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DENT 410 - IPA > Microbiology I - 20Sept2013 > Flashcards

Microbiology I - 20Sept2013 Flashcards

1
Q

Infection transmission during dental procedures is dependent on 4 factors:

A

A. Source of infection
B. Means of transmission
C. Route of transmission
D. Susceptible host

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2
Q

What are the sources of infection for disease transmission?

A
  1. individual suffering from acute infections “unlikely”
  2. individuals in prodromal stage of infection “coming down” (stage we should be worried about)
  3. Carrier (known and unknown)
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3
Q

What are some means of transmission?

A
  • hands
  • instruments
  • needles
  • teeth
  • saliva
  • tissue appliances
  • droplets and aerosols
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4
Q

What are the 3 main routes of transmission?

A
  1. Contact transmission: previously damaged skin or mucous membrane provides a portal of entry by touching
  2. Vehicle transmission: contaminated needles, sharp instruments or flying debris (blood)
  3. Airborne transmission: inhalation of contaminated aerosols
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5
Q

Susceptible host acquiring an infectious disease is influenced by:

A
  • route of exposure (more direct more infectious
  • host susceptibility
  • dose of micro-organism
  • # of exposure incidents
  • virulence of causative agent
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6
Q

What is the equation for chance of infection in a susceptible host?

A

Infection = (virulence of organisms X number of organisms) / resistance of host

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7
Q

Define universal precautions.

A

guidelines to reduce the risk of transmission of blood borne pathogens among DHCP and patients

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8
Q

Define standard precautions.

A

guidelines that combined the major components of universal precautions and body substance isolates. Additional precautions are necessary for interrupting the spread of certain diseases (eg. TB) transmitted by droplets, or indirect or direct contact with contaminated sources

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9
Q

What are the recommended immunizations for all staff?

A
  • HBV
  • influenza,
  • MMR,
  • polio
  • tetanus
  • whooping cough
  • TB
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10
Q

Define sterilization.

A

those processes by which all forms of microbial life are killed

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11
Q

Define disinfection.

A

those processes that result in the destruction of only the vegetative forms of microbial life (pathogenic MO)

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12
Q

Define antisepsis

A

the application of a chemical agent externally on a live surface (skin or mucosa) to destroy MO or inhibit their growth

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13
Q

Define bactriostatic.

A

a chemical agent interferes with cell division

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14
Q

Define bacteriocidal.

A

physical or chemical killing of the microorganism

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15
Q

What are some low resistance microorganisms?

A

most bacteria, viruses, fungi, Streptococcus facalis, salmonella choleraesuis, pseudomonas aeruginosa, staphlococcus aureus, hydrophilc viruses

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16
Q

What are some higher resistance microorganisms?

A

mycobacterium species, fungal endospores, bacterial endospores

Highest:
Creutzfeld-Jacob Disease
“Prion”

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17
Q

What are the two main types of sterilizers?

A
  1. Heat (main criteria for destroying microorganisms)

2. gas sterilizers: less used

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18
Q

What is gravity displacement (non-vacuum) sterilizer? Type? Pros and Cons?

A
  • superheated steam
  • unsaturated air expelled through vent
  • used to be popular, not anymore
    Type: steam sterilizer
    Pros:
  • good for solid unwrapped instruments
    Cons:
  • carbon steel instruments will rust
  • drying cycle can take 1 further hour
  • possibility of trapping expelled air
  • wrapped loads (depending on packaging) can fail
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19
Q

What is vacuum assisted sterilizer? Type? Pros and Cons?

A
  • systems create a vacuum before chamber is pressurized (now more popular)
  • allows faster and more positive steam penetration throughout the entire load
    Pros:
  • good for all types of loads
    Cons:
  • carbon steel instruments will rust
  • drying cycle can take 1 further hour
20
Q

What is chemical vapour sterilzers? Type? Pros and Cons?

A
  • use volatile chemicals (less than 12 % water)
  • a combination of formaldehyde, alcohol, acetone, ketone and STEAM
    Pros:
  • toxic action of chemicals and heat
    Cons:
  • sterilant vapours are an irritant to staff
21
Q

What is dry heat sterilizer? Type? Pros and Cons?

A 
- 160 degree cintigrade and has fan
Pros:
- used for instruments that rust
Cons:
- low temperature pockets
- cycle time 90 minutes
- damage to turbine hand pieces
- not used widely
22
Q

What are the variables contributing to ineffective sterilization monitoring?

A
  • mechanical
  • ineffective sterilants (chemoclaves)
  • incorrect wrapping/loading of instruments
  • operator error-temperature/exposure time
23
Q

What are the different kinds of sterilization monitoring tests used? What are their limitations?

A

1.Chemical indicators - not used appropriately
Limitations: does not indicate sterility
2. Biological monitors
Limitations: cannot be used for each sterilzation cycle
3. Spore strips
Procedure: put test strip inside a pack in a normal sterilzation load. Sterilze. Send to appropriate sterilzation service. - or use a self contained system.
Limitations: can’t use in every cycle

24
Q

What should you as future practitioners look for in a disinfectant?

A
  • the disinfectant should kill Polio Virus and Mycobacterium

- killing times should be about 3 minutes on surfaces - 5 minutes if blood is present

25
Q

What are the desirable properties of disinfectants?

A
  1. demonstrate of ability to destroy micro-organisms in low concentrations within minutes and should possess a broad spectrum anti-microbial action
  2. be soluble and stable in water or other solvent vehicles without the loss of killing power
  3. be relatively non-toxic for tissues
  4. show good penetration power on surface when applied and should not readily combine with organic matter
  5. be non-corrosive and non-staining
  6. have detergent and deodorant properties-effective and pleasant
26
Q

Factors affecting germicidal activity:

A
  1. concentration-determined by the manufacturer
  2. time of exposure-death rate should follow a logarithmic pattern relative to time of exposure
  3. Temperature- the higher the temperature the better
  4. pH - anionic detergents work at acidic pH while catonic detergents work at alkaline pH
  5. presence of contaminants - don’t want disinfectant to combine with organic matter
27
Q

What are halogens?

A

Disinfectants

a. Chlorine - sodium hypochlorite used in endodontics in irrigating root canals. forms hypochlorous acid
b. iodine - direct killing of micro-organisms
c. iodophors - made by combining iodine with a solubilizing agent. polyvinylpyrolidone can also be used as a surface or immersion disinfectant

28
Q

What are oxidizers?

A 
Disinfectant
hydrogen peroxide (H2O2) - reacts with SH groups of enzymes. used as mouth rinse in cases of ANUG
29
Q

What are heavy metal compounds?

A

Disinfectant

silver, mercury, arsenic, zinc. first used in the treatment of syphilis. silver used in dental unit waterlines

30
Q

What are alcohol?

A

Disinfectant
50-70% in water. Denatures proteins of micro-organisms. Not recommended as surface or immersion disinfectant. Ethyl alcohol or propyl alcohol.

31
Q

What are phenols (carbolic acid)?

A

Disinfectant
best are the bis-phenols (chlorhexadine); can be used as mouth rinses, to treat impression material as well as dental water lines (not an skin irritant)

32
Q

What are surface tension depressors?

A

Disinfectant

soaps and detergents; not recommended

33
Q

What are chemical aerosols, peracetic acid, dyes?

A

Disinfectant

exotics (not generally used in dental offices)

34
Q

What are aldehydes?

A

Disinfectant

a. formaldehyde - causes alkylation of protein of bacterial cell; isopropyl alcohol solutions of formaldehyde used for immersion disinfection
b. glutaraldehyde - recommended for general disinfection of instruments and apparatus(es)

Both are irritants to mucous membranes and can cause dermatological conditions

35
Q

What can disinfectants in dentistry be classified as?

A
  1. immersion disinfectants
  2. hard surface disinfectants
  3. disinfectants used in the dental unit water supply, drains and high velocity aspirators
36
Q

Name the targeted virulence components in a bacteria.

A

flagella
fimbriae (pili)
capsule

37
Q

Name the targeted structural components in a bacteria

A

cell wall

cytoplasmic membrane

38
Q

Name the functions of a flagella in bacteria.

A
  • locomtion- enables bacteria to follow concentration gradients, respond to physical stimuli and/or gain access to tissues
39
Q

Name the functions of fimbriae in bacteria.

A
  • adherence-receptors for surface of cells - allows higher replication numbers
  • aggregation - allows select bacteria to aggregate and form biofilm
  • can be found on gram +ve and gram -ve cells
40
Q

Name the functions of capsule in bacteria.

A
  • adherence - S. Mutans produces Mutan to help bind to the enamel surface
  • aggregation - used to help bacteria to associate - produce microenivornments
  • virulence - aids in avoiding phagocytosis
41
Q

Name the functions of cell wall in bacteria.

A
  • filters toxic components
  • physical protection
  • adherence
42
Q

Name the functions of cell membrane in bacteria.

A
  • filters toxic components
43
Q

What is sporulation? What type of bacteria is it associated with?

A
  • defence mechanism against death caused by adverse environmental conditions
  • associated with gram +ve bacteria
44
Q

What are the 3 main sturctures in human viruses?

A
  • peplomers or “spikes”
  • viral envelop
  • nucleocapsid
45
Q

What are the targets of fungi?

A
  • flagella
  • cell wall
  • cell membrane
46
Q

What are the targets in protozoa

A
  • cell membrane
47
Q

What are Prions?

A

“Infectious Proteins”

Prions enter brain cells and there convert the normal cell protein PrPC to the prion form of the protein, called PrPSC. When normal cell proteins transform into prions, amino acids that are folded tightly into alpha helical structures relax into looser beta sheets. More and more PrPC molecules transform into PrPSC molecules, until eventually prions completely clog the infected brain cells. The cells misfire, work poorly or don’t work at all.

DENT 410 - IPA (1 decks)

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