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HKU Finds Genetic Mutation in Streptococcus Pyogenes Possible Cause for the Recent Community Outbreak of Scarlet Fever

20 Jun 2011

The Department of Microbiology of the University of Hong Kong Li Ka Shing Faculty of Medicine and the Genome Research Centre at HKU have sequenced the genome of the Group A Streptococcus pyogenes strain that caused toxic scarlet fever of a child admitted to Queen Mary Hospital last week. The purpose of this sequencing project is to understand whether genetic mutation may be responsible for the recent large outbreak of scarlet fever and invasive streptococcal disease with one death at Queen Mary Hospital.

It is found that one unique genome fragment of 48 kilobase of about 2.5% of the genome was inserted inside the bacterial genome. This genome fragment is absent in the published genomes of two related strains of Streptococcus pyogenes. This genome fragment is likely to have come from other oral bacteria. The genetic recombination in Group A Streptococcus pyogenes may contribute to the increase of transmissibility of this strain. The findings provide important genetic information for tracking the spread of this new strain of Streptococcus pyogenes. The draft genome was finished within 3 days.

The project is partially funded by the Consultancy Service for Enhancing Laboratory Surveillance of Emerging Infectious Diseases for Department of Health and the Research Fund for the Control of Infectious Diseases (RFCID).