Diagnostic Value of Serum Amyloid A and C-Reactive Protein in Children with Mycoplasma pneumoniae Infection

Background: This study was performed to determine the diagnostic value of serum amyloid A (SAA) and C -reac-tive protein (CRP) in children with Mycoplasma pneumoniae infection.Methods: In total, 862 patients with respiratory pathogenic infections who were admitted to Gansu Provincial Maternity and Child-care Hospital from September 2020 to August 2021 were selected and divided into different groups according to their pathogen types. One hundred healthy children were selected as the control group. SAA and CRP were detected by immune scattering turbidimetry. The results of CRP and SAA in each group were ex-pressed in quartiles. Differences between the control group and case group were assessed by the rank sum test, and comparisons between the two groups were conducted by the Mann-Whitney U test. The abundance of SAA and CRP was retrospectively analyzed and combined with the children's symptoms and imaging manifestations to determine the clinical significance of SAA and CRP in children with M. pneumoniae infection.Results: The SAA concentration was higher in patients with M. pneumoniae and virus coinfection than in patients with only M. pneumoniae infection, but there was no significant difference in CRP. The SAA and CRP concentra-tions were increased in patients with M. pneumoniae and other bacteria coinfection and in patients with M. pneu-moniae, other bacteria, and virus coinfection. Compared with M. pneumoniae infection alone, the area under the curve for diagnosis of M. pneumoniae coinfection with other pathogens by SAA, CRP, and their combination was 0.747, 0.708, and 0.741, respectively (p < 0.001), and the specificity and sensitivity of SAA were 81.74% and 61.23%, respectively.Conclusions: The levels of SAA and CRP are different among different M. pneumoniae infection groups. In pa-tients with M. pneumoniae coinfection, SAA has higher specificity and sensitivity than CRP. SAA can be used to predict the severity of M. pneumoniae infection.