Lab final

Question 1

high temperature effect on microbes

Answer 1

impact metabolism, enzymes denature, lipids of membrane destroyed
-microbicidal

Question 2

low temperature effect on microbes

Answer 2

slow cell growth bc chemical rxns are reduced, reduced fluidity of membrane, de crease rate of nutirents crossing into cell
-microbistatic

Question 3

psychrophiles

Answer 3

-5 to 20

Question 4

meophiles

Answer 4

10-50

Question 5

thermophiles

Answer 5

45-80

Question 6

troph

Answer 6

wider temp range

Question 7

disinfectants

Answer 7

cause injuries to cells

Question 8

brief exposure

Answer 8

single hole in the cell membrane
-dilutes difinfectants power
-need many holes to kill the cell

Question 9

How to increase disinfectant effectiveness

Answer 9

-increase concentration of disinfecting agent and increase the amount of time that the chemical is left in contact with the microorganisms

Question 10

hospital disinfectant (has to pass what test)

Answer 10

has to pass the use-dilution test to see how well it works against high microbial load dried on a hard nonporous surface

Question 11

cylinders soaked in

Answer 11

staphylococcus aurerus, salmonella choleraesuis, pseudomonas aeruginosa

Question 12

selective

Answer 12

certain microbes can grow

Question 13

differential

Answer 13

microbes that grow will be a diff color

Question 14

mannitol

Answer 14

-selective and differential, isolate staphylococci
-carbon source: carbohydrate mannitol
-selective agent: NaCl
-phenol red: detects fermentation of mannitol to acidic products

Pink —> yellow (ferments mannitol)

Question 15

MacConkey

Answer 15

-selective and differential
-has bile salt and crystal violent to select for gram (-)
-carbohydrate lactose and PH to detect lactose fermenters vs non fermenters

Pink/purple —> deeper pink (lactose fermenting)

Pink/purple —> yellow (non lactose fermenting)

Question 16

eosin methylene blue agar

Answer 16

-selective for gram (-)
-eosin and methylene blue dyes inhibit the growth of gram (+)
-differential with lactose fermenting bacteria bc they will make a blue-black color that are visible while the non lactose fermenting colonies will be colorless/ amber

Question 17

hektoen

Answer 17

-selective for gram (-)
-shigella and salmonella
-bile salts inhibit gram (+)
-three carbohydrates can distinguish between enteric bacteria
-production of hydrogen sulfide = salmonella NOT shigella

Question 18

TSA

Answer 18

-triple sugar iron agar
-differential medium to see if sugar, glucose or lactoe are fermented
-also detects the production of hydrogen sulfide and gas
-identifies gram (-)

Question 19

oxidase

Answer 19

determines if bacteria has cytochrome C oxidase (enzyme in etc of some bacteria)
-differentiates oxidase (+) pseudomonas from oxidase (-) enterobacteriacaea

Question 20

shortes waves

Answer 20

gamma and x rays
-sterilize heat sensitive objects like plastic but the level of radiation is toxic

Question 21

longer waves

Answer 21

uv light, infared, visible light
-can form free radicals in organisms

Question 22

UVC

Answer 22

for bacteria bc it creates pyrimidine dimers for new covalent bonds between pyrimidines
-mess up DNA helix kills cells if there are enough dimers
-lower energy= safer to work with

Question 23

Kirby bower

Answer 23

higher concentration is closer to the disk
-zone of inhibition is where the microbes cant grow can be measured and used to compare to standard to find if microbe is sensitive or getting resistant
-can help us determine selective toxicity bc other bacteria not pathogen should be unaffected
-also lets us determine therapeutic dose

Question 24

Zone of inhibition

Answer 24

depends on molecular weight of the antimicrobial, type of media, concentration of bacteria culture
-use turbidity

An area of media where bacteria can’t grow due to presence of a drug that impedes their growth

Question 25

kirby bauer standard media

Answer 25

meuller hinton 2

Question 26

tube dilution

Answer 26

takes kirby bower results further to get the minimum dose to kill the bacteria
-MIC