Poor accuracy of single serological IgM tests in children with suspected acute Mycoplasma pneumoniae infection in Guangzhou, China.

Introduction. Early and accurate diagnosis of Mycoplasma pneumoniae (MP) infection of children with pneumonia is at the core of treatment in clinical practice.Gap Statement. Serological immunoglobulin M (IgM) tests for MP infection of children in south China have been rarely described.Aim. To assess the diagnostic performance and clinical application of serodiagnosis of MP infection in paediatric pneumonia patients.Methodology. Serum samples from 144 children diagnosed with MP pneumonia were subjected to a particle agglutination (PA)-based IgM assay. Meanwhile, we used an established suspension array as the reference standard method for the detection of MP DNA in bronchoalveolar lavage fluid (BALF) from all patients to assess the reliability of serological assays.Results. When running immunological testing in single serum samples, 80.6 %(79/98) of cases were diagnosed with MP infection, whereas only 55 (56.1 %) cases were positive in MP DNA analysis. Furthermore, single serum tests for IgM during acute MP infection resulted in 85.5 % (47/55) sensitivity and 25.6 % (11/43) specificity. Nevertheless, immunological testing and MP DNA analysis yielded the same results when paired sera were available for MP IgM antibody testing.Conclusion. Paired serological IgM assays are necessary for the determination of an acute MP infection, whereas single serological IgM testing is unreliable. Moreover, even a short interval of two MP serological tests works well.

[Relationship between the efficacy of inhaled corticosteroids and the leukotriene expression in children with asthma].

OBJECTIVE: To evaluate the relationship between leukotriene expression in blood polymorphonuclear leukocytes (PMNL) and the efficacy of inhaled corticosteroids (ICS) in children with asthma. METHODS: Thirty-two children with asthma (5-12 years) and ten healthy children (control group) were enrolled. The asthmatic children were subdivided into ICS well-controlled and ICS poorly-controlled groups based on their clinical symptoms and lung function. The level of leukotriene C4 synthase (LTC4S) mRNA in PMNL was detected by fluorescence quantitative polymerase chain reaction. The level of LTC4S mRNA was expressed by the value of qCt, and the value of qCt was diversely correlated with the level of LTC4S mRNA expression. The concentration of urinary leukotriene E4 (LTE4) was measured using ELISA. RESULTS: The expression of LTC4S mRNA in PMNL was significantly higher in children with asthma (qCt: 1.12+/-0.27) than that in the control group (qCt: 1.42+/-0.12; P< 0.05). The expression of LTC4S mRNA in PMNL in the ICS poorly-controlled group (qCt: 1.03+/-0.17) was significantly higher than that in the ICS well-controlled group (qCt: 1.24+/-0.33; P< 0.05) and the control group(1.42+/-0.12; P< 0.01). There was no significant difference in the level of urinary LTE4 among the the ICS poorly-controlled, the ICS well-controlled and the control groups. CONCLUSIONS: LTC4S mRNA expression in PMNL in asthmatic children increases, and the LTC4S mRNA expression in the ICS poorly-controlled group is higher than that in the ICS well-controlled group. This suggests that an increased leukotriene expression might be associated with poorly-controlled asthma.