Evolving treatment strategies for invasive Streptococcus pyogenes in children in the postpandemic era.

Background: : Streptococcus pyogenes (group A Streptococcus [GAS]) is a common cause of bacterial pharyngitis and skin infections in children that can lead to severe and invasive GAS (iGAS) infections. The sudden acute respiratory syndrome coronavirus 2 pandemic coincided with an increase in iGAS cases, with emerging serotypes and risk factors like age, reduced postpandemic immunity, and viral coinfections. The treatment of iGAS with clindamycin and intravenous immunoglobulins (IVIG) is not well standardized, and pediatric data are limited. Linezolid is being explored as an alternative to clindamycin, although further research is required.

Purpose: : This study aimed to evaluate the treatment of iGAS in hospitalized children with focus on the effectiveness of standard treatments and the role of alternative interventions in cases of treatment failure, including the use of linezolid or severe infections. Additionally, this study sought to identify the potential risk factors for pediatric intensive care unit (PICU) admission.

Methods: : A retrospective observational study was conducted in children aged <18 years admitted to Meyer University Children's Hospital (September 2022 to September 2024) with confirmed or probable iGAS. Their anonymized general information, symptoms, laboratory test results, microbiological test results, coinfections, radiological examination results, antibiotic and nonantibiotic therapies, discharge information, and outcomes were collected.

Results: : Forty-six children with confirmed/probable iGAS (median age, 53.7 months) were included. Of them, 34 (73.9%) had confirmed iGAS and 12 (26.1%) had probable iGAS. Sixteen children (34.8%) with iGAS were admitted to the PICU; of them, 2 died. All children received beta-lactam antibiotics; in 5 cases (10.9%), linezolid was administered after beta-lactam and clindamycin therapy failure. Thirty patients (65.2%) underwent surgery. Of the study population, 22% had preexisting conditions and 17% had viral respiratory coinfections. Elevated C-reactive protein and procalcitonin levels were independent risk factors for PICU admission. IVIG administered to 3 patients had varying outcomes.

Conclusion: : Our findings highlight how treatment strategies and disease patterns have shifted in the postpandemic period. Pneumonia with a parapneumonic abscess or empyema has emerged as the most frequent clinical presentation, with nearly half of such cases requiring second-line linezolid therapy. Linezolid may be a valuable treatment alternative after beta-lactam and clindamycin failure. IVIG has been used in severe cases but often late, warranting further investigation into its optimal application.