Invasive group A streptococcal disease

National insight into the genomic epidemiology of iGAS

Invasive group A Streptococcal disease (iGAS) became nationally notifiable in Australia in July 2021, meaning that all iGAS isolates will likely be routinely shared with public health laboratories. The development of a national surveillance genomic framework will provide a centralised means of defining pathogenic GAS clusters. An iGAS national surveillance system will strengthen the ability and sensitivity of public health personnel to identify variant ‘clones’ of concern and the transmission of these clones between national nodes. The emergence of new pathogenic iGAS clones (such as "M1uk") has recently been identified in the Northern hemisphere, leading to a complete replacement of progenitor M1 populations and an increase in iGAS cases.

A recent study of iGAS in Victoria and QLD demonstrated the likely importation of M1uk into Australia with evidence of convergent prophage evolution resulting in an enhanced toxin profile. Monitoring the spread and replacement of such GAS clones into Australian health networks is currently lacking. Additionally, increasing macrolide resistance iGAS clones and isolates with altered penicillin sensitivity have been documented within surveillance nodes from high-income settings (eg US CDC). The genomic epi of iGAS has not been established at a national level, which is required for identifying problem clones and informing public health responses.

The project will contribute crucial genomic epidemiological data on the population dynamics, antimicrobial resistance and characteristics of strain types, aligned with the globally harmonised surveillance protocols for invasive Strep A disease recently updated and published by the Strep A Vaccine Global Consortium (SAVAC).

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Project Aims

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1.     To implement harmonised national analysis methodologies in AusTrakka

2.     Undertake national comprehensive snapshot over a 6-month period to unravel the genomic epidemiology of iGAS

3.     Develop a guidance document on iGAS genomic surveillance for public health laboratories and integrate with public health agencies

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