Exam 2 High Yield

Which bacteria are most associated with ENAMEL caries?

S. mutans, S. sobrinus (mutans group)

Which bacteria are most associated with DENTINAL caries?

Lactobacilli

Which bacteria are most associated with ROOT caries?

Actinomyces viscosus (+ Lactobacilli, S. mutans)

A strep group that makes only ONE fermentation end product (mutans → lactic acid) is called?

Homo-fermentive

α-hemolytic oral strep that turn blood agar green are called?

Viridans strep

Which oral strep groups are α-hemolytic, and which is β-hemolytic?

α: mutans, oralis-mitis, salivarius; β: Milleri

A bacterium that PRODUCES acid as a metabolic byproduct is?

Acidogenic

A bacterium that TOLERATES and adapts to low pH is?

Aciduric

Name the aciduric mechanisms of S. mutans.

ATPase H+ pump; ↑ unsaturated fatty acids (↓ H+ permeability); arginine → NH3 + CO2; ↑ chaperones/proteases/DNA repair

Sucrose-derived glucose polymer, secreted as insoluble EPS to aid adhesion, is called?

Glucan

Water-soluble polysaccharide stored inside S. mutans and converted to acid when free sugar runs out is called?

IPS (intracellular polysaccharide)

What does Stephan's curve demonstrate?

Plaque pH drops below critical (5.5) after sugar intake, then recovers

Which bacterium is SYMBIOTIC with S. mutans (eats its lactic acid)?

Veillonella

Which bacterium is ANTAGONISTIC to S. mutans (makes peroxide)?

S. gordonii

In the Ecological Plaque Hypothesis of caries, what is the initial stressor?

Sugar (excess)

What factor is most closely associated with the caries 'window of infectivity' (6-18 months)?

Presence of teeth (eruption)

What maternal factors contribute to early childhood caries?

Mother/caregiver transmits S. mutans + poor dietary habits

What aspects of ancient diets excluded pit-and-fissure caries?

Low carbs/sugar; high fiber → attrition/abrasion outpaced caries

Is S. mutans today genetically the same as ancient S. mutans?

No — evolved (positive selection + new genes)

What genetic transfer mechanism drove S. mutans evolution?

Transformation (naturally competent)

What is the primary etiology of gingivitis?

Plaque (undisturbed accumulation)

Name host factors that increase periodontal disease risk.

Genetics, immune response, type 2 diabetes, smoking, poor oral hygiene, diet

When pioneer bacteria change the environment so later bacteria can colonize, this is called?

Bacterial/ecological succession

EARLY plaque: which bacteria are the pioneers?

Yellow/blue — Streptococci, Actinomyces (+ Veillonella)

EARLY plaque: what do pioneers use as nutrients?

Saliva, diet, carbohydrates

EARLY plaque: how do pioneers change the local environment?

Use up O2; provide co-aggregation binding sites

EARLY plaque: gingival condition?

Health — firm, no BOP, PD 0-3 mm, little plaque

MATURING plaque: which bacteria are the secondary colonizers?

Orange — F. nucleatum, Prevotella, Campylobacter

MATURING plaque: growth requirements of secondary colonizers?

Anaerobic; co-aggregate with Fusobacterium

MATURING plaque: how do secondary colonizers change the environment?

Initiate inflammation + bleeding → allow late colonizers

MATURE plaque: which bacteria are the late colonizers?

Red — P. gingivalis, T. forsythia, T. denticola (spirochetes)

MATURE plaque: growth requirements of late colonizers?

Blood/proteins (asaccharolytic); strict anaerobic

MATURE plaque: environmental changes?

Deeper pockets, ↑ GCF, ↑ pH + temp, ↓ redox, bleeding

Inflammation and destruction of the connective tissue and bone around the tooth is called?

Periodontal disease

Which condition: red, swollen gingiva; bleeding on probing; PD 2-5 mm; ↑ plaque?

Gingivitis

Which condition: red, swollen gingiva; calculus; bleeding on probing; PD >5 mm; tooth mobility?

Chronic periodontitis

Which condition: molar-incisor pattern; onset at puberty; bone loss despite little plaque?

Localized aggressive periodontitis (LAP / Grade C)

Bacterial etiology of chronic periodontitis?

Red complex — P. gingivalis, T. forsythia, T. denticola

Bacterial etiology of localized aggressive periodontitis (LAP)?

A.a. serotype b

Bacterial etiology of gingivitis (name the orange complex)?

F. nucleatum, P. intermedia, Campylobacter, E. nodatum, S. constellatus, Peptostreptococcus micros

What are membrane blebs and why do they matter?

G- outer-membrane vesicles releasing LPS (lipid A) → trigger inflammation

What virulence traits do all red complex bacteria share?

G-, anaerobic, late subgingival biofilm, asaccharolytic, proteolytic, toxic byproducts, immune-modulating, invasive

Why do anaerobic bacteria have a strong odor?

Protein → amino acid breakdown → volatile sulfur compounds (VSCs)

Natural History of Periodontal Disease (Sri Lanka): same heavy plaque, but no/moderate/rapid progression. What does this bell curve say about chronic periodontitis?

Complex (multifactorial) disease

Natural History of Periodontal Disease: biggest variable behind the bell curve?

Host factors

Which condition: punched-out papillae, gray pseudomembrane, pain, bleeding, fever, malaise, rapid progression?

ANUG (necrotizing gingivitis / trench mouth)

Bacterial etiology of ANUG?

P. intermedia, F. nucleatum, spirochetes (Treponemes)

Host factors for ANUG?

Stress, malnutrition, immunosuppression, drug use, poor oral hygiene

Host factors for LAP?

Neutrophil dysfunction (chemotaxis, oxidative burst); strong genetics

Virulence factors of A.a. serotype b (CLIFF)?

Cytolethal distending toxin, Leukotoxin, Invasion, Fc-binding protein, Fimbriae

Which A.a. toxin kills PMNs?

Leukotoxin

Which A.a. toxin enters the nucleus and degrades DNA → pocket formation?

Cytolethal distending toxin

By what routes can bacteria enter the pulp?

Enamel flaws (caries, fracture, microleakage); subgingival via tubules + lateral/accessory canals; anachoresis

Bacteria in the bloodstream seeding the pulp is called?

Anachoresis

A deep periodontal pocket communicating with the pulp via a lateral canal is called?

Perio-endo lesion

A drainage path for pus from an abscess/periapical infection is called?

Sinus tract

Why can enteric organisms be found in the mouth?

Opportunistic colonizers of infected root canals

An infection arising from the patient's own normal flora is called?

Endogenous infection

An infection caused by many microbes is called?

Polymicrobial

Main bacterium of secondary endodontic infections (failed root canals)?

Enterococcus faecalis

Bacterial etiology of oral abscesses?

Orange + red complex (G- anaerobes); polymicrobial

Bacterial etiology (and treatment) of Ludwig's angina?

Endogenous oral flora (90% dental source); Tx amoxicillin/metronidazole

A painless oral abscess extruding pus with sulfur granules is most likely?

Actinomycosis (A. israelii)

Two major targets for antifungal drugs in Candida?

Cell wall + cell membrane

Which antifungal class INHIBITS ergosterol synthesis?

Azoles

Which antifungals BIND ergosterol in the fungal membrane?

Polyenes (nystatin) + amphotericin B

Which antifungal class inhibits synthesis of the cell wall component β-(1,3)-D-glucan?

Echinocandins

Clotrimazole, miconazole, and fluconazole belong to which antifungal class?

Azoles

Which azole can also be given systemically by tablet?

Fluconazole

Nystatin belongs to which antifungal class?

Polyenes

Which polyene is applied topically as an ointment or oral suspension?

Nystatin

Which antifungal binds ergosterol, is given IV for systemic infections, is poorly tolerated ('ampho-terrible'), and can be a lozenge for topical use?

Amphotericin B

Which echinocandin is given once daily by slow IV infusion for severe Candida/Aspergillus infections?

Caspofungin

C. albicans can exist as both yeast and hyphae, which makes it?

Dimorphic

Which C. albicans form is unicellular and reproduces by asexual budding?

Yeast

Which C. albicans form is spore-forming?

Pseudohyphae

Which C. albicans form (germ tubes) reproduces sexually?

True hyphae

Why are hyphal forms of C. albicans more pathogenic?

↑ proteases + lipases → tissue invasion

Is C. albicans a frank pathogen, opportunistic pathogen, or commensal?

Commensal → opportunistic pathogen

Which candidiasis: creamy-white plaques that wipe off, leaving red areas; yeast overgrowth?

Pseudomembranous candidiasis (thrush)

Host factors for thrush?

Newborns (immature immunity/flora); older adults (poor nutrition, steroid inhaler, systemic disease)

Which candidiasis: most common form; red, painful lesions; invasive hyphae; tongue depapillation?

Erythematous candidiasis

Host factors for erythematous candidiasis?

Dentures (chronic atrophic); antibiotics, steroids, HIV (acute atrophic)

Which candidiasis: white patches that can't be wiped off; risk of becoming cancerous?

Chronic hyperplastic candidiasis (candidal leukoplakia)

Host factors for chronic hyperplastic candidiasis?

Middle-aged male smokers

Which candidiasis: inflamed corners of the mouth; trapped saliva; ± S. aureus?

Angular cheilitis

Host factors for angular cheilitis?

Smokers, elderly/dysphagia, immunosuppressed, other candidiasis

Which salivary factors specifically protect against Candida?

Histatins (Hst5) + defensins

Which oral bacterium has gliding motility?

Capnocytophaga

Which oral bacterium has an internal 'star' in its colonies?

A.a. serotype a

Which oral bacterium is a spirochete?

Treponema denticola

Which bacterium is associated with S. mutans in caries?

Veillonella

Which oral bacteria are Gram-positive branching rods?

Actinomyces

Which oral bacteria are capnophilic?

Capnocytophaga, A.a.

Which oral bacteria are black-pigmented on blood agar?

P. gingivalis, many Prevotella

Which is the 'bridge' bacterium?

Fusobacterium nucleatum

Clenched fist injury after punching someone in the mouth — likely bacterium?

Eikenella corrodens

P. gingivalis vs Prevotella (both black-pigmented): which is red complex?

P. gingivalis (Prevotella = orange)

Veillonella vs Peptostreptococcus micros: which is the Gram- coccus?

Veillonella

A. viscosus vs A. israelii: which causes actinomycosis?

A. israelii (viscosus = root caries)