Invasive Group A Streptococcus infections in children during the post-pandemic period: results from a multicenter study in Italy

Background: Group A Streptococcus causes pediatric infections from mild to severe forms. Since late 2022, invasive cases have increased in Europe, possibly due to reduced post-COVID-19 immunity, more respiratory virus circulation, and emergence of virulent strains. Methods: A retrospective, multicenter observational study was conducted in twelve Italian pediatric Hospitals, including patients under 18 years hospitalized with invasive or severe Group A Streptococcus infection. Data were anonymized and analyzed to identify factors associated with Pediatric Intensive Care Unit (PICU) admission and discharge with sequelae or death. Results: Seventy-five children with invasive or severe Group A Streptococcus infection were included; the majority (69.3%) were aged 2–10 years. Invasive Group A Streptococcus (iGAS) infection accounted for 58.7% (n = 44) and severe GAS (sGAS) infection for 41.3% (n = 31) of cases. Pediatric Intensive Care Unit admission was required in 45.3% (n = 34) of the entire patient cohort, in this subgroup viral coinfection (OR 5.684, p = 0.003), sepsis/septic shock (OR 4.406, p = 0.003), iGAS diagnosis (OR 4.153, p = 0.005), and procalcitonin (PCT) > 0.5 ng/mL (OR 7.105, p = 0.019) were independently associated with admission; the use of corticosteroids (OR 4.641, p = 0.003) and intravenous immunoglobulin (IVIG) (OR 16.667, p = 0.003) was also significantly more frequent. All patients received empirical β-lactam antibiotics; anti-toxin therapy was administered in 47 patients (62.7%): clindamycin (49.3%), linezolid (16.0%), and rifampicin (1.3%). Mechanical ventilation was required in 24.0% (n = 18), and 49.3% (n = 37) underwent surgery. Post-infectious sequelae occurred in 20.0% (n = 15) and four children died, mostly due to streptococcal toxic shock syndrome. Conclusion: Pediatric invasive group A streptococcal infection continues to pose a significant clinical challenge, with notable rates of morbidity and mortality, underscoring the need for early recognition and close monitoring of high-risk patients. A widespread use of adjunctive therapies was documented. Continued surveillance and robust clinical research are essential to optimize management strategies and improve patient outcomes.