fairfolio
Saved Projects

Determining Which Antibiotic Is Most Likely to Prevent Resistance by Effectively Killing Bacteria

CSEF · 2012 Microbiology (General)

Erika R. Witt · Tamalpais High School, Mill Valley, Marin County

Overview

Objectives/Goals In the past, bacterial infections were deadly, but today they can be treated with antibiotics. Bacteria can mutate and become resistant to the antibiotics used to treat them, and these strains can be lethal. The purpose of my experiment was to find the antibiotic most likely to kill and least likely to leave inhibited bacteria, reducing the chance of mutation and resistance. Methods/Materials Three antibiotics were tested against Escherichia coli bacteria; Cefazolin, Ofloxacin and Gentamicin. Test tubes containing bacteria and media with seven different concentrations of each antibiotic were incubated and monitored for growth. The concentrations without visible growth were then sub-cultured to determine which concentrations only inhibited the bacteria (Mean Inhibitory Concentration, [MIC]), and which concentrations killed them (Mean Bactericidal Concentration [MBC]). I monitored the growth of the bacteria to see if there was a difference between the MIC and the MBC of each antibiotic.The fewest dilutions between the two concentrations showed which antibiotic killed most effectively, without permitting time for bacteria to mutate. Results The antibiotic Cefazolin had no identifiable MBC. Ofloxacin had three dilutions between the MIC and the MIC, and Gentamicin's MIC was the same as its MBC Conclusions/Discussion In conclusion, Gentamicin was the best antibiotic for treating E. coli because the MIC was the same as its MBC, and therefore left no chance for inhibited bacteria to become resistant. In contrast Ofloxacin had a range of dilutions between the MIC and MBC, potentially enabling it to continue growing and select for resistance. Cefazolin never reached an MBC, meaning it cannot kill bacteria at a concentration tested, and therefore leaves a greater chance for bacteria to continue growing and develop resistance.

Summary statement

My project focused on determining which antibiotic was most effective and most likely to prevent the development of resistant bacteria.

Help received

My father, an infectious disease doctor, helped me obtain materials and supervised my techniques and the safety of the project.

Competition history

  • CSEF 2012 Microbiology (General) · Entry S1526

Resources

Related projects

Closest projects by meaning, across every fair and year in the corpus.

Browse more like this

Source: California Science & Engineering Fair public projects

Save projects to your library

Sign in with Google to keep track of projects you find interesting, organized into folders. An account also raises your daily allowance for “Has this been done?”, and lets you create a key for the MCP server with a much higher limit than anonymous use. Browsing stays public.

Continue with Google