Etiological Diagnosis and Treatment Value of mNGS in Alveolar Lavage Fluid of Children with Severe Pneumonia.

OBJECTIVE: Metagenomic sequencing (mNGS) is a promising technique for pathogen detection. However, the use of mNGS in pediatric lung infections is still rarely reported.

METHODS: A total of 59 cases were included between January 2019 and December 2021. To compare the performance of mNGS and routine detection in diagnosing pulmonary infection and identifying pathogenic bacteria.

RESULTS: 59 children (33.90%) were infected with Mycoplasma pneumoniae, 15 were infected with adenovirus type 7 (25.42%), 11 were infected with Streptococcus pneumoniae (18.64%), 6 were infected with Staphylococcus aureus (10.17%), 5 were infected with Klebsiella pneumoniae, Acinetobacter baumannii, pertussis, and oral streptococcus (8.47%), 3 were infected with Haemophilus influenzae (5.08%), and 3 were infected with Pseudomonas aeruginosa (5.08%). Among 59 patients, 41 were co-infected with multiple pathogens and 18 were infected with independent pathogens. Mycoplasma pneumoniae infection was most common in 6 out of 18 independent pathogen patients (33%). Among them were 3 cases of type 7 adenovirus, 53 cases of human herpesvirus (16.7%), and 2 cases of pertussis bacillus (11.1%). One case (5.6%) was infected with Streptococcus pneumoniae, Proteus albicans, Mycobacterium tuberculosis, Staphylococcus aureus, and Klebsiella pneumoniae. In cases where routine testing results are negative, mNGS improves the diagnostic efficiency of mixed pulmonary infections. 17 cases (17/59=28.81%) were diagnosed as single infection through routine testing, and the mNGS results of 4 cases were consistent with routine testing, all of which were Mycoplasma pneumoniae infections. Three cases were tested for partial mNGS matching, of which one case tested positive for Mycoplasma pneumoniae antibody and tested positive for Mycoplasma pneumoniae infection and human infection γ Herpes virus type 4, one case tested positive for antibodies and tested for infection with Mycoplasma pneumoniae and Streptococcus pneumoniae. The routine examination results of the remaining 11 patients were inconsistent with the mNGS examination results. Two patients tested positive for Mycoplasma antibodies. Patient 17 presented with mNGS infection of Haemophilus, Neisseria, and adenovirus type 7, while another patient 18 presented with herpes virus type 5 infection.

CONCLUSION: mNGS is a promising technique for detecting co-pathogens in mixed pediatric lung infections, with potential benefits in terms of speed and sensitivity.