Application of colloidal gold method for detecting Mycoplasma pneumoniae-IgM combined with inflammatory factors in diagnosis of acute upper respiratory tract infection in children

Li Jianying; Lin Jianhua

doi:10.3969/j.issn.1674-7151.2024.04.004

Abstract：Objective To explore the application of colloidal gold method for detecting Mycoplasma pneumoniae(MP)-immunoglobulin M(IgM)combined with inflammatory factors in the diagnosis of acute upper respiratory tract infection in children.Methods Using retrospective research method,the 100 children with acute upper respiratory tract infection admitted to Dongguan Fenggang Hospital from January,2022 to December,2023 were selected for the study.According to whether MP-IgM detected by colloidal gold method was positive,the children were divided into MP positive group(50 cases)and MP negative group(50 cases).The clinical data[duration of fever,length of hospital stay,proportion of concurrent extrapulmonary symptoms,white blood cell count(WBC),neutrophil proportion(NEU%),lymphocyte proportion(LYM%),alanine aminotransferase(ALT)and alkaline phosphatase(ALP)]between two groups of children were compared.Enzyme linked immunosorbent assay(ELISA)was used to detect procalcitonin(PCT)and hypersensitive C-reactive protein(hs-CRP),and the differences in levels of above indicators between the two groups were compared.Using binary Logistic regression equation the correlation between PCT,hs-CRP and MP positivity was analyzed.The receiver operator characteristic curve(ROC curve)was drawn and the area under ROC curve(AUC)was calculated to analyze the predictive value of PCT and hs-CRP for acute upper respiratory tract MP infection.Results The levels of fever time,hospitalization time,proportion of concurrent extrapulmonary symptoms,WBC and NEU%in MP positive group were higher than those in MP negative group,and the level of LYM%was lower than that in MP negative group,with statistically significant differences[fever time(days):7.25±1.21 vs.5.82±1.07;hospitalization time(days):12.55±2.26 vs.8.13±1.76;proportion of concurrent extrapulmonary symptoms:46.00%vs.20.00%;WBC(×109/L):10.58±1.87 vs.8.94±1.62;NEU%:(74.39±6.78)%vs.(62.21±6.01)%;LYM%:(26.48±5.34)%vs.(40.81±6.15)%;all P<0.05].The serum levels of hs-CRP and PCT in MP positive group were higher than those in MP negative group[hs-CRP(mg/L):15.75±2.18 vs.13.15±2.06;PCT(ng/L):9.75±1.83 vs.6.99±1.64;both P<0.05].Serum hs-CRP and PCT were positively correlated with MP infection[odds ratios(OR)were 3.197 and 5.224,95%confidence intervals(95%CI)were 1.197-8.533 and 2.030-13.433,both P<0.05].The ROC curve analysis results showed that the AUC of hs-CRP and PCT were 0.856 and 0.867,95%CI were 0.782-0.931 and 0.797-0.937.Conclusion The levels of PCT and hs-CRP in children with MP positive and acute upper respiratory tract infection are elevated,indicating a certain correlation between these indicators and MP infection,which may serve as clinical observation indicators.