Neutrophil to lymphocyte ratio (NLR) and YKL-40 as potential markers for discriminating mycoplasma pneumoniae pneumonia from viral pneumonia in children

Objectives: Our research aimed to explore the potential indicators in discriminating mycoplasma pneumoniae pneumonia (MPP) from viral pneumonia (VP) in children. Methods: TaqMan PCR testing was used to detect respiratory pathogens in all pneumonia patients. The serum levels of IL-37 and YKL-40 were measured by ELISA. While the expression levels of YKL-40 and IL37 mRNA in PBMCs were detected by qRT-PCR. We calculated the neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) values from blood routine test results. This study had been registered in the Chinese Clinical Trials Registry System (MR-32-24-025608). Results: 170 patients were selected, including 85 MPP patients and 85 VP patients. In addition, 85 healthy control children were selected for comparison. The levels of serum YKL-40, IL-37 and their mRNA expressions in MPP patients were significantly higher than in VP patients and healthy control. Similarly, MPP patients had the highest levels of NLR and PLR. According to the ROC curve result, the combination of two indicators (YKL-40 and NLR) was the strongest predictor of MP vs. VP. Conclusions: These results indicate that YKL-40 and NLR constitute the critical combination of biomarkers useful for differentiating between MPP and VP in children.