Micro Flashcards
4 types microbes in canal? most common?
bacteria (most), fungi, viral, prion
What 2 findings ended focal infection era
- blayney - endo infection can be treated with good tx
2. grossman - pulpless treated tooth can have healthy PDL
Culturing established most infected pulps had what bacteria?
73-90% anaerobes
Pyrosequencing est how many species bacteria in infected pulps? how many possibl?
40, 400+
Top 3 root canal bacteria
F nucleatum
Strep sp
Bacteroides
bacteria vs symptomatic teeth?
more symptomatic = more bacterial diversity
Interactive and associative characteristics of canal infections
interactive - selection for anaerobic
Associative - certain bacteria associate with certain others
Pathogenesis depends on 3 factors for infection
- density of bacteria
- virulence factors
- host resistance
4 main ecological factors of canal
Low Oxygen Tension
Low Reduction-Oxidation Potential
Nutrient-Rich
Byproducts
Fabricius found what about # anaerobes over time in canal?
increased over time;
by 1080 days, 98% are obligate anaerobes
8 virulence factors
Fimbriae Capsules Extracellular vesicles Enzymes Metabolic byproducts LTA LPS (endotoxin) Synergism
Effects of: Collagenase: Chondroitin Sulfatase: Hyaluronidase: Kinases: Gelatinase: Proteases: Coagulase: Hemolysins: Leukocidin: DNA-ase:
Collagenase: Destroys collagen Chondroitin Sulfatase: Digests ground substances Hyaluronidase: Digests ground substances Kinases: Fibrinolysin Gelatinase: Proteolytic Proteases: Proteolytic Coagulase: Activates fibrin clots Hemolysins: Destroys RBCs Leukocidin: Destroys WBCs DNA-ase: Destroys nucleic acids
ex of metabolic byproducts
sulfur granules produced by israeli
LTA is what, stimulates what
Lipoteichoic acid, part of gram+ wall, stimualtes specific immune response
LPS is what
endotoxin/lipopolysaccharides
from gram negative
LPS can cause what
fever, bone resorption, vasomotor shock, and T-cell stimulation
Speed of LPS spread vs bacteria?
can progress through canal/tubules faster than bacteria
3 patterns of synergism
planktonic, aggregates, Biofilms
Planktonic synergism most common in what kind of infections
acute purulent
81% infected RC samples have what kind of synergism
co-aggregation
what is a biofilm
Polybacterial communities embedded in a polysaccharide matrix and attached to a surface
communication methods (2) within biofilms
quorum sensing, share genes
5 ways biofilms resist
Diffusion gradient – slow antimicrobial penetration requires 100-1000x [abx|
Many bacteria are in the stationary phase
Neutralizing reactions deplete antimicrobials
Persister cells – spore like/dormant
break down Ca++ from dentin and use as walls
Viruses indirectly increase virulence how
bacteriophages inject virulence factor DNA into bacteria
types of viruses directly implicated in RC infection
CMV/EBV
Why are CMV/EBV implicated in symptomatic infections?
increase proinflammatory cytokines
Bleach irrigant composition?
SPectrum?
Unique bc?
bad bc?
5.25% NaOCl
Broad spectrum
Only irrigant that dissolves organic material
Toxic if extruded from canal, must continuously replenish
Chlorhexidine concentration?
Kills what?
effect on tissue?
Caution when used with what?
2%
Kills bacteria
No tissue dissolution
Not toxic unless mixed with bleach, forms parachloroanaline
EDTA concentration?
What kind of agent/action?
Action vs microbes?
Used in conjuction with what?
17%
chelating - opens tubules and enhances penetration
No antimicrobial activity
Conjunction with bleach
MTAD is what?
Mixture of Tetracycline, citric Acid, and Detergent (Tween 80)
Does MTAD contain bleach?
Affect on tissue?
Adjunct with what? Better than other adjunct?
No
No tissue dissolution
Bleach, but not better than EDTA
Majority of endo infections require abx?
NO
Indications of abx in endo (8)
Fever
Immunocompromised
Lymphadenopathy
Malaise
Cellulitis
Osteomyelitis
Swelling
Trismus
FILM COST
Abx of choice?
Abx for PCN allergic?
PenVK
Clinda
Considerations for use of Augmentin/Amox?
For Metronidazole?
Aug/Amox - broad spectrum and $$$, use only for immunocompromised
Metro - Only affective against obligate anaerobes, cant use alone.
Rank abx in decreasing susceptibility?
Augmentin Clinda Amox PenVK Metro
Can abx cure endo infections? What is their function?
No, only cured by removing infected tissue; they assist in restoring proper balance
Two mechanisms of resistance transfer?
vertical (daughter) horizontal (to other strains not even exposed)
Contraindications of abx in endo? (3)
What could these be?
Pain without signs of infection (Symptomatic irreversible pulpitis, Acute periradicular perio)
Asymptomatic teeth with necrotic pulps (asymptomatic apical perio)
Teeth with sinus tract (chronic apical abcess)
PenVK Major advantage? Spectrum? Drug of choice for? Major disadvantage? Dose?
Major advantage? Low cost, low toxicity
Spectrum? High effectiveness against anaerobic in root
Drug of choice for? periradicular abcesses
Major disadvantage? can cause allergy in 10%
Dose? 1g loading, 500mg q6h for 5-7d
Amox Major advantage? Spectrum? Drug of choice for? Major disadvantage? Dose? Relationsihp to Augmentin? Dose?
Major advantage? More rapid absorption, longer halflife, higher serum levels
Spectrum? extended (vs PenVK)
Drug of choice for? medically compromised, serious odontogenic infections
Major disadvantage? Resistance
Dose? 1g loading, 500mg q8h for 5-7days
Augmentin is Amox + Clavulanate for beta-lactamase bacteria
Dose: 875/125mg q12h for 7d
Clinda Major advantage? Spectrum? Drug of choice for? Major disadvantage? Dose?
Major advantage? high conc in bone
Spectrum? gram positive, anaerobes
Drug of choice for? pen allergic pt
Major disadvantage? can cause pseudomembranous colitis
Dose? 600mg loading, 300mg q8h for 5-7days
Metronidazole Major advantage? Spectrum? Drug of choice for? Major disadvantage? Dose?
Major advantage? used in combination with penicillin if symptoms worsen/resistance
Spectrum? narrow; anaerobes only
Drug of choice for? resistant to pcn
Major disadvantage? many bacteria resistant
Dose? 1g loading, 500mg q6h for 5-7d
Erythromycin spectrum?
none vs anaerobes
Clarithromycin aka? Clarith and Azith Spectrum? Major disadvantage? Dose?
Spectrum aerobic coverage but not ideal
food/metal slow absorption
500mg loading, 250mg q12h for 5-7d
Azith same but qd
Cephalosporins first vs second gen?
How many % cross react with pen?
1st - no efficacy
2nd - better vs aerobes
15% cross react
Tetracycline/Doxycycline good b/c but bad bc?
very broad spectrum but may produce resistance
Quinolones aka?
Spectrum?
Good for?
Ciprofloxacin
Bad against anaerobes in RC infections
Persistent infections with sensitivity testing
Abx treat ____ not ____
treat infection not pain