Epidemiologic analysis of Mycoplasma pneumoniae infection in children with acute respiratory tract infection

Objective To analyze the status and epidemiological characteristics of Mycoplasma pneumoniae (MP) infection in children with the acute respiratory infection (ARI). Methods From March 2011 to February 2016, a total of 111 321 cases of hospitalized children with ARI were selected as research subjects. Serum MP antibody in children with ARI was detected by passive agglutination method and immumofluorescence method. The infection rates of MP in children with ARI among different disease types, years, seasons, ages and genders were retrospectively analyzed and were analyzed by statistical methods. Results ①Among 111 321 cases of children with ARI, the infection rate of MP was 39.0% (43 411/111 321). There were statistical differences among the infection rates of MP in children with different disease types of ARI (χ2=1 197.0, P=0.000). And the infection rate of MP was the highest in children with pneumonia which was 44.5% (18 839/42 291), while it was lowest in children with upper respiratory tract infection which was 33.8% (17 965/53 158). However, the top two of ARI children with MP were children with pneumonia and upper respiratory tract infection which accounted for 43.4% (18 839/43 392) and 41.4% (17 965/43 417), respectively. ②The infection rate of MP in children with ARI in 2015 was 44.0% (16 922/38 479) which was higher than 39.4% (4 521/11 466) in 2011, 34.1% (5 521/16 192) in 2012, 36.9% (7 329/19 881) in 2013 and 36.1% (9 124/25 303) in 2014, and the differences were statistically significant (χ2=694.7, P=0.000). There were statistical differences among the infection rates of MP in children with ARI in spring, summer, autumn and winter during 2011 to 2015 (χ2=63.5, P=0.000; χ2=80.2, P=0.000; χ2=33.4, P=0.000; χ2=176.3, P=0.000; χ2=47.6, P=0.000). During 2011 to 2015, the seasonal peak of MP infection was winter in every year, and they were 46.0% (1 207/2 622), 38.6% (1 638/4 246), 39.7% (1 950/4 914), 40.3% (2 643/6 562) and 47.6% (4 945/10 399), respectively. ③The infection rate of MP was higher in children aged 6-14 years old (61.5%, 6 704/10 902) than those aged under 28 days old (2.2%, 49/2 214), aged 28 days to 1 year old (13.8%, 3 858/27 949), aged 1-3 years old (43.1%, 15 087/34 996) and aged 3-6 years old (50.3%, 17 719/35 260). There were statistical differences among the infection rates of MP in different age groups children with ARI (χ2=13 179.1, P=0.000). ④The infection rate of MP in girls was higher (45.8%, 20 017/43 746) than that in boys (34.6%, 23 400/67 575), and the difference was statistically significant (χ2=1 400.2, P=0.000). Conclusions In Nanning, MP infection occurs all through the year in children with ARI, and the infection rate in winter is the highest. The infection rate of MP in girls is higher than that in boys, and the infection rate in children aged 6-14 years old is higher than that of the children aged less than 6 years old. The clinical manifestations of MP infection are primary to pneumonia or upper respiratory infection. Key words: Child; Mycoplasma pneumoniae; Epidemiology; Respiratory tract infections, acute