3 antibiotic dicks
| Distilled water
| Culture of Serratia marcesans
| Sterile filter-paper disks
| Transparent tape
| 1 sterile nutrient agar plate
| Metric ruler
| 1 sterile cotton swab
| Lab apron
In the Antibiotic Resistant Bacteria lab, the effect of different antibiotics on the zone of inhibition on bacteria, Serratia marcesans, was measured in millimeters. The safety equipment, lab apron and goggles were worn at all times by the scientist to ensure lab safety precautions.
First, four quadrants were made with Sharpie on the bottom of the nutrient agar plate, to tell the four disks apart later on. When the agar plate is sectioned, a cotton swab of Serratia marcesans must be carefully swiped gently, all over the top of the nutrient inside the plate. The plate must be evenly swabbed like coloring a coloring book to ensure readable results after the antibiotics are tested. The cotton swab is disposed of carefully in the designated waste bag to avoid contamination after use.
After the nutrient agar plate is spread with Serratia marcesans, forceps are used to take one of each antibiotic disk and place in the center of the designated section of the plate. Chloramphenicol, Kanamycin, Tetracycline, and a blank antibiotic disk were each placed into a section of the agar. The nutrient agar plate was then sealed with transparent tape for a secure closure before being placed into an incubator, upside down, at room temperature for 48 hours.
Finally, the agar plate is observed after 48 hours in the incubator. Data is recorded for each antibiotic by measuring, in millimeters, the cloudy space from the antibiotic disk, out. After data is recorded, the nutrient agar plate will be collected for safe disposal. Hands must be washed thoroughly with soap after handling bacteria samples.
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