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Microbiology Lab > lab 10 > Flashcards

lab 10 Flashcards

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1
Q

Understand the effects of physical and chemical agents on different types of bacteria
Highest resistance?

A
  • Prions

- Bacterial endospores

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2
Q

Understand the effects of physical and chemical agents on different types of bacteria
Moderate resistance?

A
  • protozoan cysts
  • some fungal sexual spores
  • naked viruses
  • bacteria with more resistant vegetative cells (some gram -/+)
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3
Q

Understand the effects of physical and chemical agents on different types of bacteria
Least resistance?

A
  • typical bacterial vegetative cells
  • fungal spores and hyphae
  • enveloped viruses
  • yeast
  • protozoan trophozoites
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4
Q

Define Sterilization

A

“complete removal” or destruction of all transmissible agents (microbes, spores, viruses)

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5
Q

name 5 ways to sterilize an inanimate object

A 
Autoclaving (steam heat)
Heat
Radiation (not UV)
Strong chemicals (liquids and gases)
Filtration
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6
Q

Define Disinfection

A

Destruction/removal of vegetative microbes (no bacterial endospores). Used on Inanimate objects due to intensity of treatment required to be effective.
Physical agent.

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7
Q

Define antisepsis

A

Chemical applied to body surfaces to destroy or inhibit vegetative microbes. Chemical agent

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8
Q

Name 6 ways to Disinfect

A 
Lysol
Cidex (an aldehyde, alkylating agent)
Bleach
Heat
UV
Boiling water
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9
Q

Name 4 antisepsis

A

Alcohols (60-90%) - hand sanitizers
Hydrogen peroxide (3-6%)
Betadine (iodine compound and therefore a halogen)
Saline (>0.9%)

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10
Q

Define Sanitization/Degermation

A

destruction/physical removal of transmissible agents to safe level on inanimate/animate surfaces

  • methods vary, combined physical and chemical, mechanical scrubbing, soaps, disinfection, antisepsis
  • Soaps - cleansing and wetting agent that enhances the physical removal of microbes and debris but does not kill microbes
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11
Q

Define Microbicide

A

kills microbes

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12
Q

Define Fungicides

A

kills fungal hypae, spores, yeast and molds

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13
Q

Define Bactericeds

A

kills bacteria

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14
Q

Define Viricides

A

kills viruses

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15
Q

3 microbial control methods

A

Physical (boiling water, hot water, pasteurization, non ionizing and UV), Chemical (liquids) and Mechanical removal method

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16
Q

What does MOIST heat kill? Temp?

A

Vegetative cell - 80C required to kill most resistant cells
Spores/endospores - 120C required to kill most resistant spores. More resistant to heat than vegetative cells, but not invincible to heat. Resistance aided by cortex, proteins, minerals, DPA

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17
Q

Effects of Ultraviolet Light

A

Disinfectant which kills most but not all microbes.
UV mutate DNA by causing dimers to thymine and cytosine (pyrimidines)
Enzymes can sometimes repair DNA damage
Cause of skin melanomas
Common method used to disinfect equipment

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18
Q

What is Kirby-Bauer Susceptibility Test?

A

standardized test that follows a specific testing procedure to determine the susceptibility of bacteria to antimicrobial agents.
results are used to determine the correct antimicrobial agent to be prescribed to the patient

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19
Q

3 Kirby-Bauer Susceptibility test designation

A

Resistant, Intermediate, Susceptible

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20
Q

Define Resistant in terms of the Kirby test

A

organism is NOT KILLED or inhibited by the tested antimicrobial in blood or other body fluids

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21
Q

Define Intermediate in terms of the Kirby test

A

organism MAY NOT BE KILLED or inhibited by the tested antimicrobial in blood or other body fluids

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22
Q

Define Susceptible in terms of the Kirby test

A

organism is KILLED or inhibited by the tested antimicrobial in blood or other body fluids

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23
Q

Operating parameters for autoclave

A

Temp, 121.5C
Pressure, 15 psi
Time, 15-20 min

24
Q

Define Penicillinase

A

An enzyme produced by penicillin resistant strains of bacteria to inactive penicillin

25
Q

4 things that must be standardized in the Kirby Bauer sensitivity test

A

Mueller-Hinton agar poured at 4mm thickness
Standardized antibiotic disks are used (size of disk and concentration of chemical)
Standardized inoculum used. Compared to a McFarland standard
Incubate plates for 18-24 hours at 37C
This allows for reproducible results

26
Q

Is it correct to say that dish washing sterilizes dishes?

A

No, its sanitizing agent only

27
Q

Soaps are strong microbicides?

A

False

28
Q

all gram negative bacteria have an outer layer of the outer membrane that consists of?

A

LPS, Lipid A and porin proteins

29
Q

Disinfection is a cleansing process that destroys vegetative pathogens and endospores

A

False

30
Q

Autoclaving uses steam heat as a sterilizing agent. Of the following choose which method of controlling microbes this fits

a. chemical
b. physical
c. mechanical
d. chemical and mechanical

A

Physical

31
Q

a fungicidal agent has what effects?

A

destroys fungal spores, hyphea and yeast growth

32
Q

Which of the following is safe to use on or near living tissue

a. antiseptic
d. disinfectant
c. aldehydes
d. ethylene oxide

A

Antiseptic

33
Q

Starting at the core of an endospore the protective layers from the inside out?

A

cortex, spore coat, exosporium coat

34
Q

when attempting to sterilize endospores using autoclace the temp must reach 100c at 3psi for 5 min.

A

False
temp 121C
15psi
15-20 min
to effectively destroy bacterial spores and endospores.
The pressure drives the steam heat into the cells and keeps water from boiling.

35
Q

UV radiation is usually considered a disinfectant rather than a sterilizer. UV radiation is 99% effective in decreasing concentration of air borne microbes

A

True

36
Q

The Kirby Bauer method determines susceptibility of organisms to antimicrobial agents. The results are compared to a standardized range for each drug and a determination is made as to whether the organism is susceptible, resistant, or intermediate to a particular drug concentration.

A

True

37
Q 
What is gram negative and what is gram positive of the following:
Staphylococcus aureus
Bacillus sp
Escherichia coli
Pseudomonas sp
A

Staphylococcus aureus Gram Positive
Bacillus sp Gram Positive
Esherichia coli Gram Negative
Pseudomonas sp Gram Negative

38
Q

Which organisms are spore former?

A

Bacillus sp and C-Dif

39
Q

Cell envelope structure of Gram positive, from out to in

A 
Wall teichoic acid
Lipoteichoic acid
Thick Peptidoglycan
Periplasmic space
Cell membrane
Membrane proteins
40
Q

Cell envelope structure of Gram negative, from out to in

A 
Porin proteins
LPS
Outer membrane layer
Phospholipids
Lipoproteins
Thin peptidoglycan
Periplasmic space
Cell membrane
Membrane protein
41
Q

Bacterial endospores contain?

A 
Exosporium
Spore Coat
Outer Membrane
Cortex
Intermembrane
Spore Cell
*highly resistance due to membranes/materials
42
Q

Define Sporocide

A

Kills all spores

43
Q

Define decontamination

A

The mechanical removal of most microbes

44
Q

Mueller Hinton plate info

A

Standard medium
4mm thick agar
neutral pH
Grows most non-fastidious bacteria

45
Q

What do we call a microbe that thrives in a rich carbon dioxide environments?

A

Capnophile- obligate anaerobes

46
Q

How are Autoclaves routinely tested?

A

Using spore strips from Bacillus stearothermophilus - commonly used thermophile used to validate sterilization processes and the checking growth

47
Q

3 forms of heat? Effects?

A

Dry, moist and steam
Gradual exposure to increasing temperatures may enable cells to adapt to higher “lethal” levels by producing heat shock protein in attempt to protect cell integrity

48
Q

Define cidal (evaluation of chemical antimicrobial agents)

A

If the chemical kills the microorganism, it said to be cidal

49
Q

Define static (evaluation of chemical antimicrobial agents)

A

If the chemical inhibits growth, it is said to be static

50
Q

What does MIC stand for?

A

Minimum Inhibitory Concentration

Smallest concentration of drug in the series that visibly inhibits growth

51
Q

What does MIC useful for?

A

Useful in determining the most effective dosage of a drug and in providing a comparative index against other antimicrobial.

52
Q

Similarities between agar diffusion (Kirby Bauer) and tube dilution sensitivity tests

A

Similarities:
Both test organisms for antimicrobial susceptibility
Standardized tests
Determine the specific antimicrobial that is most effective in treating that particular strain of bacteria

53
Q

Differences between agar diffusion (Kirby Bauer) and tube dilution sensitivity tests

A

Differences:
KB uses a Mueller-Hilton agar, MIC uses a dilution tray containing a supporting medium
MIC provides the minimum dilution of an antibiotic that would be effective in treating a specific bacterial infection, KB does not

54
Q

Moist heat and dry heat differ in their modes of action as well as in their efficiency.

A

Moist heat operates at lower temperatures and shorter exposure time to achieve the same effectiveness as the dry heat

55
Q

Kirby Bauer test infor

A

Agar diffusion
Measure diameter in mm around disc
If not clear enter 6mm for disk diameter
If overlap, use radius X2

Microbiology Lab (12 decks)

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