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Oral Microbiology > Week 2 > Flashcards

Week 2 Flashcards

1
Q

Global burden of Caries

  • _________ people worldwide are affected by oral disease
  • Nearly _____ of the global population
  • Dental caries of the permanent teeth is the most _______ of all health conditions assessed
    • Incidence and prevalence persists in younger children _____ years of age since 1990
A

3.58 billion

half

prevalent

<10

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2
Q

Average saliva production in Adults and Kids

A

Child: 0.5-2L

Adult: 0.5-1.5L

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3
Q

Antimicrobial components of saliva (5)

A

lysozyme

lactoferrin

histatins

peroxidase

secretory IgA

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4
Q

lysozyme function to inhibit bacteria

A

Lysozyme digests the cell walls of Gram-positive bacteria by breaking the β(1-4) bond between N-acetylmuramic acid and N-acetylglucosamine (NAM-NAG) in peptidoglycan

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5
Q

lactoferrin funcction to inhibit bacteria

A

Lactoferrin inhibits bacterial growth by binding and sequestering Fe2+ ions, and in the apo (iron free) state can be toxic to bacteria and interfere with bacterial adhesion

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6
Q

histatins function to inhibit bacteria

A

cationic histidine rich proteins that kill Candida albicans and some bacteria.

can bind and infiltrate yeast which results in arrest of the cell cycle and the cells lose ATP by efflux

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7
Q

peroxidase function to inhibit bacteria

A

catalyzes the oxidation of thiocyanate (SCN−) to hypothiocyanite (OSCN−) by hydrogen peroxide.

Hypothiocyanite oxidizes SH groups in bacterial enzymes and inhibits bacterial metabolism.

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8
Q

secretory IgA function to inhibit bacteria

A

agglutination

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9
Q

2 major salivary agglutinins

A

Secretory IgA

Salivary Mucins

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10
Q

characteristics of secretory IgA

A

dimeric IgA

joining J chain

secretory component (facilitates trans-cellular transportation)

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11
Q

characteristics of salivary mucins

A

polypeptide backbone

serine, threonine, proline rich domains

oligosaccharide chains (glucose, galactose, fructose, mannose) w

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12
Q

what is agglutination?

A

the clumping of particles (antigens/antibody, mucin/surface protein)

Agglutinins are a major component of saliva and play an important role in mucosal immunity

Majority of agglutinated cells are swallowed and cleared from the oral cavity

Immobilized S-IgA/ mucins embedded in the acquired pellicle result in “fixed” agglutination on the tooth surface

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13
Q

difference between the salivary pellicle and aquired pellicle

A

when the salivary pellicle coats a hard surface (teeth), it is the aquired pellicle

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14
Q

what are the 3 virulence factors of Strep Mutans

A

Adhesion

Acidogenicity (makes acid)

Aciduricity (can survive in an acidic environment)

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15
Q

Major components of Adhesion:

________transferase (GTF)/ ________transferase (FTF)

  1. Convert ______ into _____ and _____ respectivel
  2. Facilitate _______ of Sm and other bacteria (Co-adhesion)
  3. Forms an _______________ that serves as energy storage
  4. _______ binding proteins (GBP)
A

Glucosyl, Fructosyl

sucrose, glucans, fructans

adhesion

external polysaccharide (EPS) matrix

glucan

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16
Q

Major components of acidogenicity (making acid)

S mutans uses ________ fermentation

  1. Converts _______ or _______ into ______ via glycolysis
  2. _________ can be shuttled in to various metabolic pathways in which organic acids are generated and ______ is produced for the cell
A

glycolytic

glucose, sucrose, pyruvate

pyruvate

ATP

17
Q

Major components of S mutans Aciduricity (can survive in acidic environment)

  1. how does it survive with external ph?
  2. how does it survive with internal pH?
A

external pH: modifies membrane composition which will decrease proton permeability

internal pH:

a. pump out the protons
b. F1F0 ATPase –> costs energy!

18
Q

Know the critical pH for Hydroxyapatite and Fluorapatite and the role of each in enamel equilibrium in the presence of acids and saliva

A

Hydroxyapetite is the building block for enamel (critical pH = 5.5)

Fluorapetite protects tooth from demineralization (critical pH = 4.5)

The ”Critical pH” for enamel remineralization/ demineralization is pH 5.5

19
Q

major target of fluoride

A

inhibits glycolysis

inhibits ATR mechanisms

a. arginine deiminase system (ADS)
b. ammonia synthesis

c. F0F1 ATPase (makes it non functional –> protons enter cell and destroy it)

20
Q

Silver can

  • disrupt __________ cell walls
  • _____ cell membranes
  • denature _______
  • bind ______

what is the zombie effect?

A

peptidoglycan

lyse

ribosomes

DNA

  • Bacteria that are killed by SDF further act as a carrier for silver ions
  • This can kill other living bacteria nearby in a process known as the “zombie effect.”
21
Q

Target of Xylitol and mechanism in Streptococcus mutans

A

xylitol directly inhibits DexA(enzyme that breaks down dextran, which is a class of branched glucans, plays a role in normal activity of glucosyltraansferases and glycosyltransferase efficieny)

inhbition of DexA c–> poor biofilm formation by S mutans

Reduced acid production

22
Q

Target of Epigallocatechin gallate (EGCG) and mechanism in Streptococcus mutans

A
  • Competes for binding on the salivary pellicle
  • Inhibit normal function of glucosyltransferases (gtf B,C,D)
  • Alter bacterial cell walls and/or cell membrane
23
Q

What are the four modes of transmission highlighted in the lecture recording? Provide an example of each

A
  1. Direct contact (blood or body fluids)
  2. Indirect contact (contaminated instrument or surface)
  3. Droplets or splatter (mucosa of the eyes, nose or mouth)
  4. Inhalation (airborne microorganisms)
24
Q

What is the chain of infection starting with the source?

A

Pathogenic organism –> reservoir of source –> mode of transmission –> portal of entry –> susceptible host

25
Q

What are the four blood-borne viruses highlighted in the lecture recording?

What has the highest risk of infection resulting from a needle stick from an infected patient?

A

Hepatitis B (HBV) * highest risk of infection after needle stick

Hepatitis C (HCV)

Hepatitis D associated with hepatitis B

HIV

26
Q

Is saliva considered to be potentially infectious?

A

Yes, saliva has always been considered potentially infectious (viruses can travel through salivary droplets)

27
Q

What is the most common mode of pathogen transmission in a healthcare setting?

A

hands/poor hand hygeine

28
Q

At what concentration of alcohol does an alcohol-based hand rub need to be in order to be considered an effective disinfectant?

A

60-95%

29
Q

What are the three reasons that gloves are warn?

Do you have to wash your hands if you wear gloves? Why or Why not?

A
  1. Minimize the risk of acquiring infections from patients
  2. Prevent microbial flora from being transmitted from health care personnel to patients
  3. Reduce contamination from one patient to another

****NOT A SUBSTITUTE FOR HANDWSHING, gloves can have small holes or tears that allow hands to be contaminated, or when taking off gloves hands can become contaminated

30
Q

define disinfection

A

kills of removes pathogenic organisms in a material or an object excluding bacterial spores so that they pose no threat of infection

31
Q

define szterilization

A

kills or removes all organisms and their spores in a material or an object

32
Q

what are 3 modes of sterilization?

A

heat (single strand breaks in DNA, protein denaturation and dissociate of membrane lipids)

radiation (break chemical bonds and ionize molecules)

chemicals (protein denaturation)

33
Q

2 types of disinfection

A

physical (filtration, UV, laser, ultrasound and sound ultrasonic)

chemical (alcohols, aldehydes, biguanides, phenol based compounds, halogen based, surfactant, oxidizing agents, heavy metals)

34
Q

What are the three classes of dental instruments? Provide an example of each

A
  1. Critical: used to penetrate soft tissue or bone, or enter into or contact the bloodstream or other normally sterile tissue (forceps, scalpels, bone chisels, scalers, and surgical burs), sterilized after each use (steam under pressure, dry heat or chemical vapor
  2. Semi-critical: contact mucous membranes of non intact skin (mirrors, reusable impression trays and amalgam condensers), sterilized after each use (sterilization or high level disinfection)
  3. Non-critical: contact only with intact skin (external components of x-ray heads, blood pressure cuffs and pulse ox), reprocessed between patients (intermediate or low level disinfection)
35
Q

What is the risk of having a biofilm established in water lines used for dental treatment?

Where do these bacteria often originate from? (2)

How might a dental office prevent biofilms in dental water lines?

A

Biofilms can serve as a reservoir, amplifying the numbers of free floating microorganisms in the water and released in aerosols

Originate from: water source (environmental organisms – harmless in immunocompetent people), back flow (from dental apparatus “suck back”, opportunistic respiratory pathogens and oral bacteria)

Prevention: independent reservoirs, chemical treatment, filtration, anti retraction valves, sterile water delivery systems, water testing, in office testing

36
Q

Why might a mouth rinse, such as chlorhexidine, be used prior to dental treatment?

A
  1. Reduces number of microorganisms in aerosols/splatter
  2. Decrease the number of microorganisms introduced into the blood stream
37
Q
A

Oral Microbiology (3 decks)

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