The Clinical Significance of Pathogen Loads and Macrolide Resistance Levels for Macrolide-Resistant Mycoplasma pneumoniae Pneumonia in Children

Objective: Mycoplasma pneumoniae (M. pneumoniae) pneumonia presses a serious threat on children's health. This study was aimed to investigate the clinical significance of pathogen loads and macrolide resistance levels for macrolide-resistant M. pneumoniae (MRMP)-induced pneumonia in children.

Methods: Serum levels of inflammatory markers including lactic dehydrogenase (LDH), D-dimer, C-reactive protein (CRP) were tested. RT‒PCR was used for the detection of M. pneumoniae infection and the macrolide resistance levels. The patients were classified into high pathogen load and low pathogen load groups based on the Ct values of the p1 gene, and high macrolide resistance level and low macrolide resistance level groups based on the relative levels of macrolide resistance associated mutations to that of the p1 gene. The rates of alternative antibiotic use and hospitalization days were recorded, and the leukocyte counts were tested.

Results: The rates of elevated inflammatory markers from high to low were LDH, CRP and D-dimer. The Ct values of the p1 gene ranged from 19 to 35, and patients with higher pathogen loads had greater rates of alternative antibiotic use; higher levels of LDH, D-dimer, CRP and neutrophil counts (NEUT); and longer hospitalization durations. The range of the macrolide resistance levels was 0.31-2.11, and the rates of alternative antibiotic use, NEUT, CRP and D-dimer levels were higher in patients with higher macrolide resistance levels.

Conclusion: LDH was a more frequently elevated serum inflammatory marker than D-dimer and CRP, and the pathogen load and macrolide resistance levels possessed important clinical significance for MRMP-induced pneumonia in children.