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Background: How to early distinguish the severity of Mycoplasma pneumoniae pneumonia (MPP) is a worldwide concern in clinical practice. We therefore conducted this study to assess the relationship between levels of serum inflammatory chemokines and the severity of MPP., Methods: In this prospective study, we enrolled 39 children with MPP, whose clinical information was collected, blood samples were assayed for cytokines and chemokines by ELISA., Results: The levels of serum CXCL10 in children with severe MPP were significantly higher than those in children with mild MPP (2500.0 [1580.9-2500.0] vs. 675.7 [394.7-1134.9], P < 0.001). Measurement of CXCL10 levels in serum enabled the differentiation of children with severe MPP with an area under the curve (AUC) of 0.885 (95 % CI 0.779-0.991, P < 0.001), with a sensitivity of 81.0 % and a specificity of 83.3 %., Conclusions: Serum CXCL10 level may be a potential biomarker for severe MPP in children., (© 2021. The Author(s).)

Objective: Mycoplasma pneumoniae pneumonia (MPP) is an important disease in children. Studies have demonstrated that the levels of D-dimer are elevated in some children with MPP, especially those with thrombotic complications. However, the potential association between MPP and D-dimer remains unclear. In our study, we sought to explore the relationship between the levels of plasma D-dimer and clinical characteristics of MPP patients., Methods: Retrospective analysis was conducted on 356 patients who were hospitalized in our hospital for MPP between January 1, 2017, and December 31, 2019. According to the peak value of D-dimer, patients were divided into three groups: the normal group (D-dimer<0.55 mg/L), the mild-moderately elevated group (D-dimer 0.55-5.5 mg/L) and the severely elevated group (D-dimer >5.5 mg/L). The demographic and clinical information, radiological findings, laboratory data, and treatments of patients were compared among different groups., Results: 106 patients were in the normal group, 204 patients were in the mild-moderately elevated group, and 46 patients were in the severely elevated group. More severe clinical and radiographic manifestations, longer length of fever, hospital stay and antibiotic therapy duration, higher incidences of extra-pulmonary complications, refractory MPP (RMPP), severe MPP (SMPP) were found in the elevated group, when compared with the normal group ( P <0.01). Meanwhile, we found that the percentage of neutrophil (N%) and CD 8 + lymphocyte (CD 8 + %), C-reactive protein (CRP), lactate dehydrogenase (LDH), interleukin (IL)-6, IL-10, and interferon-gamma (IFN-γ) trended higher with increasing D-dimer, whereas the percentage of lymphocyte (L%) and prealbumin (PAB) trended lower ( P <0.01). In addition, the proportions of patients requiring oxygen therapy, glucocorticoid, bronchoscopy, immunoglobulin use, thoracentesis, or ICU admission were significantly higher in the severely elevated group than those in the other two groups ( P <0.01). Correlation analysis showed that N%, L%, CRP, LDH, IL-10, length of fever, length of stay, and length of antibiotic therapy had strong correlations with the level of D-dimer., Conclusions: MPP patients with higher levels of D-dimer had more severe clinical manifestations and needed longer duration of treatment, which might be closely related to the severity of lung inflammation after MP infection., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Zheng, Hua, Zhao, Li, Huang, Zhou, Wang, Chen and Zhang.)

To compare the different features of necrotizing pneumonia (NP) and non-NP (NNP) caused by Mycoplasma pneumoniae pneumonia (MPP) with large pulmonary lesions, and explore the predictor for NP to differentiate from MPP. A retrospective study of MPP patients with large pulmonary lesions hospitalized from January 2008 to December 2019 was enrolled, and clinical manifestations, laboratory findings, radiological findings were analyzed. Of 135 MPP patients with large pulmonary lesions, 56 were in the NP group, 79 were in the NNP group. We found the median length of fever days were much longer in NP group than those in NNP group. Higher levels of WBC, CRP, LDH, IL-6 in NP group were observed. Furthermore, the incidence of pulmonary consolidation was much higher in NP patients than that in NNP patients, while the CT value of large pulmonary lesion was much lower in NP patients. In ROC curve analysis, the cut-off values for the CT value and IFN-γ were 36.43 and 7.25 pg/ml, respectively. NP caused by MPP might be easier to suffer from prolonged clinical course, severe laboratory and radiological findings. CT value of large pulmonary lesions and IFN-γ could be used as biomarkers to predict NP from MPP with large pulmonary lesions in children.

Excessive immune responses played an important role in pathophysiology of mycoplasma pneumonia (MP) infection. Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) is a negative regulator of immune response. This study investigated the expression change of TIPE2 and its role in immune defense against MP infection, as well as the underlying mechanisms. Expressions of TIPE2 both in patients and in macrophages in vitro after MP infection were measured. We further studied cytokine production and mitogen-activated protein kinase (MAPK) signaling function in macrophages with interfered expression of TIPE2 upon MP infection. A significant decrease of TIPE2 mRNA expression was observed in peripheral blood mononuclear cells (PBMCs) from MP patients, which was correlated with the severity of infection. Accordingly we found down-regulation of TIPE2 expression in macrophages after MP infection. In vitro study further suggested that TIPE2 jeopardized inflammatory cytokine production trigged by MP infection via inhibiting MAPK signaling pathway. These findings provided evidences of the novel function of TIPE2 in anti-MP immunity and its possible clinical utility related clinical significance.

Excessive immune response against pathogens may play an important role in refracory Mycoplasma pneumoniae pneumonia (RMPP). The aim of this study was to elucidate the associations between cytokines and the prediction of RMPP in school-aged patients. Retrospective analysis was performed on school-aged children with Mycoplasma pneumoniae pneumonia (MPP) hospitalized in our hospital between January 1, 2011 and December 31, 2015. The clinical charcteristics, including the cytokines in serum between the RMPP group and the general Mycoplasma pneumoniae pneumonia (GMPP) group were compared and the predictive values of RMPP were explored. Of total 180 patients, 115 patients were in the GMPP group, 65 were in the RMPP group. We found the levels of cytokines, including nterleukin (IL)-6, IL-10, interferon gamma (IFN-γ) in RMPP group were significantly higher than those in GMPP group (P < 0.01). In ROC curve analysis, IL-10 and IFN-γ were useful for differentiating patients with RMPP from those with GMPP. Logistic regression analysis showed that the IL-10 ≥ 3.65 pg/ml and IFN-γ ≥ 29.05 pg/ml were significant predictors regarding to RMPP. Additionally, a positive correlation between serum IL-10 and IFN-γ concentrations was observed., Conclusions: IL-10 and IFN-γ could be used as the good predictors of RMPP in school-aged children.

Objective: To analyze the clinical characteristics of refracory Mycoplasma pneumoniae pneumonia (RMPP), and explore the related factors predicting RMPP., Methods: Retrospective analysis was performed on 634 children with Mycoplasma pneumoniae pneumonia (MPP) hospitalized in our hospital between January 1, 2011 and December 31, 2014. The clinical features, laboratory data, radiological findings between the RMPP group and the general Mycoplasma pneumoniae pneumonia (GMPP) group were compared and the predictive values of related factors were analyzed., Results: The median age of the RMPP patients (n = 145) was much older than that of the GMPP patients (n = 489) (P<0.01). We also found more severe presentations, higher incidence of extra-pulmonary complications and more serious radiological findings in RMPP group, which needed oxygen more often, longer antibiotics administration and intensive care (P<0.05). Meanwhile, the levels of C-reactive protein (CRP), lactic dehydrogenase (LDH), immunoglobulin A (IgM), interleukin (IL)-6, IL-10, interferon gamma (IFN-γ) and the percentage of neutrophils, CD8+ in RMPP group were significantly higher than those in GMPP group (P<0.05); while the levels of prealbumin (PAB) were lower than that in GMPP group (P<0.01). In ROC curve analysis, the percentage of neutrophil, CRP, LDH, PAB, IL-6, IL-10 and IFN-γ were useful for differentiating patients with RMPP from those with GMPP. Multiple logistic regression analysis showed that the CRP≥16.5mg/L, LDH ≥417IU/L and IL-6 ≥14.75pg/ml were significant predictors regarding to RMPP., Conclusions: CRP≥16.5mg/L, LDH ≥417IU/L and IL-6 ≥14.75pg/ml might be the significant predictors of RMPP in children, which can aid in early recognition of RMPP.

Introduction: This study prospectively evaluated the effect of early bronchoalveolar lavage (BAL) on refractory Mycoplasma pneumoniae pneumonia with radiologically proven large pulmonary lesions in children., Methods: A total of 35 children diagnosed as having refractory M. pneumoniae pneumonia with radiologically proven large pulmonary lesions completed the study. According to the time point of BAL, they were divided into 2 groups. In the early BAL group, BAL was performed within 3 d after admission (n = 22); in the late BAL group, BAL was performed 3 d later after admission (n = 13). Clinical effects were compared between these 2 groups., Results: After BAL therapy, improvement in clinical symptoms and laboratory findings as well as resolution of pulmonary lesions on radiography were obtained in all subjects. The median fever duration after admission was 4 (2-7) d and 5 (2-10) d (P < .05), and the median hospitalization duration was 7 (5-10) d and 10 (5-14) d (P < .05), respectively, in the early BAL group and the late BAL group. Approximately 7 d after admission, 67% of subjects in the early BAL group showed resolution of atelectasis on x-ray image versus a corresponding rate of 14% in the late BAL group (P < .05). Furthermore, laboratory indices recovered quicker in the early BAL group than in the late BAL group (P < .01)., Conclusions: BAL appeared to be efficacious and well-tolerated treatment for refractory M. pneumoniae pneumonia with radiologically proven large pulmonary lesions, and early application of BAL may be more beneficial., (Copyright © 2014 by Daedalus Enterprises.)

We sought to understand the situation of macrolide-resistant genotypes of Mycoplasma pneumoniae, and analyze the relationship between macrolide-resistant genotypes and clinical manifestations of Mycoplasma pneumoniae pneumonia (MPP). Full-length sequencing of the 23S rRNA gene of M. pneumoniae was performed in 235 nasopharyngeal aspirates (NPAs) from children with MPP. We also retrospectively compared the clinical characteristics of macrolide-resistant (MR) M. pneumoniae infections and macrolide-sensitive (MS) M. pneumoniae infections. A total of 206 patients had point mutations in the M. pneumoniae 23S rRNA gene, and these patients are referred to as MR patients. The remaining 29 patients without point mutations are referred to as MS patients. Among 206 MR patients, 199 (96.6%) had A2063G mutations, 6 had A2063T mutations, and the remaining patients had an A2064G mutation. Among the clinical manifestations, we found that the median fever durations were 8 days (range, 0 to 42 days) and 6 days (0 to 14 days) (P < 0.01), the median hospitalization durations were 8 days (2 to 45 days) and 6 days (3 to 16 days) (P < 0.01), and the median fever durations after macrolide therapy were 5 days (0 to 42 days) and 3 days (0 to 10 days) (P < 0.01), respectively, in the MR and MS groups. We also found that the incidence of extrapulmonary complications in the MR group was significantly higher than that in the MS group (P < 0.05). Moreover, the radiological findings were more serious in the MR group than in the MS group (P < 0.05). The increasing prevalence of MR M. pneumoniae has become a significant clinical issue in the pediatric patients, which may lead to more extrapulmonary complications and severe clinical features and radiological manifestations.