Host inflammatory markers and MLVA profiling for risk assessment of severe pediatric Mycoplasma pneumoniae pneumonia

Huan Xu, Jingmin Zhang, Shujuan Jiang, J H Xu, Xiaoqian Huang, Shuning Sun, Han Yan, Zhaoyong Lv, Daogang Qin, Yi-Xiang Wang, Ting Wang

Background Mycoplasma pneumoniae (MP) is a leading cause of community-acquired pneumonia in children (CAP). Rising macrolide resistance and variability in clinical severity have become growing concerns. This study aimed to describe the molecular epidemiology, resistance patterns, and risk factors for severe M. pneumoniae pneumonia (SMPP) in children from Liaocheng, Shandong Province, China. Methods We retrospectively enrolled 421 children hospitalized with MP pneumonia (MPP) between January 2023 and December 2024 in this study. Clinical and laboratory data were collected. M. pneumoniae -DNA-positive specimens were analyzed by 23S rRNA gene sequencing to identify macrolide resistance mutations, and by Multilocus Variable-Number Tandem Repeat Analysis (MLVA) for molecular typing. Univariate and multivariate logistic regression analyses were used to identify risk factors for SMPP. Results Of the 421 patients, 212 (50.4%) were diagnosed with SMPP. Children with SMPP were significantly older than those with general MPP (GMPP) ( P = 0.001). Elevated D-dimer and lactate dehydrogenase (LDH) levels were identified as independent risk factors for SMPP. Among 148 successfully sequenced specimens, 144 (97.30%) carried macrolide resistance mutations, with A2063G being the most common (96.62%). MLVA typing identified 14 distinct subtypes, the most prevalent were M2-4-5-7-2, M5-4-5-7-2, M3-4-5-7-2, and M4-3-5-6-2. The subtype M4-3-5-6–2 was associated with a lower risk of SMPP (OR = 0.155, 95% CI: 0.037-0.654), while the subtype M3-4-5-7–2 carried the highest risk (OR = 14.0, P = 0.001). Conclusion This study reveals a high rate of macrolide-resistant MP in Liaocheng, largely caused by the A2063G mutation. Elevated D-dimer and elevated LDH are independent predictors of SMPP. Certain MLVA subtypes are significantly associated with disease severity, suggesting they may help in risk assessment and clinical decision-making.