Objective To investigate Mycoplasma pneumoniae （MP） infection and macrolide resistance of hospitalized children in Ningbo Area in 2019‒2021.

Methods A total of 6 782 respiratory throat swab specimens were collected from hospitalized pediatric patients with pneumoniae， admitted in Ningbo Women and Children's Hospital from January， 2019 to December 2021. MP and its mutations in 23S rRNA were detected by real-time polymerase chain reaction.

Results Among 6 782 respiratory throat swab specimens from 2019‒2021， 1 290 cases （19.02%） were MP positive， and the positive rate decreased year by year （P<0.05）. The positive rate in 2019 was 28.12%， higher than that in 2020 （7.16%） and 2021 （5.16%） （all P<0.017）. The mutation of 23S rRNA occurred in 947 cases， with a mutation rate of 73.41%. The mutation rate in 2020 was 84.04%， higher than that in 2019 （73.01%） and 2021 （66.23%）. The differences of positive rate and mutation rate in different seasons were significant （P<0.05） （all P<0.008）. The positive rate was the highest in summer （25.00%）， and the mutation rate was the highest in winter （78.89%）. The positive rate of female children was 20.52%， higher than that of male children （17.82%） （P<0.05）， and the mutation rates of female and male children were 74.93% and 71.77% （P>0.05）， respectively. The difference of positive rate among the different age was significant （P<0.05）. The positive rates in the 5‒ and 8‒ years groups were 27.24% and 26.38%， higher than those in the 1‒ and 2‒ years groups， respectively. The difference of mutation rate among the four groups in age was not significant （P>0.05）.

Conclusion The infection rate of MP in children decreases in Ningbo Area from 2019 to 2021. MP infection may be related with gender， seasonal distribution， age， and the resistance rate of MP to macrolide is high.