Abstract: Objective To explore the relationship between the clinical phenotype and chest imaging of communityacquired pneumonia (CAP) with the mutation of Mycoplasma pneumoniae (MP) 23 S rRNA A 2063 G gene. Methods A total of 142 children with CAP hospitalized from March 2019 to March 2020 were selected as the research objects. The chest imaging examinations were scored by the pneumonia chest radiograph absorption evaluation scale. At the same time, the blood routine, CRP, MPIgG, MPIgM, MP polymerase chain reaction of throat swab and other laboratory tests were performed. The children were divided into MPP group and non-MPP group (N-MPP) according to the pathogen results. For MP-PCR positive children, the 23 S rRNA A 2063 G site was further detected. The children were divided into the variant group (G-MPP) and the non-variant group (A-MPP) according to whether there is A2063G mutation, and the differences in clinical phenotypes between the two groups were compared. Results In a total of 142 children included, there were 78 males and 64 females with a median age of 5 years (range from one month to 14 years). The age difference between MPP group and N-MPP group was statistically significant (P< 0 . 05 ). Twenty-seven patients in the MPP group had 23 S rRNA A 2063 G mutation and a variation rate was 30 . 34 %. Compared with A-MPP group, G-MPP group had longer fever duration, longer hospital stay, higher incidence of hypoxemia, and higher chest imaging scores in children with hypoxemia, and the differences were statistically significant (all P< 0 . 05 ). Conclusions The children with G-MPP had long fever duration, a longer hospital stay, a higher incidence of hypoxemia, and a higher chest imaging score in children with hypoxemia. However, chest imaging scores may not be used to indicate whether drug-resistant MP infection happens.

Key words: community acquired pneumonia; mycoplasma pneumoniae pneumonia; chest X-ray plain film; drug resistance gene mutation; child