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Flashcards in Chapter 26 Deck (61)
1

What is sterilization

The killing or removal of ALL viable organisms

2

What is inhibition

Effectively limiting/inhibiting microbial growth. Ex. dehydration, refrigeration, freezing, etc

3

What is decontamination

Treatment of objects, surfaces, etc to make them clean and safe to handle

4

What is disinfection

Removal of all active pathogens, but not necessarily all microorganisms and not spores (dormant and not active)

5

What is widely used for killing microbes and why

Heat - high temperatures denatures macromolecules and DNA, which kills microbes

6

What is the decimal reduction time

The amount of time required to reduce viability tenfold, is determine in relation to the temperature and growth conditions

7

What can survive heat

Endospores and other types of spores can survive heat treatment that would normally kill vegetative cells

8

What is an autoclave

A device that uses steam under presure to produce 121C at 15 PSI, allows the termpature of water to get above 100C without evaporating

9

What are autoclaves used for

Used to sterilize both liquids and dry items

10

How long does it take to sterilize small volumes

About 15 minutes, it takes larger volumes more time because it takes longer to heat up large amounts

11

What is pasteurization

Precisely controlled heat and time to reduce the microbial load in heat-sensitive liquids, such as milk. It kills all pathogens in the product but does NOT kill all the normal microorganisms. It avoids the altering of product quality

12

What is used in radiation sterilization

Microwaves, UV, X-rays, gamma rays, and electrons can kill microbes. Exposing microbes to high enough energy can damage them to death

13

What is UV useful for

UV is useful for decontamination of surfaces because it can't penetrate solid, opaque, or light-absorbing material

14

What is ionizing radiation

High energy electromagnetic radiation that produce ions and other reactive molecules that damage cell components, some microorganisms can be more resistant to this than others

15

What is filter filtration

Filtration avoids the use of heat on sensitive liquids and gases. The pores of filter are too small for organisms to pass through

16

What are depth filters

HEPA filters

17

What are membrane filters

Function more like a seive

18

What are the 3 possible antimicrobial agents

Bacteriostatic, bacteriocidal, and bacteriolytic

19

What is bacteriostatic

After adding the agent, the number of cells and number of viable cells have stopped increasing and is leveling off. They are still alive just not growing anymore

20

What is bacteriocidal

The cells are killed after the agent is added and the number of viable cells decrease while the number of cells stops increasing

21

What is bacteriolytic

An agent that will cause the cells to break apart (penicillin) as the cells grow. The cells will burst leading to the decline of the number of cells as well as the number of viable cells

22

What is minimum inhibitory concentration

MIC - is the smallest amount of an agent needed to inhibit growth of a microorganisms. It varies with the organism and its numbers as well as the abiotic factors such as temp, pH, and medium

23

Describe a disc diffusion assay

A antimicrobial agent is added to filter paper disc, which is then placed on a petri plate inoculated with a lawn of the test bacteria. The MIC is reached at some distance from the disc

24

What is the zone of inhibition

The area of no growth of the test bacteria around the disc, this zone can be measured and compared. Larger zone of inhibition means its more effective

25

Describe the antibiotic dilution series

Useful for determining the MIC. Have a set of tubes with broth that bacteria can grow in. Perform a series of serial dilutions of the antibiotic and putting dilutions in the broth. The first tube to show no microbial growth is most likely the dlution of MIC

26

What are the two categories of chemical antimicrobial agents

Products used to control microorganisms in industrial applications and products designed to prevent growth of human pathogens in inanimate environments and body surfaces

27

What are sterilants

Kills all microbes

28

What are disinfectants

Kills most microbes but not all and not spores

29

What are sanitizers

Reduce microbe levels considered safe

30

What are antiseptics

Kill or inhibit microbes without harming the host

31

What are important antiseptics

Alcohol, Phenol-containing compounds, Cationic detergents, Hydrogen peroxide, and Octenidine

32

What does penicillin affect

Cell wall synthesis

33

What is cirpoflaxin affect

DNA gyrase, is important because bacteria have it but humans don't

34

What is erythromycin affect

Ribosomal 50s subunit

35

What do tetracyclines and streptomycins affect

Ribosomal 30s subunit

36

What is selective toxicity

The ability to inhibit or kill a pathogen without affecting the host

37

What are growth factor analogs

Are structurally similar to growth factors but are not functional. Can disrupt cell metabolism

38

What are antibiotics

Naturally produced antimicrobial agents but less than 1% of antibiotics are clinically useful

39

What are semisynthetic antibiotics

Antibiotics that have been modified

40

What is the broad spectrum of antibiotics

Different bacteria vary in their sensitivity to antibiotics

41

What are B-lactam antibiotics

They consist of over half of all antibiotics used worldwide. Includes penicillins and cephalosporins

42

What is penicillin

Produced by fungi. Is primarily effective against G+ bacteria. It targets cell wall syntehsis by inhibiting transpeptidation by biding to transpeptidase enzymes

43

What are aminoglycosides

They contain amino sugars bonded by glycosidic linkages

44

What are some examples of (streptomyces) aminoglycosides. Streptomyces makes several antibiotics

Kanamycin, neomycin, and streptomycin

45

What do aminoglycosides target in bacteria

They target the 30s ribosomal subunit to inhibit protein synthesis

46

Why are they aminoglycosides no longer used today

Neurotxicity and nephrotoxicity

47

What are macrolides

Broad-spectrum of antibiotic that targets the 50s ribosomal subunit of ribosome Ex. Erythromycin

48

What are tetracyclines

Broad-spectrum inhibitom of protein synthesis by inhibiting the function of 30s ribosomal subunit of ribosome

49

What is antimicrobial drug resistance

The acquired ability to resist the effects of a chemotherapeutic agent, can result from the mutation of bacterial gene

50

What is an example of a mutation that could lead to antimicrobial drug resistance

A mutation that encodes for the ribosomal protein that alters the antibiotic binding site without altering the protein's function. Can also result from acquiring a foreign gene

51

What are the 6 reasons that microorganisms can be resistant to certain antibiotics

1. WT lacks target that the antibiotic inhibits
2. WT is impermeable to antibiotic
3. Evolve change in the target of the antibiotic (mutation to produce resistance)
4. Evolve a resistant biochemical pathway (bypass targeted pathway
5. Acquired gene to inactivate or degrade the antibiotic
6. Acquire gene to pump out the antibiotic

52

Describe antibiotic inactivation by modification or cleavage

Antibiotics can have certain functional groups attacked that render it inactive

53

Where are drug-resistance genes located

On the R plasmid or sometimes on transposon that jumped into the R plasmid

54

Where do R plasmids originate

R plasmids predate the human use of antibiotics, originally evolved in soil bacteria and were used as a defense against bacteria and fungi that produce antibiotics

55

What happens when antibiotics are overused

The wide-spread use of antibiotics selects for the evolution and spread of R plasmids.

56

How do you minimize resistance to antibiotics in bacteria

By using antibiotics correctly and only when needed

57

What can happen to the R plasmid over time in a population

Resistance to an antibiotic can be lost in a population if the antibiotic is not used for several years, carrying an unnecessary plasmid or gene is a burden and selected against

58

What is bacteriophage therapy

The use of bacteriophage to kill pathogenic bacteria

59

What are sulfa drugs

Inhibit synthesis of folic acid

60

What are nucleic acid base analogs

Formed by addition of bromine or fluorine, block nucleic acid synthesis

61

What are quinolones

Interfere with DNA gyrase. Ex. ciproflaxin