Bovine Milk

Question 1

steps for CMT

Answer 1

• prestrip the teats into the strainer and check for any obvious mastitis like chunks or discoloration
• use teat dip on each teat
• wipe excess with a towel
• stand to the left of the cow and hold the paddle handle towards the head as you collect from each teat
• pour excess milk and make sure there are 2mls in each (there is a line to mark this)
• 1 pump CMT reagent into each well
• swirl to mix
• record results
• post dip on each teat

Question 2

steps for milk culture

Answer 2

• prestrip each teat into the strainer thing and discard
• use predip on each teat
• dry each teat with paper towel
• use alcohol soaked gauze to wipe all four teats starting from far to near, standing on the left side of the cow, right back, right front, left front, left back
• open the sterile vial and collect milk with vial held at a 45 degree angle gonig from near to far, left back, left front, right front, right back
• recap the vial and label it with animal ID and date
• use post dip on all four teats

Question 3

name what bacteria each of the following plates select for:
- blood agar
- MacConkey
- Mannitol salts
- edwards

Answer 3

blood agar: gram + (staph and strep)
MacConkey: gram - (E coli or Klebsiella)
Mannitol salts: staph only, yellow for staph aureus
Edwards: strep only

Question 4

which agar types are these?
which bacteria is this and WHY?

Answer 4

starting at top left and going counterclockwise 1-4, blood agar, mannitol, edwards, MacConkey

this is staph aureus: blood agar is +, so we know it is gram +, mannitol selects for staph and it’s positive, it’s also yellow, so we know this is staph aureus. Edwards and MacConkey are both negative.

Question 5

name the agar types and identify what bacteria this is

Answer 5

blood agar, mannitol, edwards, maconkey

this is staph (not aureus), the blood agar is positive so we know it is gram +, the mannitol salts select for staph and it’s positive, but it is NOT yellow so this is not aureus, it is another species. edwards and macconkey are both negative

Question 6

name the agar types and what bacteria this is and WHY

Answer 6

blood agar, mannitol, edwards, macconkey
this is E coli. blood agar is neg which means it is gram neg, mannitol salts is neg which means it is not staph, edwards is negative which means it is not strep, and Macconkey is positive, which means the bacteria is gram neg, and looks very pink which means it is E coli

Question 7

name the agar types and name the bacteria

Answer 7

blood agar, mannitol, edwards, macconkey

blood agar is negative, so it is not a gram positive, mannitol is neg, so it is not a staph, edwards is neg, so it is not a strep, and macconkey is positive and looks more pale, so it is klebsiella

Question 8

name the agar types and what bacteria this is and WHY

Answer 8

blood agar, mannitol, edwards, macconkey
blood agar is positive, so it’s a gram positive bacteria, mannitol is neg so it’s not a staph, edwards is positive so it’s a strep, macconkey is neg so it’s not a gram neg. on the edwards colonies, it looks slightly more yellow ish, so this is strep uberis

Question 9

name the agar types and the bacteria this is and WHY

Answer 9

blood agar, mannitol, edwards, macconkey

the blood agar is positive, so it is gram +, mannitol is negative so it’s not staph, edwards is positive so it’s a strep, and there’s blue ish colonies which means it is strep agalactiae, macconkey is neg so it is not gram negative

Question 10

steps for proper plate streaking

Answer 10

• disinfect the area and your hands, make sure you are wearing gloves
• label the plate with the sample ID and the date, your name
• to get the sample with the first loop, hold the tube at an angle
• hold the lid at an angle over top of the plate with knuckles of non dominant hand
• make one streak with the first loop
• get a second loop and make your 2nd streak, flip the loop over and do a 3rd streak
• get a 3rd loop and do one final 4th streak, make sure to tke up the entire plate!