Rapid Clinical Response to Ivig in Mis-C Associated With Co-Infection of Adenovirus and Chlamydia Pneumoniae: A Pediatric Case Report

Introduction. Multisystem Inflammatory Syndrome in Children (MIS-C) is a severe inflammatory condition predominantly associated with SARS-CoV-2 infection. While COVID-19 is the primary trigger, this case report presents MIS-C provoked by a mixed infection of ade­novirus and Chlamydia pneumoniae, highlighting the impact of co-infections. Case description. A 9-year-old boy presented with high fever, abdominal pain, generalized rashes, and lethargy. Despite initial suspicion of tonsilitis, his condition wor­sened, progressing to respiratory distress and systemic inflammation. Laboratory tests revealed elevated CRP, procalcitonin, ferritin, alongside lymphopenia and hy­ponatremia. Imaging revealed pleural effusion and mild cardiac dysfunction. A respiratory virus panel detected adenovirus, Chlamydia pneumoniae IgM titer was low-positive, and SARS-CoV-2 IgG antibodies were elevated. A coagulation test showed elevated D-dimer levels and prolonged prothrombin time, consistent with MIS-C-as­sociated hypercoagulability. MIS-C was diagnosed after extensive testing excluded other bacterial infections and Kawasaki disease. The patient received IVIG (2 g/kg), broad-spectrum antibiotics, and supportive care, with rapid clinical improvement and full recovery. Conclusion. This case illustrates the importance of early MIS-C recognition and considering alternative or additio­nal infectious triggers. A multidisciplinary management is essential for timely diagnosis and successful treatment.