Epidemiology of an upsurge of invasive group A streptococcal infections in Ireland, 2012–2015. Issue 3 (September 2018) - Meehan, Mary
Summary: Objectives: Group A streptococcus (GAS) is responsible for mild to very severe disease. The epidemiology of an upsurge in invasive GAS (iGAS) infections in Ireland, 2012–2015 was investigated. Methods: Epidemiological typing of iGAS ( n = 473) isolates was performed and compared to non-invasive ( n = 517) isolates. Clinical data of notified iGAS was obtained from the national infectious disease information system. Results: Annual incidences of iGAS cases ( n = 561) were 2.33–3.66 per 100, 000 population. Bacteraemia was the most common clinical presentation (75%) followed by focus without bacteraemia (19%) and necrotizing faciitis (7%). Streptococcal toxic shock syndrome occurred in 19% of presentations. The main invasive emm types in rank order were emm 1, emm 3, emm 28, emm 12 and emm 89 whereas emm 4, emm 28, emm 3, emm 12, emm 89 and emm 1 predominated in non-invasive infections. Invasive emm 1 and emm 3 showed annual fluctuations (15–48% and 4–37%, respectively) and predominated in most clinical presentations of iGAS. Superantigens speA, speG, speJ was associated with iGAS disease and, speC, speI and ssa with non-invasive infections. There was 4.3% erythromycin and 5.6% tetracycline resistance. The main resistant types were emm 11, emm 28 and emm 77. Conclusions: Cyclic increases in emm 1 and emm 3 occurred during the iGAS upsurge. Continued surveillance of GAS is therefore essential given the epidemiological changes that occur in a short time period.