Pathogenic Analysis in the Bronchoalveolar Lavage Fluid Samples with Pediatric Refractory <i>Mycoplasma pneumoniae</i> Pneumonia

Abstract

Background: We conducted a pathogenic analysis in the bronchoalveolar lavage fluid (BALF) samples from refractory Mycoplasma pneumoniae pneumonia (RMPP) children. Methods: The clinical process of 150 BALF samples from 60 RMPP patients were analyzed to investigate the process and tendency of pathogenic changes. The characteristics of M. pneumoniae were analyzed through culture, real-time PCR, genotyping, antimicrobial susceptibility testing and proteomics. The other pathogens were determined using culture, sequencing and nucleic acid detection kit. Results: In 60 RMPP cases, the bacterial co-infection rate was 5%, while that of virus was 33.3%. The poor prognosis rate was 61.7%. The 150 sample DNA positive rate was 98.7%, while the culture positive rate was 56.7% for M. pneumoniae. Significant differences were noticed in the positivity of M. pneumoniae culture obtained from samples with a disease course of at least 3 weeks compared with those within 3 weeks. The genotype 1 M. pneumoniae strains showed a macrolide resistant (MLr) rate of 100%, and that for genotype 2 was 90.1%. Proteomics showed that there were 57 proteins up-regulated in the MLs M. pneumoniae, half of them were membrane-associated protein with adhesion or toxicity. Pediatric RMPP usually presented viral co-infection, but it caused limited effects on the progression and prognosis of RMPP. Conclusion: Persistent presence of viable M. pneumoniae is not necessary in the later stage of RMPP. The expression of virulence factor in the MLr M. pneumoniae was higher than that of the MLs M. pneumoniae, which was more common in the RMPP children. Funding Statement: This study was funded by the Major Infectious Diseases Such as AIDS and Viral Hepatitis Prevention and Control Technology Major Projects (Grant No. 2018ZX10712-001), and the National Natural Science Foundation of China (Grant No. 81772154). Declaration of Interests: The authors stated: None. Ethics Approval Statement: Written informed consent was obtained from the patients. The study was approved by the Ethics Committee of National Institute for Communicable Disease Control and Prevention.