| Research background and objective:Mycoplasma Pneumoniae(MP),one of the most common pathogens of respiratory infections,is an important cause of Community Acquired Pneumonia(CAP),and accounts for14.5%-40%of hospitalized children with pneumonia.In recent years,MP infection has presented many different characteristics,such as poor drug effect,younger infection age and the emergence of new detection methods.In the past,MP infection was thought to occur mostly in older children,but recently this characteristic is becoming less apparent and more infants are suffering from MP infection.It was previously thought that macrolides were effective against most MP infections,but in recent years,drug-resistant strains have increased,the effect of macrolides has become worse,and the incidence of RMPP(Refractory Mycoplasma Pneumoniae Pneumonia)has increased,as the incidence of RMPP in infants.In addition,MP can occur in semi-enclosed environments,such as schools and kindergartens.The clinical manifestations of MP infection are not special and also easily confused with viral infection.Therefore,early and accurate detection of MP is of great clinical significance for the diagnosis and treatment of MP infection.The commonly used clinical MP detection methods include serological detection,Fluorescence quantitative amplification of DNA and the simultaneous amplification and test(SAT).In recent years,nucleic acid detection has been included in the diagnosis of MP infection in the guidelines at home and abroad.In this paper,at the fever outpatient clinic,of 0 to 14 years old children’s throat swabs were acquired and tested by fluorescence quantitative of DNA,and swabs and venous blood of children in department of respiration were obtained and detected by fluorescence quantitative amplification of DNA,thermostatic amplification of RNA,MP culture and MP-IgM.The related clinical data were collected and statistical analysis was carried out on the results,aiming to compare the pros and cons of the fluorescence quantitative amplification of DNA and thermostatic amplification of RNA,explore the clinical correlation between MP load and situation of disease,so as to provide scientific basis for the diagnosis and treatment of MP infection for pediatric clinicians.Methods:(1)Study subjects were determined by inclusion criteria and exclusion criteria from children with respiratory tract infection aged 0-14 years who were admitted to the fever clinic.Oropharyngeal swabs were taken for each subject,fluorescence quantitative amplification of DNA was determined,and relevant clinical data and infection status of family members were recorded.(2)Study subjects were selected from hospitalized children in respiratory department through inclusion criteria and exclusion criteria.Three oropharyngeal swabs were collected on the first or second day after hospitalization for MP culture,fluorescence quantitative amplification of DNA and thermostatic amplification of RNA,and venous blood was extracted for MP-IgM.If MP culture was positive or two of the other three methods were positive,MP infection was considered.Before discharge,3 oropharyngeal swabs were collected again for children with MP infection,and the three tests were completed again.Relevant clinical data were recorded.The correlation between MP load and clinical conditions is explored.Since it was difficult to collect venous blood before discharge,no secondary detection of MP-IgM was performed.Prospective longitudinal comparison was made between three methods:fluorescence quantitative amplification of DNA,thermostatic amplification of RNA and MP culture.The assessment before the second test was as follows:clinical remission,normal body temperature,reduction or disappearance of lung rales,basically normal blood routine examination,and improvement of cough and other symptoms.Results:(1)There were 1025 valid samples from fever clinic:322 cases in spring,345 cases in summer,220 cases in autumn and 138 cases in winter.There were significant differences in MP detection rates among four seasons(χ~2=28.673,p(27)0.001).Cases in summer and autumn are more than that in winter and spring.The gender,age and infection degree of children with MP infection in four seasons has no significant difference(p(29)0.05).There were 392,399,234cases in less than two years old,two to five years old and more than five years old respectively.As to cases with MP infection,there were 19,70,74 cases in three age groups respectively.There were significant differences in three age groups(χ~2=326.000,p(27)0.001).(2)No students in the neighbor class were infected,students in the same class were easily infected,and members in the same family were very easily infected.In families with two children,one child is more likely to transmit MP infection to another child,while the older children are more likely to transmit MP to younger children.(3)There were 198(43.61%),196(43.17%),180(39.65%)and 139(30.62%)positive cases among 454 inpatients in fluorescence quantitative amplification of DNA,thermostatic amplification of RNA,MP culture and MP-IgM respectively.There were significant differences among four methods(χ~2=20.771,p(27)0.001).(4)In the second test of 209 inpatients with MP infection before discharge,148 cases were positive for MP culture,with a positive rate of 70.81%,14 cases(6.70%)changed from negative to positive,and 46 cases(22.10%)changed from positive to negative.The number of thermostatic amplification of RNA positive cases was 180,with a positive rate of 86.12%,27(12.92%)turned from positive to negative,and 11(5.26%)turned from negative to positive.The other two tests were both positive.There were 190 fluorescence quantitative amplification of DNA positive cases with a positive rate of 90.91%,among which 4(1.91%)changed from negative to positive and 12(5.74%)from positive to negative.The total positive rates of thermostatic amplification of RNA and fluorescence quantitative amplification of DNA decreased by 7.66%and 3.83%,respectively.By fluorescence quantitative amplification of DNA,67.5%of the positive samples showed a decrease in MP load and 32.5%showed an increase between the two tests.Conclusions:(1)The number of MP infected children is higher in summer and autumn than that in winter and spring in this hospital and MP infection in children less than 5 years of age is increasing.(2)The infectivity of MP is related to distance,and people in the same family and class are susceptible to infection so social distancing is recommended in crowded places.(3)The detection rate and accuracy of fluorescence quantitative amplification of DNA and thermostatic amplification of RNA were higher than that of MP-IgM and MP culture,and the detection results of fluorescence quantitative amplification of DNA and thermostatic amplification of RNA were highly consistent.(4)MP load were not parallel to the disease conditions of the children with MP infection. |
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