactions between suspended and already adhering micro-organisms

co-adhesion

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What two things is co-adhesion influenced by

temperature (no co-adhesion >37°) lactose (high lactose, no co-adhesion)

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What three thins occur upon the maturation of the biofilm

increase in diversity replication and matrix formation ecological succession

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What are the primary colonizers

gram+ and gram- streptococci bind pellicle proteins from saliva (high #s) most are beneficial bacteria

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What are the secondary colonizers

gram- bridge species which bind other bacteria

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What is one of the main secondary colonizers

F. nucleatum (prolific coagregator)

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What are the tertiary colonizers

gram- pathogens like prophyromonas gingivalis

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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

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What is the nutrient source in supragingival plaque

dietary products in saliva

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What is the nutrient source in subginival plaque

periodontal tissues and bone

bacterial hydrolytic enzymes breakdown host macromolecules into peptides and amino acids

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What two things compose a biofilm

microcolonies (15-20%)

interbacterial matrix

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What are the three sources of the matrix

dead bacterial cells

saliva

gingival exudate

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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