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Prepared by James Sams
© Fall 2005 All rights reserved.
For use with Professor Dick’s Microbiology Class, PHCC.
- What is Growth Media?
- Growth media is any substance that is used to cultivate a specimen. Examples would be the different types of agar,
broths, etc.
- How does one obtain a specimen?
- A specimen is obtained via different procedures. These include:
- The use of a swab. This is used to obtain samples that are located on irregular surfaces such as a mouth, a wall, a
doorknob, etc. - When a master culture is available, one can use a loop or a needle for obtaining a sample.
- The loop is used to obtain a sample and to inoculate a petri dish, agar slant, or a broth.
- The needle is used to inoculate different media that require the stab technique to be performed.
- OK, now I have obtained my sample. How do I transfer this sample to a growth media for development?
- First, you need to know the proper techniques.
- 1. Flame the loop or needle, or obtain a sterile cotton swab.
- 2. Flame the opening of the master culture glass test tube.
- 3. Flame the opening of the glass test tube containing the growth media.
- 4. Touch the hot flamed loop or needle to the edge of the agar to cool.
- 5. Next, obtain your sample by touching the master culture. (Remember, these are microscopic organisms, a touch is all
you need.) - 6. Transfer your acquired sample to the appropriate growth media, using the technique for that media.
- 7. If using the loop or needle, when finished flame the loop/needle and the opening of the glass test tubes.
- 8. Do not flame a cotton swab, or a petri dish!
- 9. If using a cotton swab, open package, obtain sample. Slightly open the lid to the petri dish and apply the sample using
the zigzag technique, and then dispose of cotton swab in red biohazard bag.
- What technique do I use for the petri dish?
- There are two techniques that we have learned thus far.
- The first is a streak method, which can be seen by clicking here. This is by far a simple technique in which involves a
simple zigzag pattern of inoculation. This is obtained by lightly touching the instrument used to obtain the sample to the
surface of the agar and applying a back and forth motion to spread the sample. - The second is the quadrant method. This uses the same pattern as above, except that one does this pattern in the
quadrants. An example of this method can be seen by clicking here. One starts in one quadrant and streaks the sample.
Flame the loop, then (cool the loop an a piece of the agar at the edge) streak the second quadrant by overlapping the first
streak. Flame the loop, then streak the third quadrant by overlapping the second. Finally, Flame the loop and then streak
the final quadrant by overlapping the third.
- What technique do I use for the agar slant?
- Use the streak method.
- What technique do I use for the broth?
- Obtain your sample, and then swirl the sample in the broth. Yep, it is that simple.
- What technique do I use for the stab tubes?
- Obtain your sample with the needle. Then, take your needle and stab the agar in the tube almost to the bottom, and then
in an up and down motion a couple of times, and then take out the needle. Again, a simple technique.
- Morphology, how do I know?
- Go here and view the animation. This will help you galore with the morphology question.
- Help, what are the parts of the miroscope?
- Go here to see a diagram of the microscope.
- What are the shapes of bacteria?
- Cocci are round, Bacilli are rod shaped, and spirilla are spiral shaped.
- What is the difference between strepto- and staphylo-?
- Strepto- is a chain of bacteria, whereas staphylo- is a cluster.
