Experiment -- The Staphylococci
Materials
- Mannitol Salt Agar (MSA) Plates -- 3 per group of
2
- Blood Agar Plates (BAP) -- 3 per group of
2
- Rabbit Plasma for Coagulase Test
- Hydrogen Peroxide for Catalase Test
Cultures
- Staphylococcus
aureus
- Staphylococcus
epidermidis
- Staphylococcus
saprophyticus
Activities
Day 1
- Gram stain each of the organisms
- Streak each organism on MSA and BAP. Streak for
isolation.
Day 2
- Observe hemolysis on the BAP's.
- Observe for salt tolerance and mannitol
fermentation on the MSA plates.
- Are salt tolerance and mannitol fermentation
the same thing?
- How do you detect salt tolerance on an MSA plate?
- How do you detect mannitol fermentation on an MSA plate?
- Perform the slide coagulase test:
- Put a drop of water on a clean slide with a
loop
- Emulsify a loopful of bacteria in this drop
until smooth. Take the organism from the BAP not the MSA
plate.
- Add a drop of plasma with a loop, mix well and
rock the slide gently. In a positive test, visible clumps will
become apparent within a couple of minutes.
- Discard in the contaminated discard
container.
- Perform the slide catalase test:
- Smear a loopful of bacteria onto a clean
microscope slide.
- Add a small drop of
H2O2
to the smeared organism with a dropper.
- A positive test will begin to bubble within a
few seconds. Don't get too close to the aerosol!
- Discard in the contaminated discard container.
Decontaminate the bench top!