Mim - Lecture 15

Front 1

15.1

King Phillip Came Over From Germany Singing

Back 1

Kingdom, Phylum, Class, Order, Family, Genus, Species

Front 2

15.2

Clones

Back 2

- strains/isolates of each bacteria
- cell growth that are genetically identical
- certain clones are more virulent than others

Front 3

15.3

colonial characteristics

Back 3

the way they appear when grown on agar

Front 4

15.4

mesophiles

Back 4

bacterias that have an optimal temp range for survival b/w 28 and 45C.

Front 5

15.5

aciduricity

Back 5

ability to survive in low pH environments such as stomach and vagina

Front 6

15.6

obligate aerobes

Back 6

completely dependent on the presence of O2 and cannot grow without it

Front 7

15.7

microaerophiles

Back 7

require O2 at about 0.2 Atm (4%). re inhibited, but not killed by higher O2 levels

Front 8

15.8

Capnophiles

Back 8

grow best in elevated CO2 (5-10%)

Front 9

15.9

facultative anaerobes

Back 9

- grow in the presence and absence of O2. Usually prefer growth in O2 because respiration yields 38 moles ATP/mole glucose. Fermentation yields only 2-3 moles ATP

Front 10

15.10

obligate anaerobes

Back 10

cannot grow in the presence of O2. Reasons remain unclear. Some anaerobes are 'aerotolerant'
- cause infections in humans

Front 11

15.11

enzymes to detoxify potent oxygen radicals

Back 11

- SOD
- catalase
- peroxidase
- cytochrome oxidase

Front 12

15.12

prototrophs

Back 12

synthesize their own vitamins

Front 13

15.13

auxotrophs

Back 13

require exogenous source of vitamins

Front 14

15.14

autotroph (lithotroph)

Back 14

use CO2

Front 15

15.15

heterotroph (organotroph)

Back 15

use organic carbon

Front 16

15.16

nitrogen source

Back 16

usually NO2- reduction but may be N2 fixation and reduction
- in media hydrolysates of animal and plant tissues are used as organic sources of nitrogen

Front 17

15.17

Sorbitol

Back 17

carbon sugar source

Front 18

15.18

MacConley Agar

Back 18

- medium designed to grow Gram-negative
- stain lactose fermentation.
- contains bile salts (to inhibit most Gram-positive, except Enterococcus and Staphylococcus),
- crystal violet dye (inhibits Gram-positive),
- neutral red dye (stains microbes fermenting lactose),
- lactose and peptone.

Front 19

15.19

colors of MacConley Agar

Back 19

- utilizing the lactose in the medium, Lac+ bacteria such as Escherichia coli, Enterobacter and Klebsiella will produce acid, which lowers the pH of the agar below 6.8 and results in the appearance of red/pink colonies.
- Non-Lactose fermenting bacteria such as Salmonella, Proteus species and Shigella cannot utilize lactose, and will use peptone instead. This forms ammonia, which raises the pH of the agar, and leads to the formation of white/colorless colonies.

Front 20

15.20

liquid media

Back 20

- useful for growing monocultures (pure cultures from body sites that are normally sterile, blood, CSF etc)

Front 21

5.21

solid media

Back 21

- used to separate mixed populations of bacteria from sites that harbor a resident microbiota or where the clinical specimen may be contaminated by resident bacteria, skin, mucosa, feces etc

Front 22

5.22

streaking

Back 22

- for isolation via dilution

Front 23

5.23

goal of collecting specimens:

Back 23

- obtain pure culture of causative bacterium
- method of collection dependent on where the specimen is from

Front 24

5.24

Gen. purpose media:

Back 24

- highly nutritious
- blood and chocolate agar

Front 25

5.25

blood agar

Back 25

- 5% sheep RBc
- add RBC at low temp to keep them intact
- indicator medium

Front 26

5.26

chocolate agar

Back 26

- 5% sheep RBC
- most nutritious
- RBCs added at high temp where cells are lysed
- nutrients directly available
- influenza

Front 27

5.27

alpha hemolysis

Back 27

- incomplete, grenning, hemolysis, change in color
- caused by the release of peroxides by bacteria
- RBC intact

Front 28

5.28

beta hemolysis

Back 28

- complete
- cytotoxins destory a whole area of RBC -> when plate is held up to light, you can see thru it

Front 29

5.29

differential selective media

Back 29

- capable of isolating certain categories of bacteria
- or to differentiate species

Front 30

5.30

manitol-salt agar

Back 30

- one type of differential medium
- contains high levels of NaCl
- carbon source = mannitol
- pH indicator = Phenol Red
- used to isolate species of bacteria that can survive at high levels of salt such as bacteria from the skin

Front 31

5.31

growth of mannitol fermenting bacteria

Back 31

- results in a pH drop and change of the indicator from red to yellow

Front 32

5.32

Eosin Methylene Blue (EMB)

Back 32

- differential and partly selective medium
- adapt at isolating bacteria from the gut (the Enterobacteriacae)
- contains lactose as the carbon source, and eosin and methylene blue dyes as inhibitors of gram-positive bacteria.
- if colony can't metabolize lactose: remain colorless = pathogen
- if colony = colored = normal member of gut microbiota

Front 33

5.33

differential utilization of sugars:

Back 33

- can be used to identify a number of bacteria
- MacConkey Agar: sorbital can be added instead of lactose. bacteria that can metabolize sorbitol will have a pink color, non-sorbitol fermenters will be colorless

Front 34

5.34

selective media

Back 34

- designed exclusively to isolate one particular type of microorganism.
- anti-fungal and antiobiotics can be included in the media

Front 35

5.35

Thayer-Martin (TM) agar

Back 35

- for isolating the gonorrhea-causing pathogen Neisseria.
- TM is a modified chocolate agar that suppresses the growth of all bacteria except Neisseria gonorrhoeae and N. meningitides