Mycoplasma pneumoniae（MP）is a cell wall-deficient pathogen positioned between viruses and bacteria，possessing a small genome undergoing continuous reduction and primarily transmitted via droplets. MP infection typically manifests as an acute process，inducing a series of immune responses in the host. However，some pediatric patients experience prolonged or recurrent infections following acute episodes，suggesting incomplete clearance of MP by the host and the pathogen evasion from immune surveillance through specific mechanisms，leading to chronic infection. In recent years，increasing research has revealed the immune evasion strategies enabling MP's long-term survival within the host. This review summarizes recent domestic and international advances in studying immune evasion mechanisms during chronic MP infection，aiming to provide reference for clinical diagnosis and treatment.

Objective:To investigate the prevalence of small intestinal bacterial overgrowth (SIBO) in patients with rosacea, and to analyze the relationship between breath test results and the occurrence of rosacea.Methods:Patients with rosacea were enrolled from the outpatient department of Xiangya Hospital from March 2022 to June 2023. The methane-hydrogen breath test was used to detect intestinal levels of methane and hydrogen in all patients to investigate the prevalence of SIBO. The basic information, clinical symptoms and severity, quality of life scores, gastrointestinal symptoms, and past medical history of the patients were collected. Statistical analysis was carried out by using the chi-square test, nonparametric test and multivariate logistic regression models to investigate the relationship between SIBO and the occurrence of rosacea.Results:A total of 116 patients with rosacea completed the methane-hydrogen breath test. They were aged 18 to 56 years (median [ Q1, Q3]: 25 [22, 33] years), and included 7 males (6.0%) and 109 females (94.0%) ; there were 43 cases (37.1%) of erythematotelangiectatic rosacea, and 73 (62.9%) of papulopustular rosacea. As the breath test showed, 94 patients were diagnosed with SIBO (81.0%, 95% CI: 72.7% - 87.7%) based on the breath tests, 84 showed positive hydrogen breath test results (72.4%, 95% CI: 63.3% - 80.3%), and 47 had positive methane breath test results (40.5%, 95% CI: 31.5% - 50%). Among the 67 patients with moderate to severe erythema, 33 (49.3%) showed positive methane breath test results, and 14 of 49 (28.6%) patients with mild erythema showed positive methane breath test results, with a rate difference of 20.7% ( P = 0.025, 95% CI: 13.9% - 27.5%) ; there were no significant differences in the positive rates of SIBO and hydrogen breath test results between the patients with moderate to severe erythema and those with mild erythema (both P > 0.05). No significant differences were observed in the age, gender, clinical subtypes, severity of papulopustules, flushing and burning sensation, or rosacea quality of life index scores between the SIBO-positive and -negative groups, between hydrogen-positive and -negative groups, and between methane-positive and -negative groups (all P > 0.05). Multivariate logistic regression analysis showed that methane positivity on breath test was associated with the severity of erythema in rosacea ( OR = 2.495, 95% CI: 1.102 - 5.649, P < 0.05) . Conclusions:The prevalence of SIBO was relatively high in the patients with rosacea. However, only the positive rate of methane breath test differed between the rosacea patients and non-rosacea controls, and there was some correlation between methane positivity on breath test and increased severity of rosacea erythema.

Objective:To explore the value of circ_0054633 in early diagnosis and prognosis prediction of acute lung injury/acute respiratory distress syndrome (ALI/ARDS) in children with severe pneumonia.Methods:A retrospective case-control study was conducted on children with diagnosed severe pneumonia admitted to Tianjin Children's Hospital from July 1, 2022, to February 29, 2024. The clinical data was collected by electronic medical record system and clinical follow-up, including gender, age, lung injury prediction score (LIPS), pediatric critical illness score (PCIS), serum circ_0054633, interleukin-6 (IL-6), the indicators of the arterial blood-gas analysis, oxygenation index (PaO 2/FiO 2) within 24 hours of admission and the survival status of 28 days. According to whether ALI/ARDS occurred, they were divided into the ALI/ARDS group and the non-ALI/ARDS group. The differences of clinical data between the two groups were compared, and multivariate Logistic regression was used to analyze the risk factors for ALI/ARDS in children with severe pneumonia. The receiver operator characteristic curve (ROC curve) will be used to explore the early diagnostic value of ALI/ARDS in children with severe pneumonia. The patients of ALI/ARDS were divided into mild group, moderate group and severe group according to the level of PaO 2/FiO 2. The levels of serum circ_0054633 and IL-6 in various severity ALI/ARDS were compared. The differences of serum circ_0054633, IL-6 levels, PCIS score and LIPS score were compared between the two groups of ALI/ARDS patients according to different prognoses in 28 days, as well as the correlation between various risk factors and circ_0054633. Results:A total 74 children with severe pneumonia were included, with 34 cases in the ALI/ARDS group and 40 cases in the non-ALI/ARDS group. In ALI/ARDS group, there were 9 cases in the mild group, 15 cases in the moderate group and 10 cases in the severe group; while 12 cases died and 22 cases survived after 28 days. The serum circ_0054633, IL-6 level and LIPS score were higher in the ALI/ARDS group than the non-ALI/ARDS group, while the PCIS score was lower, and the two groups had significant difference. Multivariate Logistic regression analysis showed that circ_0054633 was independent predictors of ALI/ARDS in children with severe pneumonia [odds ratio ( OR) = 3.853, 95% confidence interval (95% CI) was 1.912-7.805, P = 0.017]. ROC curve analysis showed that the cut-off values for circ_0054633 in the diagnosis of ALI/ARDS were 3.955, sensitivity was 79.4%, specificity was 92.5%, area under the ROC curve (AUC) was 0.892. The serum circ_0054633 and IL-6 levels were higher in the children who died in 28 days than the children who were survived, while the PCIS score was lower, and the two groups had significant difference. Spearman correlation analysis showed that the level of circ_0054633 in children with ALI/ARDS was positively correlated with 28-day mortality and IL-6 ( r value was 0.675, 0.763, respectively, all P < 0.001), but negatively correlated with PCIS score ( r = -0.626, P < 0.001), while no significant correlation with LIPS score ( r = 0.389, P = 0.023). Conclusion:The level of serum circ_0054633 has a better value in early diagnosis and prognosis prediction of ALI/ARDS caused in children with severe pneumonia.

Objective:To analyze the status of respiratory pathogen detection and the clinical features in children with Mycoplasma pneumoniae pneumonia (MPP). Methods:A prospective, multicenter study was conducted to collect clinical data, including medical history, laboratory examinations and multiplex PCR tests of children diagnosed with MPP from 4 hospitals in China between November 15 th and December 20 th, 2023. The multiplex PCR results and clinical characteristics of MPP children in different regions were analyzed. The children were divided into severe and mild groups according to the severity of the disease. Patients in the severe group were further divided into Mycoplasma pneumoniae (MP) alone and Multi-pathogen co-detection groups based on whether other pathogens were detected besides MP, to analyze the influence of respiratory pathogen co-detection rate on the severity of the disease. Mann-Whitney rank sum test and Chi-square test were used to compare data between independent groups. Results:A total of 298 children, 136 males and 162 females, were enrolled in this study, including 204 children in the severe group with an onset age of 7.0 (6.0, 8.0) years, and 94 children in the mild group with an onset age of 6.5 (4.0, 7.8) years. The level of C-reactive protein, D-dimer, lactic dehydrogenase (LDH) were significantly higher (10.0 (5.0, 18.0) vs. 5.0 (5.0, 7.5) mg/L, 0.6 (0.4, 1.1) vs. 0.5 (0.3, 0.6) mg/L, 337 (286, 431) vs. 314 (271, 393) U/L, Z=2.02, 2.50, 3.05, all P<0.05), and the length of hospitalization was significantly longer in the severe group compared with those in mild group (6.0 (6.0, 7.0) vs. 5.0 (4.0, 6.0) d, Z=4.37, P<0.05). The time from onset to admission in severe MPP children was significantly shorter than that in mild MPP children (6.0 (5.0, 9.5) vs. 9.0 (7.0, 13.0) d, Z=2.23, P=0.026). All patients completed the multiplex PCR test, with 142 cases (47.7%) MPP children detected with 21 pathogens including adenovirus 25 cases (8.4%), human coronavirus 23 cases (7.7%), rhinovirus 21 cases (7.0%), Streptococcus pneumoniae 21 cases (7.0%), influenza A virus 18 cases (6.0%). The pathogens with the highest detection rates in Tianjin, Shanghai, Wenzhou and Chengdu were Staphylococcus aureus at 10.7% (8/75), adenovirus at 13.0% (10/77), adenovirus at 15.3% (9/59), and both rhinovirus and Haemophilus influenzae at 11.5% (10/87) each. The multi-pathogen co-detection rate in severe MPP children was significantly higher than that in mild MPP group (52.9% (108/204) vs. 36.2% (34/94), χ2=10.62, P=0.005). Among severe MPP children, there are 89 cases in the multi-pathogen co-detection group and 73 cases in the simple MPP group. The levels of LDH, D-dimer and neutrophil counts in the multi-pathogen co-detection group were significantly higher than those in the simple MPP group (348 (284, 422) vs. 307 (270, 358) U/L, 0.8 (0.5, 1.5) vs. 0.6 (0.4, 1.0) mg/L, 4.99 (3.66, 6.89)×10 9vs. 4.06 (2.91, 5.65)×10 9/L, Z=5.17, 4.99, 6.11, all P<0.05). Conclusions:The co-detection rate of respiratory pathogens, LDH and D-dimer in children with severe MPP were higher than those with mild MPP. Among severe MPP children the stress response of children in co-detection group was more serious than that of children with simple MPP.

Objective:To explore the clinical characteristics and predictive factors for plastic bronchitis (PB) in children with severe Mycoplasma pneumoniae pneumonia (SMPP). Methods:A retrospective cohort enrolled children with a clinical diagnosis of SMPP who were treated at the Department of Respiratory Medicine of Tianjin Children′s Hospital Machang District from January 1, 2018, to October 31, 2023. According to the bronchoscopy and pathological examination results, the patients were divided into 142 cases in the PB group and 274 cases in the non-PB group. The clinical manifestations, laboratory data, imaging findings, and treatments were analyzed.Mann-Whitney U test and Chi-square test were used to analyze the differences between the two groups, and multivariate Logistic regression was used to analyze the risk factors. The receiver operating characteristic (ROC) curve was used to explore the predictive value of PB in SMPP. Results:Among 416 SMPP children, there were 197 males and 219 females; PB group 142 cases, non-PB group 274 cases, the age of disease onset was (6.9±2.9) years and (6.6±2.8) years in the PB group and the non-PB group respectively. The incidence of wheezing symptoms, hypoxemia, heat peak >40 ℃, the duration of fever, neutrophil-lymphocyte ratio, mean platelet volume, C-reactive protein, procalcitonin, interleukin-6, alanine transaminase, aspartate aminotransferase and ferritin were higher in the PB group (16 cases (11.3%) vs. 15 cases (5.5%), 14 cases (9.9%) vs. 12 cases (4.4%), 57 cases (40.1%) vs. 67 cases (24.5%), 10 (8, 12) vs. 9 (8, 12) d, 6.1 (4.1, 13.1)×10 9vs. 5.0 (3.7, 6.8)×10 9/L, 10.2 (9.6, 10.8) vs. 9.4 (8.9, 10.1) fl, 33.4 (16.0, 67.5) vs. 23.0 (10.4, 56.1) mg/L, 0.24 (0.12, 0.48) vs. 0.16 (0.09, 0.31) μg/L, 39.9 (25.1, 81.4) vs. 31.3 (18.3, 59.3) ng/L, 16.0 (12.0, 29.0) vs. 14.0 (10.0, 24.3) U/L, 38.5 (28.0, 52.5) vs. 33.0 (25.0, 44.0) U/L, 233 (136, 488) vs. 156 (110, 293) μg/L, χ2=4.55, 4.79, 11.00, Z=2.25, 4.00, 6.64, 2.76, 2.98, 3.09, 2.22, 2.62, 4.18, all P<0.05). Multivariate Logistic regression analysis showed that the dyspnea ( OR=2.97, 95% CI 1.35-6.55, P=0.007), the diminution of respiration ( OR=2.40, 95% CI 1.27-4.52, P=0.006), neutrophil-lymphocyte ratio (NLR) ( OR=2.07, 95% CI 1.71-2.51, P<0.001), lactate dehydrogenase (LDH) ( OR=1.01, 95% CI 1.00-1.01, P<0.001), mean platelet volume/platelet count (MPV/PLT) ( OR=1.39, 95% CI 1.13-1.71, P=0.002), pleural effusion ( OR=2.23, 95% CI 1.21-4.13, P=0.011),≥2/3 lobe consolidation ( OR=1.84, 95% CI 1.04-3.00, P=0.039) and atelectasis ( OR=1.98, 95% CI 1.02-3.48, P=0.044) were independent predictors of PB in children with SMPP. ROC curve analysis showed that the cut-off values for NLR, LDH and MPV/PLT in the diagnosis of PB were 2.79 (sensitivity 0.89, specificity 0.69, area under the curve (AUC)=0.86, P<0.001), 474 U/L (sensitivity 0.63, specificity 0.65, AUC=0.70, P=0.003) and 0.04 (sensitivity 0.75, specificity 0.53, AUC=0.68, P=0.005) respectively. Children in the PB group had longer hospital stays and corticosteroid treatment course than those in the non-PB group, the proportion of children in the PB group who received bronchoscopy treatment twice or more was higher (9 (8, 12) vs. 8 (6, 10) d, 7 (5, 8) vs. 6 (5, 7) d, 128 cases (90.1%) vs. 218 cases (79.6%), 106 cases (74.7%) vs. 54 cases (19.7%), Z=6.70, 5.06, χ2=7.48, 119.27, all P<0.05). Conclusions:The dyspnea, respiration diminution, NLR level elevation (>2.79) and pleural effusion were predictive factors for PB in children with SMPP. This provides a basis for the early identification of PB in children with SMPP.

As a biomarker of airway inflammation, alveolar exhaled nitric oxide(CaNO), which represents small airway inflammation, is increasingly used in respiratory diseases.CaNO not only can be applied to children bronchial asthma severity evaluation, the selection of treatment and treatment effect of the dynamic monitoring, can also be applied to the early diagnosis of interstitial lung disease and assessment of the severity of lung damage for other diseases such as tuberculosis, pulmonary hypertension diagnosis.This paper reviews the diagnostic and therapeutic value of CaNO in pediatric respiratory diseases, and discusses the role of CaNO in the diagnosis and therapeutic evaluation in pediatric lung diseases.

Human adenovirus pneumonia(adenovirus pneumonia for short)is one of the important types of community-acquired pneumonia in children.Severe pneumonia can easily occur in infants or patients with impaired immune function, which can lead to acute lung injury and pulmonary sequelae.In severe infection, the significant imbalance between inflammatory cells and cytokines leads to tissue damage.In this paper, the classification, structure, infection receptor of human adenovirus and the immunological pathogenesis of adenovirus pneumonia are described.

Clara cell secretory protein 16(CC16)is one of the most important secreted proteins of Clara cells in respiratory epithelium, which mainly exists in the lining fluid of lung epithelial cells.When the bronchoalveolus-capillary membrane barrier is damaged, a large amount of CC16 will enter the blood.It′s eventually excreted in the urine.In recent years, more and more studies have found that CC16 not only has anti-inflammatory, immune-modulating, anti-oxidation and anti-fibrosis effects, but also is a sensitive indicator of the integrity of the airway epithelium, which can predict the occurrence and development of many children′s pulmonary diseases.This article mainly summarizes the biological characteristics and functions of CC16, and summarizes the research progress of CC16 in the diagnosis and treatment of pediatric pulmonary diseases.

Objective:To investigate the clinical characteristics and vaccination status of SARS-CoV-2 Omicron variant infected children.Methods:A total of 105 children infected with Omicron variant admitted to Tianjin Haihe Hospital (designated referral hospital for SARS-CoV-2 infection in Tianjin) from January 8, 2022 to February 3 were included for a retrospective study. The cases were divided into pneumonia group and non-pneumonia group according to chest imaging. Based on the doses of inactivated SARS-CoV-2 vaccine, the children who completed SARS-CoV-2 antibody test within 3 days after hospitalization were divided into 2 dose group and<2 dose group.Rank sum test and Chi-square test were used for the comparison between the groups.Results:The age of these 105 children was 10 (8, 11) years on admission, 53 children were males and 52 were females. Eighty-seven cases (82.9%) had mild symptoms, 13 cases (12.4%) had common symptoms and 5 cases (4.8%) were asymptomatic. Ninety-one cases (86.7%) completed 2 doses vaccination. The clinical symptoms were characterized by cough (74 cases, 70.5%), fever (58 cases, 55.2%), sore or dry throat (34 cases, 32.4%), nasal congestion (28 cases, 26.7%), rhinorrhea (23 cases, 21.9%). None of the children received antivirals, steroids, immunosuppressant or oxygen therapy. Seventy-six cases(72.4%) received traditional Chinese medicine treatment. The pneumonia group had a higher rate of positive SARS-CoV-2 IgG within 1 day after admission (13/13 vs. 87.0% (80/92), χ 2=42.81, P<0.001) than the non-pneumonia group. Among the 62 children who had serial SARS-CoV-2 antibody tests within 3 days after hospitalization, Compared to the<2 dose group, the 2 dose group had a higher rate of nucleic acid conversion within 16 days after onset and a higher rate of positive SARS-CoV-2 IgG 1 day after admission and 3 days after hospitalization (96.4% (54/56) vs. 4/6, 100.0% (56/56) vs. 2/6, 100.0% (56/56) vs. 3/6, all P<0.05). Conclusions:Most children infected with Omicron variant have mild symptoms, mainly respiratory infection symptoms. The proportion of SARS-CoV-2 antibody IgG positive in children who have received 2 doses of inactivated SARS-CoV-2 vaccines is higher,and the time of whose nucleic acid conversion may be shortened.

Objective:To investigate the clinical characteristics and vaccination status of SARS-CoV-2 Omicron variant infected children.Methods:A total of 105 children infected with Omicron variant admitted to Tianjin Haihe Hospital (designated referral hospital for SARS-CoV-2 infection in Tianjin) from January 8, 2022 to February 3 were included for a retrospective study. The cases were divided into pneumonia group and non-pneumonia group according to chest imaging. Based on the doses of inactivated SARS-CoV-2 vaccine, the children who completed SARS-CoV-2 antibody test within 3 days after hospitalization were divided into 2-dose group and <2-dose group.Rank sum test and Chi-square test were used for the comparison between the groups.Results:The age of these 105 children was 10.0 (8.0, 11.0) years on admission, 53 children were males and 52 were females. Eighty-seven cases (82.9%) had mild symptoms, 13 cases (12.4%) had common symptoms and 5 cases (4.8%) were asymptomatic. Ninety-one cases (86.7%) completed 2 doses vaccination. The clinical symptoms were characterized by cough (74 cases, 70.5%), fever (58 cases, 55.2%), sore or dry throat (34 cases, 32.4%), nasal congestion (28 cases, 26.7%), rhinorrhea (23 cases, 21.9%). None of the children received antivirals, steroids, immunosuppressant or oxygen therapy. Seventy-six cases (72.4%) received traditional Chinese medicine treatment. The pneumonia group had a higher rate of positive SARS-CoV-2 IgG within 1 day after admission (13/13 vs. 87.0% (80/92), χ 2=42.81, P<0.001) than the non-pneumonia group. Among the 62 children who had serial SARS-CoV-2 antibody tests within 3 days after hospitalization, Compared to the <2-dose group, the 2-dose group had a higher rate of nucleic acid conversion within 16 days after onset and a higher rate of positive SARS-CoV-2 IgG 1 day after admission and 3 days after hospitalization (96.4% (54/56) vs. 4/6, 100.0% (56/56) vs. 2/6, 100.0% (56/56) vs. 3/6, all P<0.05). Conclusions:Most children infected with Omicron variant have mild symptoms, mainly respiratory infection symptoms. The proportion of SARS-CoV-2 antibody IgG positive in children who have received 2 doses of inactivated SARS-CoV-2 vaccines is higher,and the time of whose nucleic acid conversion may be shortened.