The Dynamical Evaluation Of Three Methods To Diagnose Mycoplasma Pneumoniae Infection In Children

Objective:To evaluate the diagnostic value of fluorescent quantitation PCR (FQ-PCR) for MP-DNA, enzyme-linked immunosorbent assay (ELISA) for MP-IgM antibodies and rapid culture for MP in children with mycoplasma pneumoniae infection dynamically.Methods:We used the three methods to detect the MP in 153 patients with MP infection (bronchitis and pneumonia) diagnosed by clinical manifestation and laboratory evidence, when the patients were hospitalized and discharged from the hospital. The positive results were rechecked at the time point of 1 month and 3 months of the disease course. The clinical findings including fever and cough were observed during the research period.Results:The initial detection rate of FQ-PCR, ELISA and MP rapid culture were 96.1%, 68.6% and 24.8% respectively. There were no significant difference of detection rate in varied age group and Macrolides uses group, while the detection rate of ELISA in course of> 7 days was significantly higher than that of course of≤7 days. At the one month of the disease course,63.2% of the MP-DNA was positive and 98.0% of the MP-IgM was positive.46patients (30.1%) had cough at the one month of the disease course, in which 30(65.2%) patients had both positive results of MP-DNA and MP-IgM. Among the 74 patients with positive MP-DNA,30 (40.5%) patients had cough. At the 3 months of the disease course,4 (8.7%)patients had cough, among which 2 patients (50%)had both positive results of MP-DNA and MP-IgM. There were positive results of MP-DNA and MP-IgM in 7 asymptomatic patients (6.5%) at the 3 months of the disease course.Conclusions:FQ-PCR detecting MP-DNA was the most sensitive method for diagnosing MP infection, followed by the ELISA detecting MP-IgM and MP rapid culture. At 1 month of the disease course, more than half of the patients had positive result of MP-DNA. There may be correlation between positive MP-DNA and cough. Most of MP-DNA disappeared more than 4 weeks. The positive rate of MP-IgM reach peak at discharge from hospital and remained a high level when follow-up to 3 months.