| BackgroundMycoplasma is a kind of cell wall-free prokaryote and can pass a filter paper. Among the dozens of Mycoplasma in nature, Mycoplasma pneumonia(M. pneumoniae) is confirmed as a major cause of community acquired pneumonia(CAP). Because of the special attachment tip, MP is easy to bind to respiratory tract epithelial cells and establish an infection. MP infections are found in approximately40%of the children infected with CAP, and of these,1/5of the patients require hospitalization. Clinical differential diagnosis of M. pneumoniae infection is difficult because clinical and radiography image manifestations are similar to those of infections with other pathogens. Because of the absence of cell wall, this organism is insensitive to P-lactam antibiotics, which has brought challenges to the pediatrician for empirical therapy. It is possible to delay the disease progression if neglecting of MP infection. MP is still one of serious respiratory diseases pathogens which are threatening children’s health.MP infection is endemic in larger communities of the world with cyclic epidemics every3to5years. Patients or carriers are the source of infection. MP can be transmitted through droplets or aerosols. The incubation period of infection is generally1to3weeks. In recent years, the prevalence of MP infection showed a trend of increasing stage, and the susceptible age was extended to younger children more than5-15years old. Because of increasing cases with extra-pulmonary manifestation as the first clinical symptom, the misdiagnosis of MP infection could cause great damage to the health of children. Among the epidemiological studies of MP, seasonal differences in MP infection among different areas were significant. The relationship between gender and MP infection was inconclusive. Although the school-age children for high-risk age MP infection had been a consensus, infections among the younger children could not be ignored. In addition, little is known about the association between the prevalence of MP and meteorological factors. Large samples of continuous dynamic monitoring data studies are still needed.Four hospitals in Ningbo were selected as sentinel. Serum samples of outpatient and inpatient children were tested for MP IgM antibody (MP-IgM) for5years. Meteorological data of the corresponding time period were collected and analyzed.Objective1To obtain the epidemiological characteristics of M. pneumoniae infections among hospitalized children.2To study the relationships between M. pneumoniae infections and meteorological factors.MethodA total of109,901cases were collected according to the inclusion and exclusion criteria from4hospitals children in Ningbo from2010to2014. Serum samples were tested for MP-IgM by Passive Agglutination Method. Positive rates of MP among different hospitals, years, seasons, treatment categories (outpatient and inpatient), sex and age groups were compared by Pearson chi-square test. Meanwhile, daily mean temperature and relative humidity were collected from meteorological bureau. Correlation between MP infection and the meteorological factors were analyzed by Pearson correlation analysis. All analyses were done in SPSS19.0(SPSS, Inc., Chicago, IL, USA). Result1Epidemiological characteristics of MP infections.1.1Time distribution of MP infectionsThe positive rates of MP from2010to2014were19.4%,22.0%,27.8%,27.4%and29.4%respectively. The positive rates increased with increasing year(χ2=562.92, P <0.001, test for linear trend). The positive rates of MP were significant differences among different seasons(χ2=75.59, P<0.001). Positive rate of autumn was higher than that of winter(χ2=9.19, P=0.002) and spring(χ2=60.76, P<0.001). Positive rate of summer was higher than that of winter(χ2=53.67, P<0.001) and spring(χ2=7.05, P=0.008). Positive rate of winter was higher than that of spring(χ2=22.08, P<0.001).1.2Population distribution of MP infectionsThe MP positive rates of boys and girls were22.6%and30.5%respectively. The MP positive rate of girls was significant higher than that of boys(χ2=895.74, P<0.001). Positive rates of infancy, toddler, preschool and school age children were4.0%,19.0%,30.1%and39.7%respectively. The positive rates of MP increased with increasing age(χ2=6988.28, P<0.001, test for linear trend). The positive rate of outpatient children was significant higher than that of inpatient children(χ2=1365.69, P<0.001). The positive rates of MP in outpatient children and inpatient children were21.0%and31.3%respectively.1.3Epidemiological characteristics of double infection with MP and CPThe double infection rate of MP and CP was1.8%. The double infection rates decreased with increasing year(χ2=90.14, P<0.001, test for linear trend), The double infection rates were significant differences among different seasons(χ2=40.70, P<0.001). The double infection rate of autumn was the highest in4seasons. The double infection rate of girls was significant higher than that of boys(χ2=37.01, P<0.001) and increased with increasing age(χ2=283.54, P<0.001, test for linear trend). The double infection rate of outpatient children was significant higher than that of inpatient children(χ2=24.16, P<0.001).2. Relationships between MP infections and meteorological factors. There was a positive correlation between positive rates of MP and weekly average temperature (r=0.210, P<0.05) and monthly average temperature(r=0.335, P<0.05). There existed no correlation between daily positive rates of MP and average relative humidity (P>0.05). There were positive correlation between positive rates of MP and lagged average weekly temperature (Iagl-lag8)(P<0.05), and the correlation coefficients were0.216、0.241、0.258、0.267、0.27、0.297、0.306and0.312respectively. There were positive correlation between positive rates of MP and lagged average daily temperature (lag0-lag7)(P<0.05), and the correlation coefficients were0.062、0.066、0.071、0.085、0.096、0.105、0.103and0.100respectively.Conclusions1Epidemiological characteristics of MP infections were as follow:From2010to2014, the infection rates of MP increased year by year. MP was prevalent in summer and autumn. The infection rates of MP increased with increasing age. MP infection rate of girls was higher than that of boys. The positive rate of MP in outpatient children was higher than that of inpatient children. The double infection of MP and CP rates decreased with increasing year.2Higher temperatures could increase the MP infection. There existed a lagged effect of temperature on MP infection. |
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