Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology 1 > Lecture #6 - Control of Microbial Growth > Flashcards

Lecture #6 - Control of Microbial Growth Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Control of microbial growth take away:

A

How can we take everything we learned about so far to gain a better understanding of how it is these organisms are gonna live & do their thing & kill them or inhibit them in order to protect ourselves against infection & our food against spoilage etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Sterilization

A

• The killing or removal of all viable organisms within a growth medium

ABSOLUTE DESTRUCTION OF EVERTHING! - pathogenic or non-path, all virus, & ENDOSPORES)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Inhibition

A

• Effectively LIMITING microbial GROWTH
- NOT able to complete binary fission & NOT able to increase cell #

• NO killing taking place

ORGANISM IS NOT BEING KILLED/PERSISTS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Bacteriostatic =

A

holds cell # constant

inhibits growth/does not kill

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Bacteriocidal =

A

kill organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

If we’re describing an antibiotic that’s being used inside of a person’s body & that antibiotic is deemed bacterioSTATIC, what are you also relying on in this ex?

A

HAVE TO HAVE AN IMMUNE SYSTEM - b/c if they don’t & they finish their 5-day course of antibiotic, as soon as that antibiotic drops in concentration in their blood for good, those ORGANISMS are STILL THERE, they’re JUST BEEN GROWTH ARRESTED (gonna start doing binary fission & increase their # again)

  • so you cannot give a bacteriostatic drug to a patient who’s just had a bone marrow transplant & is in immunosuppressant therapy
  • you can’t give a bacteriostatic drug to a patient that has AIDS & doesn’t have much of an adaptive immune system to work with

need to consider you patient in order to understand the type of therapy that’ll make the most sense - sometimes if the immune systems not there, you need to do the killing by actually using the organism all together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Decontamination

A

• The treatment of an object to make it safe to handle (SAFETY)

= SANITIZE

  • removing organisms in MASS - but NOT killing specific ones, NOT making sure all gone, just trying to DECREASE THE #’s (make sure nutrients are gone or any organism that might’ve been contaminating will have a good chance of being removed so there’s fewer left behind at the end)
  • outcome: benefit to person

ex: wash dishes, wash hands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Disinfection

A

• Directly targets the REMOVAL OF ALL PATHOGENS (cause disease)

  • organisms that have the capacity to cause the disease are the ones that’ll be eliminated in their entirety & then the organisms that are left behind are at the v. least non-path & not worrisome
  • ex: pasteurization - eliminating path. from milk or apple juice for ex & then eliminating some other ones as well, so when milk gets to shelf it has the capacity to last long (extend shelf-life & making sure organisms capable of disease are gonna be eliminated)

• Not necessarily all microorganisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Heat sterilization

A

is the MOST WIDELY USED METHOD of CONTROLLING microbial GROWTH
- MOST EFFECTIVE way to ELIMINATE PROBLEMATIC ORGANISMS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Heat Sterilization dets

A

• HIGH TEMPERATURES DENATURE MACROMOLECULES

  • breaks low energy bonds (VdW’s, ionic & H-bonds) that were holding the folded conformation of protein together)
  • change in shape renders the molecule non-functional (think: key had shape change)
  • DNA gets denatured b/c H-bonds are v. weak & easy to break that hold them together
  • ds DNA characteristics genome of living organisms so you anticipate that’ll break & denature
  • & VdW’s ints. & f.a tails - PM integrity (PM structure will also be disturbed as a result of heat treatment)

• Amount of time required to reduce viability tenfold (get efforts your looking for) is called the DECIMAL REDUCTION TIME (D)

  • Time it takes for a 10 fold reduction in bacterial numbers
    ex: 100 bacteria ten fold will be 10
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Heat Sterilization

Some bacteria produce resistant cells called…

A

endospores
• Can survive heat that would rapidly kill vegetative cells

  • highly resistant to heat, which means we have to consider they may be present
  • if in endospore state, not effective to eliminate them
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

If you take temp you were exposing organisms to, & now increase it by 10 degrees celsius, D is now 10 mins…

A

therefore to reduce pop. 10 fold it only takes us 10 mins (massive)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Time is money (explain in terms of Heat Sterilization)

A
  • if you just increase temp 20 degrees celsius & find it gives a much faster D, which in turn means you don’t have to process your material for nearly as long, that’ll be what you chose
  • want to be sure you’re preserving content/desirability/characteristics or your material
  • want to drink milk after pasteurization (make sure perserved)
  • preservation of the content, @ the same time making it most efficient with respect to time, & achieving the reduction that you need to
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Pasteurization:

A

is the process of using precisely CONTROLLED HEAT to REDUCE the MICROBIAL LOAD IN HEAT-SENSITIVE LIQUIDS

(process used to take something that is technically heat sensitive to a certain degree & eliminate disease causing organisms & reduce counts of organisms overall so SHELF LIFE of the material will be EXTENDED so someone profits from that & we meet needs of society (eat or drink)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Pasteurization does…

A

NOT kill all organisms -> not sterilization (DISINFECTION)
- always organisms in this case, even if you haven’t opened sealed carton - means pasteurization process wasn’t sterilization but rather was called DISINFECTION - make sure disease causing organisms are eliminated & total counts are reduced, but organisms are still present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In the case of milk many different time and temperature combinations can be used…

A

(balance temp/time make sure material is still desired/want to consume)

  • LTLT (low-temperature/long-time)
  • 63oC for 30 MINUTES

• HTST (high-temperature/short-time)
• 72oC for 15 SECONDS (more than 30 fold reduced)
* - desired b/c it reduces exposure time to the point where you can process so much more - EFFICIENCY (time is money)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which is desired?

  • LTLT (low-temperature/long-time)
  • 63oC for 30 minutes

OR

  • HTST (high-temperature/short-time)
  • 72oC for 15 seconds
A

HTST is desired b/c it reduces exposure time to the point where you can process so much more - efficiency (time is money)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q
  • LTLT (low-temperature/long-time)
  • 63oC for 30 minutes

&

  • HTST (high-temperature/short-time)
  • 72oC for 15 seconds

Both processes…

A

kill Coxiella burnetii, the causative agent of Q fever (disease), which is the most heat resistant pathogen found in milk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

UHT ultra high temp…

A

> 100 degrees celsius for 3 seconds

- useful in places where refrigeration is not an option but want to still provide protection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

The Autoclave

A

The autoclave is a sealed device that uses steam under pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The Autoclave allows…

A

Allows temperature of water to get ABOVE 100oC (which normally would be vapourization point)

121oC for 15 min at 15 pounds per square inch of pressure is typically used

To ensure sterility this means that the point that takes the longest to heat must stay at 121 for 15 min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the reason for how the autoclave “Allows temperature of water to get above 100oC”? As it normally would be the vapourization point

A

reason: COMBINE IT WITH PRESSURE
- forces water molecule which will normally have H-bonds broken @ 100oC to stay proximal to 1 another so you continuously have H-bonds formed to keep it in a liq state
- 3.4 on average per water molecule is what you expect in liq state, zero H-bonds per molecule in the vapourized state
- therefore, forcing H-bonds to stay, maintaining liq state & moist heat is v. effective at transferring that heat to cooler objects its in contact with (opposite of dry heat)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

The Autoclave is #1 for…

A

TRUE STERILIZATION

  • EVERYTHING is GONE: endospores, viruses (no longer infectious), bacteria (path & non-path)
  • complete destruction of any life form, either DORMANT OR NOT
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are 2 imp. things about the autoclave?

A
  1. When the material 1st starts flowing in (steam coming in), you have to LET the CONDITIONS CLIMB before you let the material in (like an oven)
    - in doing so you’ll let it reach the conditions necessary for sterilization (121oC)
    - once those conditions initiate, it has to be kept for 15 mins at that set of conditions & only then can you ensure an adequate sterilizing process
    - then you can let conditions level off (pressure dissipate, temp comes down) & you have to leave it for a while so its cool & then at that point you can handle it
  2. RECEIPT that shows pressure & temp combos at each time point, that’ll INDICATE what the CYCLE LOOKS LIKE & ENSURE they’re ON POINT
    - also a vial inside that you leave & test to see if there’s any growth
    - after there’s no growth, after a defined period of time that went through autoclave cycle, you can ensure it would’ve been effective
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Radiation

A

• PHYSICAL method of growth control - applying some material that can impart damage on the inside of the cell
- NOT applying chemical

  • Microwaves, UV, X-rays, gamma rays, and electrons (have higher amount of energy) can REDUCE microbial growth
  • UV has sufficient energy to cause modifications and breaks in DNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Radiation

____ has sufficient energy (in the ____ wavelength that it’s characterized by) to cause modifications and breaks in DNA (that are capable of absorbing light)

A

UV

SHORT

  • UV is USEFUL for DECONTAMINATING surfaces
  • CANNOT PENETRATE solid, opaque, or light-absorbing surfaces
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Microwave = ____ wavelength

= ____ energy

A

LONG

LOW

BUT in a high freq., it transfers a lot of energy that is heating food up & it’ll serve to destroy the organism in there to a lesser degree

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

_____ indicates the # of waves that are passing a point through unit time. Will make for ____ amount of energy delivery

A

FREQUENCY

INCREASED

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Ionizing radiation

A
  • look for decimal 10 value, where 10% of what we started with is left over (surviving)
  • certain amount of radiation needs to be applied in order to give us that elimination (D10 value) & it’s measured in Grays
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Ionizing radiation will be diff. depending on…

A

MODE OF RADIATION WE CHOOSE:

  • if we chose a HIGH energy, the amount of radiation that needs to be imparted on our material in order to give us the decimal 10 value is gonna be less

OR

  • if we chose a LOWER energy, you’ll need more in order to accomplish the same thing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Ionizing radiation (FULL DETS)

A
  • Electromagnetic radiation that produces ions and other reactive molecules generates electrons, hydroxyl radicals, and hydride radicals.
  • Some microorganisms are more resistant to radiation than others.
  • amount of energy required to reduce viability tenfold is analogous to D value
32
Q

What is the reason radiation is so damaging?

A

b/c it encourages the formation of IONIZING RADICALS

  • superoxide, hydroxyl radical, free e-‘s trying to find pair, hydride radicals etc.
  • forming incredibly reactive structures that will chose to make engagements with your systems in order to impart that damage
  • to react with your DNA, protein is where these probs arise
33
Q

Some microorganisms are more resistant to radiation than others.

For ex:

A

Deinococcus radiodurans
RADIATION RESISTANT
- has elaborate DNA repair mechanisms
- amount of energy req. to reduce the viability 10 fold is the D value some organisms aren’t bothered by, even if its effective against many organisms that we might encounter

34
Q

Deinococcus radiodurans

From nomenclature of this species what can you predict about this organism?

A

RADIATION RESISTANT

35
Q

Where do we get radiation from in order to accomplish these tasks (form ionized structures that are highly reactive, to cause damage to DNA & other structures that the organism req’s for survival)?

A

Sources of radiation include cathode ray tubes, X-rays, and radioactive nuclides

36
Q

Sources of radiation include:

A

cathode ray tubes, X-rays, and radioactive nuclides (for decontamination & removal of organisms)

37
Q

Radiation is used for sterilization in the…

A

MEDICAL FIELD (ex: remove organisms from medical utensils, to make them safe for use) AND FOOD INDUSTRY
• Radiation is approved by the WHO and is used in the USA for decontaminating foods particularly susceptible to microbial contamination
• Hamburger, chicken, (meat - make sure no path organisms present) spices may all be irradiated

38
Q

Radiation

Think:

A

recipe book with all vial recipes, (& what you’re doing with ionized radiation to the chromosome or plasmid of bacterium is like), going into recipe for choco chip cookies & sneaking out 1 cup of sugar for salt
- critical change - product is totally diff (just like how ionized radiation cause damage to the DNA structure, words its encoding is diff. & outcome is you end up with a product that won’t be of benefit to the organism any more)

39
Q

Will the food be sterile when it gets to you? (after radiation)

A

NO - b/c it will end up having contaminants that’ve been picked up just from exposure to the envir. etc.
- food industry concern is to eliminate disease causing to ensure you have the least likelihood of dev. food-borne illness

40
Q

Filtration

A

AVOIDS the use of HEAT ON SENSITIVE LIQUIDS AND GASES

  • accomplish purification & sterilization (if there were no other infectious material there other than bug)
  • now material can be safe for concentration & distribution

PORES of filter are TOO SMALL for organisms to pass through
• ALLOW LIQUID OR GAS to pass through
• Ex) HEPA filters (High Efficiency Particulate Air - ex: an operating table - NOT passing unfiltered air through that room with this decrease likely of hospital infection to occur), membrane filters

41
Q

With membrane filters, filtration can be accomplished by:

A
  • Syringe
  • Pump
  • Vacuum

(driving force)

bugs remain on filter

& protein in bottom

42
Q

Filtration ex:

A

E. coli can be used as a workhorse in a facility to make proteins for us
ex: insulin use to be taken from cadavers & other animals & cause problems b/c out body knew it wasn’t ours but now we can use human insulin with gene therapy (give it to E. coli)

E. coli is:

  • easy to manipulate
  • not picky
  • grow quick & effective
  • hospitable to uptake of genetic material

Outcome: opp. to pass gene along to organism, where it’ll start to make that insulin protein & secrete it to outside of cell

  • insulin is now avail. to be purified & concentrated to be distributed to diabetic patients to help control their disease
  • but prob. is it has lots of E. coli at a particular moment of time, so you have to eliminate E. coli before you distribute to patients by filtration (for heat sensitive materials)
43
Q

Filtration

a) Pore size is 5 μm

Is this an appropriate filter to prevent bacteria from going through?

A

• Note the size of the pores relative to the size of some of the bacteria

NOT AN EFFECTIVE FILTER - b/c the organisms can fit through

44
Q

Filtration

b) Pore size 0.2 μm

Is this an appropriate filter to prevent bacteria from going through?

Note the pore size relative to Leptospira (0.1 x 20 μm)

A

• This filter PREVENTS most bacteria from going through

  • doesn’t have ability to move through to other side
  • therefore, efficiently trapped & filtered the organism
45
Q

Would this pore size (Pore size 0.2 μm) be effective to stop the movement of virus through?

Note the pore size relative to Leptospira (0.1 x 20 μm)

A

NO - but not concerned b/c insulin for ex is made in a quality controlled facility (a lot of measures in place so insulin won’t be there)
- therefore, Yes, the pore size will allow viruses for most part to be able to get through, but where would the virus come from (wouldn’t have to worry b/c shouldn’t be there in 1st place)

46
Q

Chemical Control of Microbial Growth

Antimicrobial agents can be classified as:

A

Bacteriostatic

Bacteriocidal

Bacteriolytic

LOOK AT SLIDE 11 figures

47
Q

Bacteriostatic:

A

prevents cell growth as long as the antimicrobial agent is
present
- viable cell count & total cell count increase

48
Q

Bacteriocidal:

A

kills the cells (does not lyse them)
- BUT leaves the BODIES INTACT PHYSICALLY

  • VIABLE cell count DECREASE b/c organism is dead
  • TOTAL cell count stays CONSTANT b/c COUNTING BODIES (dead or alive)
49
Q

Bacteriolytic:

A

kills and lyses the cells
- NO physical bodies present

  • viable cell count & total cell count both down
50
Q

Start with 2 bacteria:

@ start t=not 0

  1. Chemotherapy that is bacterioSTATIC
  2. Chemotherapy is STOPPED
A
  1. still have 2 viable bacteria
  2. filtered & broken down by system
    - binary fission resumes #’s increases
    - b/c still viable (weren’t destroyed)

IMMUNE SYSTEM KILLS ORGANISM HERE (b/t them)

51
Q

If this was a drug you took into your body in order to help treat an infection. What would you have hoped to happen b/t step 1 & 2?

A

IMMUNE SYSTEM SHOULD’VE KILLED THEM OFF

52
Q

Chemical Control of Microbial Growth

Minimum inhibitory concentration (MIC)

A
  • The SMALLEST AMOUNT of an AGENT needed to INHIBIT GROWTH of a microorganism
  • VARIES with the organism used, inoculum size (how much bacteria present - how much drug needed), temperature (drugs are CHEMICAL - if you turn up temp on a chemical rxn, it’ll go faster so amount you need will be affected), pH (has to tolerate the areas inside the body), etc.
  • some organisms are harder to destroy than others
  • may need higher or lower concentration for diff. species
53
Q

If the acidity poses a prob., the outcome is you must use the drug…

A

peventially

- drug inoculated through venous system (blood supply instead of oral cavity)

54
Q

Minimum inhibitory concentration (MIC)

Increasing concentration of antibiotic from…

A

left to right.

55
Q

Minimum inhibitory concentration (MIC)

Lowest concentration with no growth =

A

MIC
(clear - no turbity)

• May still have living (non-growing) organisms
• i.e. the antibiotic may be bacteriostatic
- just inhibiting growth - are the bugs in tube living or dead?
- alive - req. a functional immune system if used in human host

56
Q

Therefore, have to take petri plate with nutrients & take MIC (1 ml) & if you see growth it tells you the antibiotic is _______ b/c organism is still able to grow

A

BACTERIOSTATIC

57
Q

Therefore, have to take petri plate with nutrients & take MIC (1 ml) & if you DON’T see growth it tells you the antibiotic is _______

A

bacteriolytic or bacteriocidal

  • never grow
  • to determine which 1, you look under microscope & see if there’s physical bodies
58
Q

Minimum inhibitory concentration (MIC) PROCESS

A

Plate aliquots of broth from the MIC and from tubes with higher concentrations of antibiotic, on appropriate nutrient agar plates, without antibiotic
• Do colonies form?

59
Q

No colonies =

A

Minimal Lethal Concentration (MLC) (kills)

60
Q

MLC usually ____ than MIC

A

HIGHER

- kills

61
Q

Which test tube concentration of antibiotic would you provide your patient?

A

MIC - chose one that has lowest cost & material

- if you go higher cost goes up

62
Q

If you have a drug that can both inhibit & kill the diff. b/t them is typically…

A

concentration

63
Q

If bacteriostatic, it’s…

A

NOT killing at all, so MIC isn’t a thing

64
Q

How would you determine if it were bacteriolytic/cidal?

A

use microscope to test for bodies

65
Q

Chemical Control of Microbial Growth

Disc diffusion assay

A
  • Uses solid media
  • Antimicrobial agent is added to filter paper disc
  • The MIC is reached at some distance
  • Forms a zone of inhibition
  • Area of no growth around disc
66
Q

Chemical Control of Microbial Growth

Disc diffusion assay

Think: if you feel sick & go to doctor for sore throat, they’ll take swab from throat & put on petri dish that will have nutrients effective to grow the organism most expected (ex: staphylococcus, etc.) &…

A
  • will put FILTER PAPER soaked with antibiotic onto it
  • on 1 of them it’ll include the antibiotic you were given to treat your infection, but also other antibiotics
  • put in incubator & tomorrow see
67
Q

What if there is no zone of growth inhibition on disc diffusion assay?

A

RESISTANT - bugs growing right up to filter paper

ANTIBIOTIC didn’t work

68
Q

Which will be more efficient: a smaller or wider zone of inhibition (clearing) for disc diffusion assay?

A

WIDER zone of clearance

- more POTENT - organism can’t get really close to organism without dying or inhibited)

69
Q

All things considered (all drugs are same cost, same selective toxicity, etc.), want 1 with…

A

WIDEST zone of clearing

70
Q

Chemical Control of Microbial Growth

These antimicrobial agents can be divided into two categories:

A
  1. Products used to control microorganisms in commercial and industrial applications
  2. Products designed to prevent growth of human pathogens in inanimate environments and on external body surfaces
71
Q
  1. Products used to control microorganisms in commercial and industrial applications
A

Ex) chemicals in foods, air conditioning cooling towers (droplets of moisture have capacity to spread infectious material), textile (protect fabrics, write on or produce clothing) and paper products, fuel tanks (lipid (octane) inside that’s an imp. enzyme source that can be oxidized in order to receive energy - want to prevent contamination))
- roofing shingles - prone to algael growth

72
Q
  1. Products designed to prevent growth of human pathogens in inanimate environments (toilet ex) and on external body surfaces
A
  • Sterilant
  • Disinfectant
  • Sanitizer
  • Antiseptic
73
Q

Sterilant:

A

destroys all microorganisms including endospores (EVERYTHING)
- bacterial contaminants, infectious viruses, parasites & endospores

74
Q

Disinfectant:

A

kills microorganisms but not all endspores.
• Used on inanimate objects *NOT used in/on bodily surfaces (b/c tending to be more harsh)
* pathogens will be destroyed

ex: Lysol to clean bathroom

75
Q

Sanitizer:

A

reduces the numbers of microorganisms on surfaces (e.g. hand sanitizers)

  • some might be pathogenic & some not
  • but by decreasing those counts, the likelihood of infection happening will be minimized
    • makes things safe for use by reducing microbial counts
76
Q

Antiseptic:

A

kills or inhibits the growth of microorganisms (non-toxic enough to be applied ON LIVING TISSUE (e.g. mouth wash))

*disinfectants meant for use on LIVING TISSUE!

    • LIKE DISINFECTANT but with a gentle composition; only destroys organism while leaving OWN TISSUE UNHARMED
  • SKIN IS DEAD - therefore, outermost layer is dead epithelial cells
  • don’t compromise any living tissue on surfaces of your skin, so to apply things there it’s imp. to remove organisms that are considered contaminants which have capacity to cause disease or threat
  • BUT INSIDE of body is rich with LIVING TISSUE

Microbiology 1 (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions