Severe Parapneumonic Effusion in a Child With Respiratory Syncytial Virus and Streptococcus pyogenes Coinfection

A four-year-old boy with respiratory syncytial virus (RSV) infection and suspected bacterial coinfection deteriorated despite antibiotic treatment. Intensive care and thoracoscopic debridement were required due to parapneumonic effusion. Despite negative pleural fluid cultures, next-generation sequencing detected group A streptococcus (GAS). Even in healthy children without risk factors, RSV infection preceding invasive GAS infection can rapidly deteriorate, making diagnosis difficult.