Associations of Mycoplasma pneumoniae load, co-infections, and macrolide resistance with clinical-laboratory profiles in hospitalized pediatric pneumonia: a targeted next-generation sequencing study of bronchoalveolar lavage fluid

PURPOSE: This study aimed to evaluate the associations of Mycoplasma pneumoniae (MP) DNA load, co-infection, and macrolide resistance with clinical phenotypes in pediatric pneumonia, using targeted next-generation sequencing (tNGS) of bronchoalveolar lavage fluid (BALF). METHODS: We conducted a retrospective cohort study of 791 hospitalized children with MP pneumonia. All patients underwent bronchoscopy, and BALF was analyzed using tNGS. This allowed for the simultaneous quantification of MP DNA load, comprehensive co-infection profiling, and detection of macrolide resistance mutations (A2063G/A2064G in 23 S rRNA). Clinical data were analyzed for associations with these multidimensional tNGS parameters using univariate and multivariable statistical methods. RESULTS: Our analysis indicated distinct clinical phenotypes associated with tNGS findings. A high MP DNA load was associated with a "classic" phenotype of persistent fever and lung consolidation, typically in monoinfection. Conversely, a low MP DNA load was a key biomarker for a co-infection-driven syndrome in younger children, characterized by more severe respiratory symptoms (wheezing, dyspnea) and systemic inflammation. Furthermore, macrolide-resistant MP (MRMP) was the factor most strongly associated with treatment failure, conferring a three-fold increase in the odds of requiring second-line antibiotics, without influencing initial disease severity. CONCLUSION: This study demonstrates that the integration of MP DNA load, co-infection status, and resistance profiling from BALF-based tNGS supports the use of a multidimensional framework for stratifying pediatric MP pneumonia. These data may help inform disease course anticipation and therapeutic strategy selection, contributing to the development of more personalized patient management.