Abstract
Background evidence indicates that the macrolide-resistant EC2 mutant of Mycoplasma pneumoniae (MP) emerged as the predominant strain during the 2023-2024 epidemic, being associated with immune-mediated complications (e.g., severe immune thrombocytopenia [ITP]), whose clinical characteristics and prognosis remain undefined. This study aimed to compare the severity of bleeding, treatment response and long-term prognosis in children with newly diagnosed severe ITP and non-MP-associated ITP with MP-related mutations during the epidemic of EC2 mutant strains. A cohort of children with MP-ITP or non-MP ITP admitted to Beijing Children's Hospital from October 2023 to February 2024 was enrolled. Twelve-month outcomes included baseline platelet counts, bleeding severity, short-term responses (at 1 week/1 month/3 months), and sustained remission rates at 6/12 months. The MP group (n = 20, median age 6.4 years) showed lower baseline platelet counts (12.0 × 10⁹/L) and higher proportions of severe bleeding (grade 3/4: 30%) compared with non-MP controls (n = 46, median age 5.5 years; platelets 21.0 × 10⁹/L; grade 3/4: 13%). Following monotherapy/combination therapy, A one-way analysis of covariance(ANCOVA) revealed significantly higher platelet counts in MP-ITP at 3-12 months (p ≤ 0.008), with consistently higher complete response rates in MP-ITP (100% at 1 month, 90% at 12 months) than in non-MP controls (87% at 1 month, 78% at 12 months). In conclusion, MP-related ITP was characterized by severe bleeding but demonstrated favorable treatment responses and long-term outcomes, warranting further investigation of its immunopathogenic mechanisms.