Increasingly Frequent Parapneumonic Empyema by Group A Streptococcus Is More Severe Than by Streptococcus pneumoniae

Background: Streptococcus pneumoniae (Sp) is the leading bacterial pathogen causing complicated pneumonia, that is, with parapneumonic effusion/pleural empyema (PPE/PE). In 2022, there was a rise in group A Streptococcus (GAS)-complicated pneumonias in children. Methods: We reviewed the clinical characteristics of Sp- or GAS-complicated pneumonias admitted to 4 Portuguese tertiary hospitals, in 2018–2023. Results: Of the 128 cases, 107 were by Sp and 21 by GAS, with a rise in PPE/PE in 2023. Pathogens were identified by molecular methods (89.8%) or culture (16.4%) from pleural fluid or blood. The mean age was 3.8 years (standard deviation 2.9) and 52.3% were male. Children with GAS PPE/PE were more likely to have rash (57.1% vs. 3.8%, P < 0.001), pharyngitis (52.4% vs. 19.8%, P = 0.004), septic shock (28.6% vs. 0.9%, p <0.001), higher procalcitonin (PCT) (80 vs. 2.13 ng/mL, P = 0.005), higher rates of admission to the intensive care unit (81.0% vs. 55.1%, P = 0.030) and of invasive mechanical ventilation (38.1% vs. 11.2%, P = 0.005). Fatality rate was similar in both groups (4.8% vs. 0%, P = 0.164). Among cases where genotyping was possible, 4/7 GAS were emm 1 (3/4 M1 UK sublineage, all in 2023) and 64/88 Sp were serotype 3. Conclusions: Sp serotype 3 remains the leading cause of PPE/PE in children in Portugal. The increase in GAS PPE/PE cases in 2023 followed an expansion of the M1 UK sublineage in Portugal. GAS should be considered, especially in children presenting with rash, pharyngitis or higher PCT levels. Adequate antimicrobial and clinical management of GAS PPE/PE could be crucial to improve outcomes.