NTU Undergraduates' research April 2014 - Biosciences | Seite 66

Akruti Dhanani N0254909

Hypermutator Strains of Escherichia Coli MG1655
Abstract:
Hypermutator strains of Escherichia coli have been proven to acquire mutations on the spot, therefore,
posing a threat to the duration of treatment in patients. This produces new mutant generations in
patients with resistant parent strains. Therefore, the primary aim of this study was to isolate
hypermutator strains of E.coli, and determine the mutations on the rpoB gene, caused by the
antibiotics. Hypermutator strains of Escherichia coli MG1655 were isolated using antimicrobial
susceptibility. Rifampicin, streptomycin and ciprofloxacin were used at different concentrations and
growth media, such to aid and identify mutant strains resistant to each of these antibiotics. Selection of
rifampicin, streptomycin and ciprofloxacin at 4×MIC and 2×MIC for the latter two. These were the
concentrations where the antibiotics were expected to target the rpoB, strA-strB or aadA and GryA
genes respectively. Mutant strains were identified when exposed to rifampicin and streptomycin twice.
Exposure to ciprofloxacin at 2