Making Blood Agar Plates
Laura Sycuro, Ramon Cortez, Shae Konschuh
Disclaimer
DISCLAIMER – FOR INFORMATIONAL PURPOSES ONLY; USE AT YOUR OWN RISK
The protocol content here is for informational purposes only and does not constitute legal, medical, clinical, or safety advice, or otherwise; content added to protocols.io is not peer reviewed and may not have undergone a formal approval of any kind. Information presented in this protocol should not substitute for independent professional judgment, advice, diagnosis, or treatment. Any action you take or refrain from taking using or relying upon the information presented here is strictly at your own risk. You agree that neither the Company nor any of the authors, contributors, administrators, or anyone else associated with protocols.io, can be held responsible for your use of the information contained in or linked to this protocol or any of our Sites/Apps and Services.
Abstract
Purpose
Blood agar is agar base enriched with 5% blood. It is an enriched medium often used to grow fastidious organisms and to differentiate bacteria based on their hemolytic properties.
Key concepts
The agar base can vary – Brucella is what is generally prefered for the growth of diverse vaginal organisms, but Casman and Columbia have also been used and shown to support a broad variety of organisms.
Steps
Preparation
Mix appropriate amount of agar base into distilled water in a glass media bottle.
500mLagar in a 1 L bottle makes ~25 plates.- Each bottle of powdered media lists the grams of powdered media needed for 1 L of media. Use half this amount for 500 mL.
Stir media with stir bar until completely dissolved.
Autoclave
- For 1 or 2 bottles of Brucella agar media, autoclave for 15 minutes.
- For 3 or more bottles of Brucella agar media, autoclave for 30 minutes.
- For Columbia agar media, autoclave for 45 minutes.
Note
**Be sure to label the bottle and the autoclavable pan with 'Agar' and requested autoclave time ('15 minutes'). Also can be helpful if you add ~1 inch of water to the bottom of the pan (they won't always do this for you).
After dropping off downstairs for autoclaving, turn water bath on and set to 55°C . Remove blood from refrigerator and allow to warm on the bench.
- Check and make sure no one else needs water bath at lower temperature for the next 1-2 hours.
- Use the freshest blood available and generally do not use blood that is over 1 month old.
Pouring
Pick up media from downstairs shortly after run completes (they should place it in a 55°C incubator downstairs after the run).
- Place in
55°Cwater bath for 20-30 minutes. - Media is ready to pour when bottle is warm, but not hot to the touch.
Mix blood (at room temperature) by gently swirling (rubbing the bottle between your hands works well).
Prepare plates and pouring area.
- Clear and clean area of bench near Bunsen burner.
- Arrange sterile plates right side up in small stacks of 4-5.
- Stripe plates if desired.
Bring blood, a 25mL serological pipet, and the serological pipettor to the media making area (stir plate).
Remove 1 bottle of media from water bath and place on stir plate.
While media is being stirred, pipet 25mL of blood into 500mL of media (final concentration of5% (v/v))
Stir for 1 minute or until mixed.
Move to pouring area and pour plates immediately.
- Flame lip of bottle at the start of each stack of plates.
- When bottle is empty, carefully flame plates to remove bubbles.
Gently push plates to back of bench (away from Bunsen burner hose) to solidify and then clean up bench and rinse the media bottle.
- All papers and pipets with blood on them get disposed in the yellow biohazard waste bin (near fume hood).
Prepare to pour second batch of plates if needed.
Completely finish with one batch of plates before removing a second bottle from water bath.
- Do not add blood to second bottle and then put back into water bath – carry out the pouring procedure from start to finish 1 bottle at a time.
