Clinical Relationship Between Bronchoalveolar Lavage Fluid Mycoplasma Pneumoniae-dna Copies And Mycoplasma Pneumoniae Pneumonia

Objecticve:To explore relationship between bronchoalveolar lavage fluid Mycoplasma pneumoniae(MP)-DNA copies and Mycoplasma pneumoniae pneumonia(MPP)in children.Methods:A total of 433 children who underwent bronchoalveolar lavage were enrolled retrospectively and diagnosed with MPP and were hospitalized in Children’s Hospital of Chongqing Medical University from January 2016 to December 2019.The children were divided into low copy level group(MP-DNA copies≤10~6/ml)and high copy level group(MP-DNA copies>10~6/ml)according to the copy levels of MP-DNA in bronchoalveolar lavage fluid(BALF).The two groups were compared for their conditions in terms of basic data,clinical manifestations,laboratory results,chest imaging features,extrapulmonary complications,routine cytological examination and cytokines of bronchoalveolar lavage fluid,and the correlation between the copies of MP-DNA with the severity of MPP,refractory mycoplasma pneumoniae pneumonia(RMPP)and laboratory indexes of refractory mycoplasma pneumoniae pneumonia was discussed.Results:Compared with low MP-DNA copy group,high MP-DNA copy group had higher peak temperature,longer duration of total fever,longer duration of high fever,in peripheral blood the percentage of neutrophils,C-reactive protein(CRP),procalcitonin(PCT),lactate dehydrogenase(LDH),D-dimer,in BALF percentage of neutrophils,cytokines IL-6,IL-10,IFN-γand TNF-αwere increased((P<0.05).High MP-DNA copy group had a significantly higher incidences of massive consolidation or atelectasis,pleural effusion,extrapulmonary organ involvement and severe MPP and RMPP(P<0.05).The number of copies of MP-DNA was positively correlated with the percentage of neutrophils,CRP,PCT,LDH,D-dimer,BALF neutrophils,IL-6,IL-10,IFN-γand TNF-α.The correlation coefficients were r1=0.161,r2=0.197,r3=0.227,r4=0.156,r5=0.220,r6=0.155,r7=0.367,r8=0.511,r9=0.431,r10=0.354(P<0.05),respectively.There was a negative correlation between the number of MP-DNA copies and the percentage of peripheral blood lymphocytes(r=-0.154,P<0.05).Conclusion:The copies of MP-DNA in BALF is related to the clinical manifestation and inflammatory reaction of MPP in children.In the high MP-DNA copy group,the hospitalization time was longer,the heat peak was higher,the total course of fever and the duration of high fever were longer,the lung was prone to consolidation or atelectasis and had more pleural effusion,and extrapulmonary lesions and high agglutination condition were easy to occur.The inflammatory reaction in peripheral blood and lavage fluid in the high copy group was more severe than that in the low copy group.And the high copy group had certain reference significance for the diagnosis of RMPP.