Children with MP infection exhibited comparable levels of mCD169 to those with viral infection (CD169 ratio: P = 0.384; CD169 index: P = 0.695), which were significantly higher than those in the healthy control (CD169 ratio: P < 0.001; CD169 index: P < 0.001) and bacterial infection groups (CD169 ratio: P < 0.001; CD169 index: P < 0.001). The gene discussed is SIGLEC1; the disease is bacterial infectious disease.