Invasive group A streptococcal infections as a consequence of coexisting or previous viral infection in the post-COVID-19 pandemic period.

Background: Group A Streptococci (GAS) may cause infections of the pharynx and soft tissues and invasive infections in children (iGAS). A significant increase in severe iGAS infections has been reported in Europe since the fall of 2022.

Objectives: This retrospective study aims to analyse clinical data of children with invasive and non-invasive GAS infections in the post-COVID-19 pandemic era, searching for predisposing factors to developing invasive infections.

Methods: History and clinical data of patients hospitalised due to or with coexisting GAS infections were analysed. iGAS and non-iGAS infections were compared.

Results: The cohort comprised 45 children (median age 7 years). 31(69 %) children developed iGAS infections - sepsis with toxic shock syndrome (TSS) (4 children-13 %), deep soft tissue infections (3-10 %), meningitis (2-6 %), pneumonia (2-6 %) or respiratory tract infections - sinusitis or otitis (4-12 %). iGAS children developed complications more frequently (100 % vs 21 %, p < 0.0001) and required prolonged treatment (median 15 vs 10 days, p = 0.0001). Preceding or coexisting viral infections were more common in iGAS children (87 % vs 14 %; p < 0.0001). CRP and PCT were significantly higher in the iGAS group (median 17.95 vs 3.97 mg/dl, p = 0.0002; 6.8 vs 0.05 ng/ml, p = 0.0001, respectively). The multiple logistic regression revealed that preceding or coexisting viral infections and the rise in CRP level increased the risk of iGAS infections. The CRP cut-off > 14.94 mg/dl showed 68.2 % sensitivity (CI 45.13-86.14 %) and 100 % specificity (69.15-100 %).

Conclusion: Our study shows increased incidence and severity of GAS infections among hospitalised children. Previous or coexisting viral infections and CRP with cut-off > 14.94 mg/dl were significant risk factors.