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Mycoplasma pneumoniae–Induced Rash and Mucositis Presenting With Persistent Mobitz Type I Atrioventricular Block in an 8-Year-Old

Year: 2026

Type: article

Abstract: BACKGROUND: Mycoplasma pneumoniae is a known causative agent for community-acquired pneumonia. Extrapulmonary manifestations can occur independently of pneumonia in Mpneumoniae infection, and cardiac involvement is around 1% to 5%. Myocarditis and pericarditis are often associated with mycoplasma infections. CASE SUMMARY: An 8-year-old girl presented with fever, conjunctivitis, rash, and swelling of the lips and extremities. Laboratory findings showed thrombocytopenia, hyponatremia, elevated inflammatory markers, elevated pro-B-type natriuretic peptide, elevated troponin I, and negative respiratory viral panel. Electrocardiogram indicated normal sinus rhythm, and echocardiography showed a small pericardial effusion, otherwise unremarkable. Intravenous immunoglobulin was initiated for presumed atypical Kawasaki disease. The patient's hospital course was notable for the development of asymptomatic Mobitz type I (Wenckebach) second-degree atrioventricular block on telemetry. Mycoplasma serology was performed, which was positive for Mpneumoniae IgM, leading to the diagnosis of Mpneumoniae-induced rash and mucositis (MIRM) with cardiac involvement. Doxycycline was initiated, which was followed by gradual normalization of inflammatory markers, troponin I, and resolution of pericardial effusion. Mobitz type I atrioventricular block subsequently resolved. DISCUSSION: Mpneumoniae is an atypical bacterium transmitted via respiratory droplets. Extrapulmonary manifestations are caused by direct invasion or by molecular mimicry-induced immune response. TAKE-HOME MESSAGES: MIRM mimics the symptoms of Kawasaki disease. Cardiac involvement in MIRM in the form of myopericarditis is common, whereas conduction abnormalities are rare in the pediatric age group. Early diagnosis of conduction abnormalities results in improved outcome.

Source: JACC Case Reports

DOI: 10.1016/j.jaccas.2025.106409

Authors: Mohanageetha Ardhanari, Hadiqa Memon, Gabriela Moraru

Institution: University of Oklahoma Health Sciences Center

Language: English

Topic: Microbial infections and disease research

Subfield: Microbiology

Field: Immunology and Microbiology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $850