Study On Upper Respiratory Tract Colonization In 1000 Healthy Children Aged 0-6 Years

BackgroundThe respiratory system is directly connected to the external environment,and the upper respiratory tract is the most common site of microbial colonization,which is sojourned by a variety of symbiotic bacteria and potential bacterial pathogens.Bacterial colonization in the respiratory tract refers to the status of bacteria that persist in airway mucosal epithelial cells or mucous secretions without host adverse reactions.Bacterial colonization is not yet an infection,but the most important source and risk factor for infection.as the largest mucosal system of the body in direct contact with the external environment,bacterial colonization was detected within 5 minutes after birth.respiratory microecosystem is affected by various self and environmental factors,in the process of dynamic change,children are the key period for the development of respiratory flora,and the colonization of microorganisms in early life can affect the susceptibility,severity and long-term prognosis of respiratory diseases.At present,with the acceleration of urbanization,the change of living environment,the aggravation of air pollution,the increase of disease severity and complexity,the development of medical technology,the extensive use of antimicrobial agents,the vaccination(pneumococcal vaccine,Haemophilus influenzae type b vaccine)and various invasive operations,the change of surface environment of epithelial cells makes pathogenic bacteria adhere to the mucosa of oropharyngeal mucosa and resist the defense mechanism.Because of its unique upper respiratory physiological characteristics,children are a high incidence of bacterial colonization and a source of transmission of respiratory pathogens in the community.Children's respiratory diseases remain one of the leading causes of children's hospital visits and deaths worldwide,so it is particularly important to understand the bacterial colonization of children upper respiratory tract.Foreign countries used 16SrDNA sequencing technology for Respiratory microbiota in healthy children,but the specificity was low and the testing instrument was expensive.in this study,multiple media probe melting curve analysis(multiple fluorescence pcr technique)with short time consuming,high specificity and relatively low price was used to understand bacterial colonization in upper respiratory tract of healthy children aged 0-6 years in the area.ObjectiveExplore the characteristics of upper respiratory tract colonization bacteria in healthy children aged 0-6 years,understand the relationship between upper respiratory tract colonization bacteria and age,sex,season and hib vaccination in healthy children aged 0-6 years,and provide reference for early treatment and prevention of respiratory diseases in children.MethodsFrom july 2018 to july 2019,1000 healthy children were inoculated in outpatient clinic of the third affiliated hospital of Zhengzhou university.According to age,the children were divided into baby group(1?<12 months),infant group(12?<36months),preschool group(36?<72months),and pharyngeal swabs were collected by professionals before vaccination.Put into hanks equilibrium salt solution,timely inspection,if 24 hours cannot be submitted for inspection-20.00?refrigerated.At present,16s dna sequencing technology and real-time fluorescence PCR technology are used to detect respiratory tract colonization bacteria in healthy children.In this study,the single tube was used to detect 15 colonization bacteria(Including Haemophilus influenzae,Streptococcus pneumoniae,Staphylococcus epidermidis,Moraxelle catarrhalis,Staphylococcus epidermidis,Mlicrococcus scarlatinae,Klebsiella,Acinetobacter baumannii,Aspergillus fumigatus,Candida albicans,Legionella aeruginosa,Pseudomonas aeruginosa,Escherichia coli,Cryptococcus,Bacillus pertussis).The data were entered and analyzed by the microsoft excel 2007 software package.The detection results were expressed as percentage(%);The data were statistically analyzed by spss21.0,statistical software using ?2 or Fisher's exact test,?=0.05 as test level.Results1.Total detection of bacteria in upper respiratory tractAmong the 1000 samples included in the study,402 samples were identified by multiplex fluorescence PCR detection method,with a total detection rate of 40.2%.There were 289 single-planted bacteria with a detection rate of 28.9%and 113 mixed bacterial with a detection rate of 11.3%,and mixed colonization was dominated by two bacteria mixed colonization,a total of 83 cases were detected,among which the detection rate of mixed colonization of streptococcus pneumoniae and haemophilus influenzae was the highest,and the mixed colonization of streptococcus pneumoniae and katamura was the second.The detection rate of Haemophilus influenzae was the highest,16.3%;the detection rate of Streptococcus pneumoniae was 15.6%,followed by the detection rate of Streptococcus pneumoniae;the detection rate of Camorra was 5.3%;the detection rate of Staphylococcus aureus was 5.9%;the detection rate of Staphylococcus epidermidis was 3.3%;the detection rate of Acinetobacter was 2.3%;the detection rate of Streptococcus pyogenes was 2.2%;the detection rate of Kleb pneumoniae was 1.8%;the detection rate of Pseudomonas aeruginosa,Escherichia coli,Cryptococcus,Bacillus pertussis and Aspergillus fumigatus was not detected.2.Detection of bacteria in upper respiratory tract in healthy children of different age groupsIn this study,284 cases were found in the baby group,with a positive rate of 35.6%,of which 28.5%was found for the single-species;the detection rate for the mixed-species(7.0%)was lower than that of the infant group and preschool group,with a statistically significant comparison between groups(P<0.05).compared with other age groups,baby group had the highest detection rate of Staphylococcus and statistically significant(P<0.01).There were 322 cases in the infant group with a positive rate of 40.4%,and the detection rate of Staphylococcus aureus in this group was the same as that in the preschool group,which was higher than that in the infant group.A total of 394 cases were detected in the preschool group,with a positive rate of 44.2%.among them,the detection rate of Haemophilus influenzae,Streptococcus pneumoniae and Streptococcus pyogenes and Klebsiella pneumoniae was higher than that of the infant group(P<0.05).3.Detection of bacteria in upper respiratory tract in healthy children with different genderIn this study,a total of 521 healthy men were detected,with a positive rate of 38.9%in 203,and 41.5%in 479 women.4.Detection of bacteria in upper respiratory tract in healthy children in different seasonsIn this study,164 cases were tested in spring with a positive rate of 36.5%;385 cases in summer with a positive rate of 33.7%;207 cases in autumn with a positive rate of 47.3%;and 121 cases in winter with a positive rate of 44.6%.the study showed that the detection rate of fixed bacteria in respiratory tract was different in different seasons,and the detection rate of fixed bacteria in autumn and winter was higher than that in spring and summer(P=0.004).Among them,the rate of mixed colonization in autumn was higher than that in other seasons(P<0.01);the rate of detection of Staphylococcus aureus in summer was higher than that of other seasons(P<0.05);the rate of detection of Candida albicans and Klebsiella pneumoniae was the highest in summer(P<0.01);the rate of detection of Haemophilus influenzae in autumn and winter was higher than that in other seasons(P<0.01);Candida albicans and Klebsiella pneumoniae had the highest detection rate in autumn,and the difference was statistically significant(p<0.01);No seasonal differences in Streptococcus pneumoniae,Staphylococcus epidermidis,Acinetobacter baumannii,Streptococcus pyogenes,etc.5.Effect of Hib vaccination on upper respiratory bacteria in healthy childrenIn this study,180 of the 1000 subjects were vaccinated against Hib and 506 against hib,of which 314 were ominous about Hib vaccination.The positive rate was 33.3%in the inoculated group and 42.1%in the unvaccinated group.the detection rate of respiratory tract fixed bacterial and mixed fixed bacterial in the Hib vaccine group was lower than that in the untreated hib vaccine group,and the difference between groups was statistically significant(P<0.05).Detection rates of Streptococcus pneumoniae,Haemophilus influenzae,Cataract Mora and Streptococcus pyogenes were lower than those of hib vaccine group.Conclusions1.The upper respiratory tract colonization bacteria in 1000 healthy children aged 0-6 years were mainly Haemophilus influenzae,Streptococcus pneumoniae,Staphylococcus aureus,and Moraxelle catarrhalis.2.The detection rate of bacterial colonization of upper respiratory tract increased with age.3.The detection rate of fixed bacteria in different seasons was different,and the detection rate of fixed bacteria in autumn and winter,Haemophilus influenzae,Katamora and mixed colonization was higher than that in other seasons,while Staphylococcus aureus in summer was higher than that in other seasons.4.The bacteria detection was decresed after Hib vaccination.