Lecture 6: Growth Control Flashcards Preview

BIO 425: Microbiology > Lecture 6: Growth Control > Flashcards

Flashcards in Lecture 6: Growth Control Deck (32)
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1
Q

What methods are available to control microbial growth?

A

Sterilization: Kill all microbes

Disinfection: Inhibit growth on inanimate surface

Antisepsis: Inhibit growth on living tissue

2
Q

What are the methods of sterilization?

A

Heat, Radiation, Filters

3
Q

What is the heat sterilization?

A

Denatures macromolecules making them lose structure/function

  • Decimal Reduction Time: 10-fold reduction
  • Thermal death time: Time to KILL ALL microbes
4
Q

What equipment will you use for heat sterilization?

A

Autoclave

  • Up to 121 degrees Celsius
  • Uses steam to get endospores to hatch (endospores resistant to 150 degrees celsius)
5
Q

What method is used for heat growth control?

A

Pasteurization
-Rapid heating/cooling

Does not KILL ALL microbes but REDUCES number

6
Q

What are the types of radiation sterilization?

A

UV Radiation
-mutates DNA

Ionizing Radiation
-Radicals tear proteins/lipids apart

7
Q

What is UV radiation sterilization?

A

Expose to UV waves

Advantage: Practical and Safer
Disadvantage: Sterilize surface only

8
Q

What is Ionizing radiation sterilization?

A

Expose to Electromagnetic radiation

Advantage: Cold sterilization penetrate solid/liquid
Disadvantage: DANGEROUS

9
Q

What is filter sterilization?

A

Sterilization without heat that uses filters

Advantage: Safe and useful for heat sensitive microbe
Disadvantage: Cant use on solids

10
Q

What are Depth Filters?

A

Filter sterilization uses glass fibers to make 3d spiderweb

11
Q

What are membrane and nucleopore filters?

A

Filter sterilization uses strong polymers to trap microbe

Nucleopore filters use polycarbonate film with specific and controllable pore sizes to trap microbe

12
Q

What is a chemical that kills or inhibits microbial growth?

A

Antimicrobial agent

13
Q

What are the classifications of antimicrobial agents?

A

Target Organism
-Bacterio-, Fungi-, Viri-

Action

  • static= stop growth (plateau total+viable cell count)
  • cidal= kills cells (decrease viable cell count)
  • lytic=kills+lyses cells (decrease total cell count)
14
Q

What is targeted by bacteriostatic, bateriocidal, and bateriolytic antimicrobial agents?

A

Bacteriostatic-ribosomes, prevent protein synthesis

Bacteriocidal-bins specific cellular targets

Bacteriolytic-cell wall+membranes=lysis

15
Q

What is the Minimum Inhibitory Concentration (MIC)?

A

Amount of chemical needed to inhibit growth

16
Q

What kinds of antimicrobial agents would you use on inanimate surfaces and external body surfaces?

A

Inanimate surfaces
-Sterilants and Disinfectants

External Body Surfaces
-Antiseptics (germicides)

17
Q

What do sterilants do? What would you use them for?

A

KILL ALL microbial cells and endospores

Use on heat-sensitive equipment

18
Q

What do Disinfectants do? What would you use them for?

A

Kill ALL microbial cell but NOT endospores

Used on home surfaces

19
Q

What do Antiseptics (germicides) do? What would you use them for?

A

Kill Microbial cells or inhibit growth (non-toxic)

Used in Handwashing soaps

20
Q

What are the different structural classes of antimicrobial drugs which kill and inhibit microbial growth INSIDE the body?

A
B-Lactam = 52%
Fluoroquinolones = 24%
Macrolide = 20%
Other = 4%
21
Q

What class of drug is penicillin?

A

B-Lactam

22
Q

What are some of the targets of antimicrobial drugs?

A

DNA translation

RNA Elongation

DNA Gyrase (only in bacteria)

Folic Acid Synthesis

Cell Wall Synthesis

23
Q

Who is Paul Ehrlich and what is selective toxicity?

A

Paul Ehrlich responsible for magic bullet approach to antimicrobial drugs

Selective toxicity is the goal of antimicrobial drugs
-inhibit or kill microbial pathogens and don’t harm human

24
Q

What are Sulfa antimicrobial drugs? What is its mechanism and spectrum?

A

Synthetic Antimicrobial Drug

  • Mechanism: Interfere with folic acid synthesis (DNA)
  • Spectrum: Broad, Gram + and Gram -
25
Q

What are QUINILONES antimicrobial drugs? What is its mechanism and spectrum?

A

Synthetic Antimicrobial Drug

  • Mechanism: Interfere with DNA Gyrase
  • Spectrum: Broad, Gram + and Gram -
26
Q

What are ISONIAZID antimicrobial drugs? What is its mechanism and spectrum?

A

Synthetic Antimicrobial Drug

  • Mechanism: Interfere with Mycolic Acid
  • Spectrum: Mycobacterium (Broad)

Mycolic Acid makes waxy cell wall, hard for other drugs to penetrate

27
Q

What are the types of Natural antimicrobial drugs?

A

Antibiotics

  • Produced by microbes
  • Many know, few useful (selective toxicity)

Semi-Synthetic
-Artifically modified antibiotics

28
Q

What are B-Lactam antibiotics?

A

Semi-Synthetic Antibiotic, Example: Penicillin

  • Mechanism: Interfere w/ cell wall
  • Spectrum: Gram +, Gram -. Intracellular (broad)

prevents peptidoglycan synthesis

29
Q

What are Macrolides?

A

Semisynthetic Antibiotic, Example: Erythromycin

  • Mechanism: Interfere with protein synthesis (translation)
  • Spectrum: Gram +, Gram -, broad
30
Q

What is the problem with Anti-viral and Anti-Fungal drugs?

A

Can also affect host cells

31
Q

What is an example of antiviral drug?

A

Azidothymidine (AZT)

  • HIV Treatment
  • Resembles nucleotide Thymidine
  • prevents reverse transription (RNA->DNA)
32
Q

What are the types of antifungal drugs and what is an example of each?

A

Topical Drugs
-Surface application

Fungi Specific Drugs
-target specific processes/structures

Ergosterol Inhibitors prevent synthesis of this cholestrol found in fungi cytoplasmic membranes