Researchers at the Department of Laboratory Medicine, Children’s and Women’s Health (LBK), NTNU, has developed a better, quicker and cheaper method for typing group B streptococcus (GBS) based on repeated areas in the genome.
GBS can cause life-threatening infections in newborn, pregnant women or adults with chronic diseases. It also causes mastitis in cattle, lead researcher Assistant Professor Andreas Radtke explains.
The main motivation for the research is the abnormally high number of deaths among newborn due to GBS in Norway in 2006:
“Normally we have between zero and three deaths annually among otherwise healthy newborn in Norway. In 2006 we suddenly had six during the first half, and this increased to 10 by the end of the year. Some of these seemed to come from the same clone, but we did not reach sufficient conclusions with the available methods.”
In 2006 the laboratory used pulsed gelelectrophoresis and multi-locus sequence typing, but both are time consuming (up to one week) and do not give sufficient detail. The new MLVA method (see fact box) however, can produce a more detailed pictured within days.
The typing is done to see if stems of GBS are related to determine whether outbreaks are connected, or are isolated cases.
The microbiological department has conducted research into GBS for more than 30 years, and is the national reference laboratory for GBS.
A French group has developed a similar method, but with slightly different areas. Radtke says he will contact the French group to find a consensus method. He also plans a website for collecting and comparing results.
Radtke will defend his thesis “Molecular methods for typing of Streptococcus agalactiae with special emphasis on the development and validation of a multi-locus variable number of tandem repeats assay (MLVA)” on Wednesday 6 June 2012.
Multi-locus variable number of tandem repeat assay (MLVA) is based on the variability in repeated areas in the bacteria’s genome.
- Multiple-locus variant-repeat assay (MLVA) is a useful tool for molecular epidemiologic analysis of Streptococcus agalactiae strains causing bovine mastitis. Radtke etl.al. Vet Microbiol. 2012 Jun 15;157(3-4):398-404. Epub 2012 Jan 8.
- Rapid multiple-locus variant-repeat assay (MLVA) for genotyping of Streptococcus agalactiae. Radtke et.al. J Clin Microbiol. 2010 Jul;48(7):2502-8. Epub 2010 May 26.
- Identification of surface proteins of group B streptococci: serotyping versus genotyping. Radtke et.al. J Microbiol Methods. 2009 Sep;78(3):363-5. Epub 2009 Jun 30.
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