Production of capsular polysaccharide does not influence Staphylococcus aureusvancomycin susceptibility

BMC Microbiology

Research Article

Jean C Lee¹  Andrea Jansen²  Christiane Szekat²  Gabriele Bierbaum²  Michael Türck²  Christiane Wolz³  Wiebke Schröder³  Christiane Goerke³ 

[1] Channing Laboratory, Brigham and Women’s Hospital, Harvard Medical School, 02115, Boston, USA;Institut für Medizinische Mikrobiologie, Immunologie und Parasitologie, Universitätsklinikum Bonn, Sigmund-Freud-Str. 25, D-53105, Bonn, Germany;Interfakultäres Institut für Mikrobiologie und Infektionsmedizin, Universität Tübingen, D-72076, Tübingen, Germany;

关键词: Vancomycin;    Brain Heart Infusion;    Vancomycin Resistance;    Mueller Hinton;    Brain Heart Infusion Medium;   

DOI  :  10.1186/1471-2180-13-65

 received in 2013-01-18, accepted in 2013-03-04,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundDiverse mechanisms (increased cell wall thickness, low cross linking, decreased autolysis, etc.) have been reported for Staphylococcus aureus strains with intermediate vancomycin susceptibility (VISA). This study was conducted to identify common mechanisms responsible for decreased vancomycin susceptibility in a VISA strain pair.ResultsTranscriptional profiling of the clinical heterogeneous VISA isolate SA137/93A and its spontaneous homogeneous mutant strain SA137/93G pointed to an increased capsule production in the strain pair compared to a susceptible control. Furthermore, transcript quantification of the gene cap5E, which is essential for capsule biosynthesis, revealed elevated levels in the VISA strains SA137/93A, SA137/93G and Mu50 in comparison with susceptible strains Reynolds, Newman and SA1450/94. The increased expression was observed in bacteria from exponential as well as stationary growth phase. However, suppression of type 5 capsule formation by expression of antisense RNA did not increase vancomycin susceptibility in the VISA strain SA137/93G. Likewise, construction of inducible mutants of S. aureus Newman or repair of capsule biosynthesis of S. aureus HG001 and S. aureus 1450/94 did not influence resistance to vancomycin. Furthermore, purified type 5 polysaccharide did not protect indicator strains from the action of vancomycin.ConclusionsThe VISA strain tested in this study displayed an increased production of type 5 capsular polysaccharide. However, the production of capsule material did not protect strain SA137/93G and three vancomycin sensitive strains in the presence of vancomycin and thus is not part of the resistance mechanism; however it may represent a by-product of VISA life style that is often characterized by a high sigma factor B activity.

【 授权许可】

Unknown   
© Jansen et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.