New Insights on the Clinical Significance of Mycoplasma pneumoniae DNA Load in Mycoplasma pneumoniae Pneumonia

Objective This study aimed to assess the consistency of Mycoplasma pneumoniae (MP)-DNA load in the respiratory tracts, its correlation with Mycoplasma pneumoniae pneumonia (MPP) manifestations, and its predictive value for refractory Mycoplasma pneumoniae pneumonia (RMPP). Methods A retrospective study was performed on a cohort of MPP cases, including 215 patients with positive nasopharyngeal aspirate (NPA) MP-DNA and 59 with positive bronchoalveolar lavage fluid (BALF) MP-DNA. Patients were categorized into two groups based on MP-DNA load: low load (≤106/mL) and high load (>106/mL). The consistency of MP-DNA load in NPA and BALF was determined by Spearman's correlation coefficient. Clinical, laboratory, and radiological data were compared, and the predictive value of NPA MP-DNA for RMPP was evaluated using the receiver operating characteristic curve. Results A strong correlation was observed between NPA and BALF MP-DNA. High-load groups in both had longer fever durations and more pronounced increases in C-reactive protein, lactate dehydrogenase, and ferritin (p < 0.05). Routine-dose glucocorticoids were more required for patients exhibiting high MP-DNA loads, regardless of the source of the sample. The area under the curve for predicting RMPP using NPA MP-DNA load was 0.861, with 92.9% sensitivity and 67.9% specificity at a cutoff of 9.5 × 105/mL. Conclusion The NPA MP-DNA load reflects the severity of pulmonary inflammatory response. Increased MP-DNA load in both the upper and lower airways is associated with longer fever and increased inflammation, indicating a need for glucocorticoid therapy. NPA MP-DNA can predict RMPP with high sensitivity.