Ridom SpaServer - Background

Staphylococcus aureus aureus is a major human pathogen causing skin and tissue infections, pneumonia, septicemia, and device-associated infections. The emergence of strains resistant to methicillin (MRSA) and other antibacterial agents has become a major concern, especially in the hospital environment, because of the high mortality of the infections caused by these strains.

Typing of MRSA is used to support infection control measures. Pulsed-field gel electrophoresis (PFGE) is a gold standard for strain typing of MRSA, although it is time-consuming and the inter-laboratory comparability of results requires extensive effort using harmonization of protocols. Therefore, DNA sequence-based approaches are becoming more frequently used because of the ease with which sequence data can be transferred between laboratories via the Internet.

There is evidence for recombination in S. aureus, although it has been shown that point mutations are much more common than recombination events. The result of this was that single locus DNA-sequencing of repeat regions of the coagulase gene (coa) and the Staphylococcus protein A gene (spa) could be used for reliable and accurate typing of MRSA. Spa-typing is especially interesting for rapid typing of MRSA in the hospital setting since it offers a higher resolution than coa-typing.

Despite of being a DNA sequence based method, Staphylococcus protein A gene (spa) typing was hampered by the lack of a consensus on assignments of new spa-repeats and -types. Therefore, in the past spa-typing could not be considered a portable tool. To ensure a uniform code terminology usage we developed the software Ridom StaphType that synchronizes either directly via the http-protocol or file based (e.g. via e-mail) with an accompanying SpaServer that functions as operative source for all new spa-repeat and -types codes.

Thus, the Ridom SpaServer can be used to collate and harmonize data from various geographic regions. In order to simplify spa-type nomenclature, a numerical repeat code was established. This approach was chosen despite of the currently existing different alpha-numerical nomenclatures, because numerical codes are now widely used for multi locus sequence typing (MLST). An online conversion of the old terminology into the new one is possible.

The WWW site (spaserver.ridom.de) is freely accessible to internet users and the spa-repeat sequences and the -types can be downloaded. Chromatograms of new spa-repeats and/or -types can be submitted online for inclusion into the reference database. Therefore, it is possible also for users not working with Ridom software to use the same uniform terminology (open system).

DNA Sequencing of the spa Gene

Harmsen D, Claus H, Witte W, Rothgänger J, Claus H, Turnwald D, Vogel U (2003). Typing of methicillin-resistant Staphylococcus aureus in a university hospital setting using a novel software for spa-repeat determination and database management. J. Clin. Microbiol. 41 [PubMed].

Mellmann A, Friedrich AW, Rosenkötter N, Rothgänger J, Karch H, Reintjes R, Harmsen D. (2006). Automated DNA sequence-based early warning system for the detection of methicillin-resistant Staphylococcus aureus outbreaks. PLoS Med. 3(3). [PubMed].