Essay: Vancomycin Heteroresistance in Staphylococcus aureus

Dirkzwager, M.N. (2016) Essay: Vancomycin Heteroresistance in Staphylococcus aureus. Bachelor's Thesis, Biology.

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Abstract

Bacterial heteroresistance is the presence of small amounts of bacterial cells within a population that have an increased resistance to antibiotics (i.e. an increased MIC). When exposed to an antibiotic these cells have a competitive advantage and are more likely to survive and give rise to a more resistant population. This can be especially problematic in clinical infections, where it is thought to be a cause of treatment failure and has been associated with increased patient mortality. Heteroresistance is seen as an intermediate stage between antibiotic susceptibility and full antibiotic resistance. Amongst the different types of heteroresistances that can occur, heteroresistance against vancomycin by Methicillin-Resistant Staphylococcus aureus (MRSA) is perhaps the most studied. This report aims to create an overview of some of the mechanisms that may lead to vancomycin heteroresistance in this so-called Vancomycin-Intermediate S. aureus (VISA) and to compare these to known mechanisms behind heteroresistance against other antibiotics. It was found that mutations in different regulatory genes are especially common in VISA strains. These mutations affect growth rate, cell wall production and expression of virulence factors. In contrast, heteroresistance to other classes of antibiotics is commonly reported to be caused by mutations in genes encoding single structural proteins. This shows that the mechanisms that lead to an increased antibiotic resistance depend on the mechanism of action of the antibiotic and that there is no 'one' way in which heteroresistance develops. Nonetheless, any type of heteroresistance may develop through improper antibiotic use and the development of heteroresistance can be greatly limited by application of the right antibiotics in high enough doses.

Item Type:	Thesis (Bachelor's Thesis)
Degree programme:	Biology
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	15 Feb 2018 08:10
Last Modified:	15 Feb 2018 08:10
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/13666

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