Create a 5 pages page paper that discusses antibiotics and agar diffusion. The agar plate diffusion methods are assays used to observe and quantify the antimicrobial property of tested substances. Bri

Create a 5 pages page paper that discusses antibiotics and agar diffusion. The agar plate diffusion methods are assays used to observe and quantify the antimicrobial property of tested substances. Briefly, the newly inoculated agar is placed with a small piece of paper soaked with the agent. After incubation, antimicrobial substances should produce a sterile ring surrounding the soaked paper. The diameter of the ring is an indication of the strength of the substance’s antimicrobial property. The aim of this experiment was to determine the effects of agar depth, inoculum size, presence of salts, and method of applying antibiotics on inhibition zones.

In determining the effect of agar depth on the result of agar plate diffusion, four plates containing 10 cm3, 20 cm3, 20 cm3, and 30 cm3 agar were first swabbed with Escherichia coli 10418 (1:20 dilution). All plates were oriented horizontally except for the third one, which was slanted. Meanwhile, 2 plates each containing 20 cm3 DSTA were inoculated with 100 µl of either 1:20 E.coli dilution or undiluted broth culture. 4 discs each containing 20 µl 0.5 mg/ml ampicillin were placed in each of the plates. The plates were incubated overnight at 37°C.

For determining the effects of potassium or calcium ions on zone sizes, 0.1 or 1.0 ml of 2M KCl or CaCl2 were added onto their corresponding plates each containing 20 ml DSTA, which would be inoculated with 0.1 ml Pseudomonas aeruginosa (1: 50). 4 discs each with 20 µl of either 20 mg/ml ampicillin (A) or 1 mg/ml streptomycin (S) were then placed on the agar plates. The plates were incubated overnight at 4°C

In observing the difference between two methods of antibiotic application, 8 discs were soaked with 0.5 mg/ml ampicillin, while another 8 were each added with 20 µl of the antibiotic solution. The discs were distributed equally to four DSTA plates inoculated with Staphylococcus aureus.