Association between microplastic exposure and macrolide resistance in mycoplasma pneumoniae pneumonia among younger children: A cross-sectional study in China.

Microplastics (MPs) are emerging environmental contaminants that pose potential health risks through inhalation, ingestion, and dermal contact. However, data on MP exposure and its impact on the pediatric respiratory system remain limited. This study aimed to assess MP levels in bronchoalveolar lavage fluid (BALF) and evaluate their associations with macrolide resistance in children with Mycoplasma pneumoniae pneumonia (MPP). BALF samples from 195 children aged 1-16 years were analyzed using Laser Direct Infrared (LDIR) spectroscopy and Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS). Six types of MPs were identified: Polyamide 66 (PA66) (92.31 %), Polyvinyl Chloride (PVC) (81.54 %), Polystyrene (PS) (78.97 %), Polyethylene (PE) (51.28 %), Polymethyl Methacrylate (PMMA) (21.02 %), and Polypropylene (PP) (11.28 %). MPs were detected in 194 out of 195 samples, with an overall detection rate of 99.48 %. Logistic regression showed that moderate exposure to PE (0.32-1.05 µg/mL) significantly increased the odds of macrolide-resistant MPP compared to low exposure (OR = 1.39; 95 % CI: 1.01-1.92; P < 0.05). Among children aged ≤ 6 years, high PE exposure was strongly associated with odds of macrolide-resistant MPP (OR = 2.62; 95 % CI: 1.37-5.02; P < 0.05), with a significant dose-response trend (P trend = 0.004). These findings provide the first evidence linking lower respiratory tract MP exposure with antibiotic resistance in pediatric MPP, particularly among younger children, and underscore the importance of minimizing environmental MP exposure in vulnerable populations.