Characterisation of antibiotic resistance in Streptococcus, Enterococcus and Staphylococcus using a bioinformatics approach.
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Date
2005
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Abstract
The rate at which bacterial pathogens are becoming resistant to antibiotics is quite alarming,
and therefore much attention has been focussed on this area. The mechanism whereby the
bacterial cells acquire resistance is studied in order to determine how this process works as
well as to determine if any future resistance mechanisms can be circumvented. In this study
three different genera and the antibiotics that are resistant to them were used, namely,
penicillin resistant Streptococcus, vancomycin resistant Enterococcus and methicillin resistant
Staphylococcus. The results prove that the active sites SXXK, SXN and KT(S) G in the
penicillin resistance Streptococcus plays a major role in resistance. It is seen in this study that
the SXXK active site is found in all the resistant and most of the intermediate strains, therefore
proving to be an important component of the cell wall resistance. It was subsequently noticed
the greater the number of mutations found in the sequences the higher the resistance. Three
dimensional structures showed the actives sites and their binding pockets. The results also
show the change in conformation with a mutation in the active site. The results also proved
that the Penicillin Binding Protein (PBP) genes essential for resistance are PBP Ia, PBP 2b
and PBP 2x. The results obtained, for the vancomycin resistance in Enterococcus study,
proved that the VanC and VanE cluster are very much alike and VanE could have evolved
from VanC. There is also close similarity between the different ligase genes. The VanX 3D
structure shows the position of the critical amino acids responsible for the breakdown of the
D-Ala-D-Ala precursors, and the VanA ligase 3D structure shows the amino acids responsible
the ligation of the D-Ala-D-Lac precursors. The analysis performed on the methicillin
resistance in Staphylococcus study showed that the genes used to confer resistance are very
similar between different strains as well as different species.
Description
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
Keywords
Drug Resistance In Microorganisms--Genetic Aspects., Pathogenic Bacteria., Streptococcus., Enterococcus., Staphylococcus., Antibiotics., Vancomycin Resistance., Methicillin Resistance., Penicillin., Theses--Genetics.