&
Bacteria
Title: Kirby-Bauer Method of Antibiotic Effectiveness
Purpose: The purpose of this lab was to determine the effectiveness of certain antibiotics and determine their zone of inhibition
Data:
Name of Antibiotic
Zone of inhibition (mm)
Effectiveness
Streptomycin
15mm
Sensitive
Chloramphenicol
29mm
Sensitive
Novobiocin
20mm
Intermediate
Neomycin
13.5mm
Intermediate
Tetracycline
22mm
Sensitive
Analysis:
1. Which antibiotic was the most effective? The most effective antibiotic was Chloramphenicol. Chloramphenicol is used against serious infections such as typhoid fever. This antibiotic produced a zone of inhibition of 29 millimeters. This demonstrates that chloramphenicol is the most effective antibiotic because the bacteria were the most sensitive to it.
2. Will the most effective antibiotic work well for all types of bacteria? Why or why not? Chloramphenicol will not necessarily work well with all types of bacteria. There are millions of bacteria and each has a different characteristic and serves a different purpose. Many bacteria overtime become resistant to the antibiotic and multiply. For example, pseudomonas putida KT2440 is a chloramphenicol-resistant bacterium that is able to grow in the presence of this antibiotic at a concentration of up to 25ml.
3. What are three aseptic techniques you used in this lab activity? Aseptic technique is a procedure used by medical staff to prevent the spread of infection. The goal is to reach an environment that is free of harmful microorganisms. In the lab activity, examples of aseptic techniques used include sterilizing your work area (before and after), “dipping and flaming” the inoculating loop (after every use), and using a sterile disc to add to the center of the plate.
4. Give two reasons why we are seeing an increase in antibiotic resistant bacteria. The dramatic increase in antibiotic resistant bacteria is a result of evolution. Once an antibiotic is used