Epidemiology and clinical features of Streptococcus pyogenes bloodstream infections in children in Madrid, Spain

Studies have shown increased invasive Group A Streptococcus (GAS) disease, including bloodstream infections (GAS-BSI). However, the epidemiological data of GAS-BSI are limited in children. We aimed to describe GAS-BSI in children in Madrid, over 13 years (2005-2017). Multicenter retrospective cohort study from 16 hospitals from Madrid, Spain. Epidemiology, symptomatology, laboratory, treatment, and outcome of GAS-BSI in children ≤ 16 years were analyzed. 109 cases of GAS-BSI were included, with incidence rate of 4.3 episodes/100,000 children attended at the emergency department/year. We compared incidence between two periods (P1: 2005-June 2011 vs P2: July 2011-2017) and observed a non-significant increase along the study period (annual percentage change: + 6.0% [95%CI: -2.7, + 15.4]; p = 0.163). Median age was 24.1 months (IQR: 14.0-53.7), peaking during the first four years of life (89/109 cases; 81.6%). Primary BSI (46.8%), skin and soft tissue (21.1%), and osteoarticular infections (18.3%) were the most common syndromes. We compared children with primary BSI with those with a known source and observed that the former had shorter hospital stay (7 vs. 13 days; p = 0.003) and received intravenous antibiotics less frequently (72.5% vs. 94.8%; p = 0.001) and for shorter duration of total antibiotic therapy (10 vs. 21 days; p = 0.001). 22% of cases required PICU admission. Factors associated with severity were respiratory distress, pneumonia, thrombocytopenia, and surgery, but in multivariate analysis, only respiratory distress remained significant (adjusted OR:9.23 [95%CI: 2.16-29.41]). Two children (1.8%) died.   Conclusion: We observed an increasing, although non-significant, trend of GAS-BSI incidence within the study. Younger children were more frequently involved, and primary BSI was the most common and less severe syndrome. PICU admission was frequent, being respiratory distress the main risk factor. What is known: • In recent decades, several reports have shown a worldwide increase in the incidence of invasive Group A streptococcal disease (GAS), including bloodstream infection (BSI). Recently, there have been a few reports showing an increase in severity as well. • There needs to be more information on the epidemiology in children since most studies predominantly include adults. What is new: • This study, carried out in children with GAS-BSI in Madrid, shows that GAS-BSI affects mostly younger children, with a broad spectrum of manifestations, needing PICU admission frequently. Respiratory distress was the leading risk factor for severity, whereas primary BSI seemed to be less severe. • We observed an increasing, although non-significant, trend of GAS-BSI incidence in recent years (2005-2017).