Comparison in values of ratio of monocyte to neutrophil, particle agglutination method, and colloidal gold method in the diagnosis of children with mycoplasma pneumoniae infection

Objective To compare ratio of monocyte to neutrophil(MONO/NEUT), the particle agglutination method in detection of mycoplasma pneumoniae(MP)and colloidal gold method in detection of MP immunoglobulin M(MP-IgM)in the diagnosis of children with MP infection. Methods A total of 100 children with highly similar typical symptoms of MP infection were selected as research objects, and were detected by particle agglutination method for MP antibody, and by colloidal gold method for MP-IgM. The positive rates of particle agglutination method and colloidal gold method in children with different disease courses and ages were analyzed. Taking rapid cultivation microscopic examination as gold criteria, the sensitivity, specificity and accuracy of particle agglutination method and colloidal gold method were compared, and correlation between MONO/NEUT ratio and MP infection was analyzed. Results Out of 100 children, 68 cases were confirmed as positive MP. For those with the same course of disease and age, no significant difference was found in two methods(P>0.05). The positive rates of children with course of disease ≥7 d were significantly higher than those with course - of disease <7 d(P<0.05). There was no significant difference in positive rate between two methods in children with the same age(P>0.05). Compared with the children aged 60 days to 6 years, the positive rates of two methods in the children aged 7 to 14 years were higher(P<0.05). Among the 68 children with positive MP, the positive detection rate of particle agglutination method and colloidal gold method were 86.76%(59/68)and 89.71%(61/68)respectively, and there was no statistical difference between the two methods(P>0.05). There were no statistical differences in the sensitivity, specificity, accuracy between particle agglutination method and colloidal gold method(P>0.05). The increase rate of MONO/NEUT level in MP positive group was higher than that in MP negative group, and the difference was statistically significant(P<0.01). Kendall's tau-b grade correlation test results showed that the MONO/NEUT level was positively correlated with the positive MP results(r=0.565, P<0.001). Conclusion The colloidal gold method can obtain similar clinical results as the particle agglutination method for MP antibody detection in diagnosis of MP infection in children. Moreover, it is simple in operation, less time-consuming and requires lower professional quality of the detection personnel. Because MONO/NEUT level is positively correlated with the positive MP results, colloidal gold method combined with MONO/NEUT detection is recommended to obtain a better efficacy in diagnosis of MP in clinic.