BackgroundRespiratory infectious complications remain a major cause of morbidity and mortality in children with hematological malignancies. Knowledge regarding the lung microbiome in aforementioned children is limited.MethodsA prospective cohort was conducted, enrolling 16 children with hematological malignancies complicated with moderate-to-severe lower respiratory tract infections (LRTIs) versus 21 LRTI children with age, gender, weight, and infection severity matched, with no underlying malignancies, to evaluate the lung microbiome from bronchoalveolar lavage fluid samples in different groups.ResultsThe lung microbiome from children with hematological malignancies and LRTIs showed obviously decreased α and β diversity; increased microbial function in infectious disease:bacteria/parasite; drug resistance:antimicrobial and human pathogenesis than the control group; a significantly reduced proportion of Firmicutes, Bacteroidota, Actinobacteriota; increased Proteobacteria at the phylum level; and distinctly elevated Parabacteroides, Klebsiella, Grimontia, Escherichia_Shigella, unclassified_Enterobacteriaceae at the genus level than the control group. Furthermore, it was revealed that α diversity (Shannon), β diversity (Bray–Curtis dissimilarity), Proteobacteria at the phylum level, and unclassified_Enterobacteriaceae and Escherichia_Shigella at the genus level were significantly negatively associated with hospitalization course whereas Firmicutes at the phylum level was established positively correlated with the hospitalization course.ConclusionsChildren with hematological malignancies and LRTIs showed obviously decreased α and β diversity, significantly increased function in infectious disease pathogenesis, antimicrobial drug resistance, and unfavorable environment tolerance. Moreover, α diversity (Shannon), β diversity (Bray–Curtis dissimilarity), and Proteobacteria may be used as negative correlated predictors for hospitalization course in these children whereas Firmicutes may be utilized as a positive correlated predictor.

BackgroundHost biomarkers and cytokines help in the prediction of disease severity in adults with community-acquired pneumonia (CAP). Accurate assessment of pathogens and disease severity is essential to clinical decision-making. There are few validated prognostic tools in blood and bronchoalveolar lavage for children with CAP to assist with proper decision and management.MethodsWe performed a retrospective study of 118 children under 18 years of age, hospitalized for CAP with bronchoalveolar lavage management within the first 2 days. The primary outcome was disease severity: mild (with no complications), moderate (with mild to moderate complications), and severe (with severe complications). Comparison and performance analysis of biomarkers and cytokines in the blood or bronchoalveolar lavage fluid (BALF) across different severity categories/different pathogens were performed.ResultsAnalysis of 118 CAP cases revealed significant differences in the BALF levels of IL-6 (p = 0.000), CRP (p = 0.001), and ESR (p = 0.004) across different severity categories, while BALF IL-6 level was indicated as the best indicator to discriminate mild from moderate-to-severe cases with highest AUC (0.847, 95% CI: 0.748–0.946), fair sensitivity (0.839), and specificity (0.450), and severe from non-severe cases with highest AUC (0.847), sensitivity (0.917), and specificity (0.725). ALL biomarkers and cytokines exhibited no significant differences across different pathogen categories (p > 0.05), while BALF IL-6 (p = 0.000), blood ANC (p = 0.028), and ESR (p = 0.024) levels were obviously different in comparison to single Mycoplasma pneumoniae (MP)-, bacteria-, or virus-positive group vs. non-group. Blood CRP (r = 0.683, p = 0.000) and ESR (r = 0.512, p = 0.000) levels revealed significant correlation with the hospitalization course (HC). Among all the BALF cytokines, only BALF IL-6 showed a significant difference (p = 0.004, p < 0.01) across different severity categories, with good performance for predicting CAP severity in hospitalized children (AUC = 0.875, P = 0.004). Blood IL-6 and BALF IL-6 levels showed no significant correlation; in addition, BALF IL6 was better at predicting CAP severity in hospitalized children (AUC = 0.851, p = 0.011, p < 0.05) compared to blood IL-6.ConclusionBALF IL-6 and blood CRP levels, and ESR may have the ability for discriminating disease severity in hospitalized children with CAP, whereas WBC count and ANC have limited ability. No biomarkers or cytokines seemed to have the ability to predict the pathogen category, while BALF IL-6, blood ANC, and ESR may assist in the diagnosis of single MP, bacteria, and virus infections, respectively.