Epidemiological Characteristics Of Mycoplasma Pneumoniae Infection In Children In Suzhou Area And Its Correlations With Climatic And Environmental Factors

Objective:To study the prevalence of Mycoplasma pneumoniae(MP)infection in hospitalized children in Suzhou from 2013 to 2018.To explore the correlation between climate and environment factors and MP infection in children,and to establish an early warning model to prevent MP infection.Method:MP-DNA and human boca virus(Human boca virus,hBoV)were detected by polymerase chain reaction(PCR)for children hospitalized with respiratory infections in Suzhou from 2013 to 2018,and we use quantitative method to detect the serum MP IgG,using semi-quantitative method to detect the serum MP IgM,direct immunofluorescence for respiratory syncytial virus(Respiratory syncytial virus,RSV),influenza virus A,B(Influenza virus type A?B,?A??B),parainfluenza virus type ?????(Parainfluenza virus type ???,Pinf ???)and adenovirus(Adenovirus,ADV)in the sputum,RT-PCR for detecting human meta-pneumoniae virus(Human meta-pneumoniae virus,hMPV)and human rhinovirus(Human rhinovirus,hRV),and sputum culture to detect bacteria,respectively;At the same time,we collected the monthly average density of air pollutants(PM2.5,PM10,SO2,NO2,CO,O3)and climate factor parameters(monthly mean temperature,monthly average humidity,monthly precipitation,monthly sunshine hours,monthly average wind speed)from 2013 to 2018 in Suzhou.Linear regression and stepwise regression methods are used to analyze the associations between MP and climate factors.Finally,an early warning model was established based on the data from 2013 to 2017 and predicted the trend in 2018.Result:Multi-etiological tests were performed on 10,916 children admitted to the Department of Respiratory Diseases in Children's Hospital of Soochow University from 2013 to 2018,and the detection rate of MP was 32.79%.The children were divided into five groups according to age,including 28 days to 6 months,7 to 12 months,13 to 36 months,37 to 60 months,and>60 months.The detection rate of MP in each groups were 9.34%,24.00%,40.81%,53.05%,and 70.25%.The detection rate of MP was the highest in the 60-month-old group.And with the increase of age,the detection rate of MP showed an increasing trend(?2=2208.031,P<0.001).Among the 10916 children enrolled,there were 6738 males and 4178 females.The MP detection rate of male children was 29.16%,the MP detection rate of female children was 38.63%,and the MP detection rate of female children was higher than that of male children(?2=104.905,P<0.001).The detection rate of MP in four seasons is different in six years.The detection rate in spring is 26.85%,the detection rate in summer is 38.28%,the detection rate in autumn is 38.29%,and the detection rate in winter is 27.12%.The detection rate of MP in summer and autumn is higher than that in winter and spring(?2=158.209,P<0.001).From 2013 to 2018,the detection rate of MP was 45.22%,31.06%,31.73%,41.80%,24.99%and 21.80%,respectively.2013 and 2016 are the peak years of MP epidemic(?2=351.328,P<0.001).The detection rate of MP is different among different months.The top three MP average detection rates are:August,July,and September.The positive detection rate is highest in August.The last three MP average detection rates were:March,February,and April,and the lowest positive detection rate was in March(?2=223.405,P<0.001).The detection rate of MP is different among different diseases.The highest rate shows in lobar pneumonia,followed by interstitial pneumonia,bronchitis,bronchopneumonia,upper respiratory infection,severe pneumonia,and bronchiolitis(?2=1246.678,P<0.001).There are differences in MP detection rates among children of different age groups.Upper respiratory tract infection and bronchitis have the highest MP detection rate among children aged 37-60 months,and bronchiolitis has the highest MP detection rate among children aged 13-24 months,as well as bronchial pneumonia,lobar pneumonia,and severe pneumonia were the highest MP detection rates among children older than 60 months(P<0.001).The detection rate of MP in the interstitial pneumonia group has no statistical significance among all age groups(P>0.05).The detection rate of MP in children with different respiratory tract infections is different in each age group.Among children aged from 28 days to 12 months,the MP detection rate of interstitial pneumonia is the highest(P<0.01).Among children older than 12 months,lobar pneumonia has the highest MP detection rate(P<0.001).Among 3579 children with MP infection,MP infection alone accounted for 69.10%,MP and virus mixed infection accounted for 20.40%,MP and bacterial mixed infection accounted for 7.30%,MP,virus,bacteria mixed infection accounted for 3.20%.The top three pathogens for MP mixed virus infection are:rhinovirus(HRV)10.98%,respiratory syncytial virus(RSV)5.70%,and boca virus(HBoV)4.25%.The top three bacterial pathogens co-infected with MP are Streptococcus pneumoniae(SP)8.07%,Moraxella catarrhalis(MC)1.06%,Haemophilus influenzae(HI)1.01%.Pairwise correlation analysis found that MP infection rate in children had a weak positive correlation with monthly mean temperature(r=0.418,P<0.001).An autoregressive average sliding model based on monthly mean temperature was used to predict MP infection(R2=0.185,BIC=4.881,P<0.001).Pairwise correlation analysis found that MP infection in children was negatively correlated with NO2 and CO.Multivariate stepwise regression analysis was used to show that MP infection was negatively correlated with CO(r=0.549,P<0.001).An autoregressive integrated moving average(ARIMA)model based on CO was used to predict MP infection(R2=0.261,BIC=4.784,P<0.001).Conclusions:(1)The epidemic peak of MP infection in children in Suzhou area occurred all over the year from 2013 to 2018.The epidemic season is mainly in summer and autumn.The highest detection rate in August.The detection rate of MP increased with the age.And the detection rate was highest in the group over 5 years old,and also higher in female children than male children.(2)MP is one of the most important pathogens in children with bronchiolitis aged 1-2 years,and also is the main pathogen of lobar pneumonia.Streptococcus pneumoniae and rhinovirus are the main pathogens in children co-infected with MP.(3)Climatic factors and environmental factors are related to MP detection rate in hospitalized children.(4)An early warning model based on environmental climatic factors can be established for clinical application to prevent and control mycoplasma infection.