agars and broths

Question 1

theyer martin agar

Answer 1

neisseria

Question 2

Levine Agar/EMB

Answer 2

E.coli produces metallic green sheen on EMB.
selective for gram - species

high lactose fermentation - black
lowe lactose - pink

Question 3

Desoxycholate Agar

Answer 3

To isolate and differentiate between various members of the family Enterobacteriaceae.
DOC contains sodium deoxycholate and citrate which work to inhibit the growth of Gram-positive organisms.
The medium also contains the sugar lactose, which serves to differentiate among enterics that ferment and do not ferment lactose.
Fermentation of lactose appears as a red color due to the pH indicator neutral red, which is included in the medium.
Neutral red is colorless above pH 6.8 and red below 6.8.

Question 4

macconkey agar colours

Answer 4

pink- lactose postive

colourless - negative

Question 5

kliegelers iron agar

Answer 5

used for screening of gram - agar
colours red and yellow
red- negative
yellow - postive

Question 6

e.coli on kliegers agar

Answer 6

slant yellow
but yellow
no black - no h2s
but there is gas produced

Question 7

difference between e.coli salmonella and shiegella on kleigers agar

Answer 7

e.coli ferment both sugars lactose and glucose but salmonella only ferment glucose and produce gas

salmonella: red slant
yelllow but
black colour

shiegella :
the same as salmonella but no hydrogen sulfate produced
Do not produce H2S
Do not produce gas from glucose
non motile compared to salmonella

Question 8

lowinstein jensen broth

Answer 8

for the primary isolation of TB
20 hours generation time unlike most bacteria which is 20 mins so these bacteria grow slowly
4-8 weeks you will see colonies

Question 9

chocolate agar

Answer 9

prepared by heating blood until colour change which releases both blood factors 10 (Hematin) and 5 (NAD)- which are required for the growth o fmost stains of H.influenza and neisseria

Question 10

alpha strep and the test we use to distinguish them

Answer 10

s.pneumonia and s.virdans to distinguish them, s.pneumonia is sensitive to optochin wherease virdans which is a normal streptococci in our bodies is not