Student Number : 0418251N -
MSc research report -
School of Molecular and Cell Biology -
Faculty of Science / Rifampicin is a chemotherapeutic agent used to combat mycobacterial and nocardial
infections. Four enzymatic inactivation mechanisms have been identified which are
partially responsible for the increasing number of rifampicin resistant strains. These are
ADP-ribosylation, phosphorylation, decomposition and glucosylation. The gene encoding
the latter, rgt, has been cloned and characterized from the opportunistic pathogen
Nocardia brasiliensis. However, as of yet nothing is known of these inactivation
enzymes. Thus in order to study the properties of the mechanism it is necessary to
observe structure-function relationships through the characterization of mutants.
Furthermore, the rgt gene confers a small yet reproducible increase to the vancomycin
MIC. This has indicated that there may be other enzymatic mechanisms which are
involved in the inactivation of vancomycin. Vancomycin is an important antibiotic as it is
used to treat gram-positive infections by multi-drug resistant strains. Hitherto, no
mechanisms of enzymatic inactivation have been identified for vancomycin. Thus in
order to identify regions of DNA which may play a role in the high level resistance to
vancomycin as observed in N. brasiliensis it was necessary to screen a genomic library of
this organism. This was performed in a gram-positive background. No clones were
identified in this study that had an increased resistance to vancomycin, indicating that the
DNA involved in the phenotype is greater than that of the average insert size of the
library, 1.9 kb.
Future work will thus involve the generation of a genomic library with larger fragments
and the subsequent screening of this. Additionally, performing a mutational analysis on
the rgt gene may provide further insight into the specifics of the inactivation enzymes and
thus will contribute to combating infection by opportunistic and other pathogens.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/1784 |
| Date | 16 November 2006 |
| Creators | Baker, Alison Saxe |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 525780 bytes, 63227 bytes, application/pdf, application/pdf, application/pdf, application/pdf |
Page generated in 0.0015 seconds