Antimicrobial Lab Report

1105 WordsDec 1, 20115 Pages
Introduction: Chemical methods of control: Antimicrobial drugs, involves the use of chemicals to prevent and treat infectious diseases. Pasteur and others observed that infecting an animal with Pseudomonas aeruginosa protected the animal against Bacillus anthracis. Later, the word “antibiosis” (against life) for this inhibition and called the inhibiting substance “Antibiotic”. As researchers found out more and more about these chemicals they were able to discover that antibiotics are chemicals or natural substances such as bacteria, fungi, as well as synthetic drugs; that inhibit or kill microbes in small amounts. Chemotherapeutic agents are antimicrobial chemicals (natural or synthetic) that can be used internally or may be absorbed.…show more content…
Make sure to sterilize the loop between each disk placement. To do this, dip into alcohol and then hold it over the Bunsen burner flame for at least ten seconds. To secure its place onto the agar, tap the disk lightly into the agar. The inverted plate is then incubated at 35 degrees Celsius for 48 hours. This was done three more times with the remaining broth cultures. The results are measured in diameters of the zones in millimeters. Record the zone size and using Table 1, indicate whether the organism is Susceptible, intermediate, or resistant. Results: Antimicrobial Agent Disk Code Escherichia coli Zone Size / S, I, or R Penicillin P-10 0 /R Bacitracin B-10 0 /R Streptomycin S-10 0 / R Tetracycline T-10 18 / I Blank -- 0 / R Table 2.0: Results of Kirby-Bauer test R = resistant; I = intermediate; S = Susceptible Results for Escherichia coli: Penicillin (P-10) was measured at 0mm in diameters. There was no susceptibility. Therefore, with the zone size as 0, Escherichia coli was resistant to penicillin. Tetracycline (T-10) was only one measured at 18mm in diameter. This zone size falls in the category of Escherichia coli having an intermediate resistancy (Table 1) to the antimicrobial agent. **The only one that had any effect! Bacitracin (B-10) was measured at 0mm in diameters. There was no susceptibility. Therefore, with the zone size as 0, Escherichia coli was resistant to bacitracin Streptomycin
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