Study On The Etiology And Clinical Features Of Community Acquired Pneumonia In Children In Chengde From 2017 To 2018

Community acquired pneumonia(CAP)is one of the most common infectious diseases in children with high morbidity and mortality.CAP is usually caused by a variety of pathogens,including bacteria,viruses,atypical pathogens,etc.Due to various limiting factors such as climate,environment,region and detection methods,the pathogen spectrum of CAP has regional characteristics.Moreover,the pathogens of CAP itself are constantly changing.The emergence and spread of drug-resistant pathogens have accelerated.Meanwhile,with the progress of inspection technologies and methods,the more new pathogens have been discovered.In recent years,the proportion of severe and refractory cases in hospitalized children with CAP have increased significantly compared with the past,not only causes great pain to children,but also brings a huge economic burden to the family.Children,with unique physiological characteristics,make their conditions change rapidly.And there has a crossover in clinical manifestations of CAP,which caused by different pathogens..That makes more limited for clinical diagnosis from clinical manifestations.There are studies focus on children's CAP,but the results are not completely consistent.At present,there is no research on the CAP pathogens in chengde,therefore,it is particularly necessary to understand the distribution of CAP pathogens in this region.Objective:To understand the types and epidemiological characteristics of pathogens in hospitalized children with CAP in Chengde City;analyzing the distribution characteristics of various pathogens in different conditions and different ages in children,in order to summarize the characteristics of pneumonia caused by various pathogens,and provide reference for clinical work.Methods:From November 2017 to May 2018,333 pediatric patients hospitalized in Chengde Central Hospital for CAP were selected.All samples were determined by polymerase chain reaction(PCR)or Realtime-PCR to detect the specific DNA of pathogens(viruses,bacteria and atypical pathogens).The viruses included the influenza virus,arainfluenza virus,respiratory syncytial virus,human metapneumovirus,human bocavirus,human rhinovirus,human coronavirus,adenovirus.Staphylococcus aureus,Klebsiella pneumoniae,group A Streptococcus and Haemophilus influenzae were included in the bacteria group.The atypical pathogens were pneumonia mycoplasma,pneumonia chlamydia and eosinophilic lung legionella.The children were grouped according to PCR or RTPCR test results,severity of illness and age,the types of pathogens and the coinfections of each child were analyzed,and the clinical manifestations in children of different age groups and different disease groups were analyzed.Statistical analysis was performed using SPSS19.0.and enumeration datawere analyzed using chi-square test..Independent sample t test was used in measurement data in line with normal distribution,while non-parametric test was used for measurement data in line with abnormal distribution.Results:1.VirusThe detection rate of human partial lung virus,human bocavirus,adenovirus were 24.02%,6.61%,1.8%,respectively.respiratory syncytial and human coronavirus were both 0.30%,but influenza virus,parainfluenza virus and human rhinovirus were not detected.The single infection rate of human metapneumovirus was 88.75%,and the co-infection rate with another virus was 10.0%,among 7 cases were mixed with bocavirus and 1 case was mixed with adenovirus.The proportion of triple infection with other 2 viruses were 1.25%,which was mixed with human bocavirus and adenovirus.The single infection rate of human bocavirus was 63.64%,the double infection rate with human partial lung virus was 31.81%.The proportion of triple infection with other 2 viruses was 4.55%,which was mixed with human metapneumovirus and human bocavirus.The single infection rate of adenovirus was 66.67%,and the double infection rate was 16.67% with human metapneumovirus infection.The triple infection rate was 16.67%,which was related to human pneumovirus and human bocavirus.Moreover,the rate of virus detected was higher in autumn and winter(P<0.05).And the age distrubition was similar in the two groups(< 5 years old and ? 5 years old).The positive rate of virus was 45.0% in severe group,which was higher than the mild group with 27.99%(P < 0.05),there was no significant change in pathogen distribution structures between the two groups.Furthermore,the severe group children were older and had a higher fever peak.The duration of fever and hospitalization was significantly longer than the mild group(P<0.05).The proportion of neutrophils in severe group was higher than mild group,and the proportion of lymphocytes was lower than mild group(P<0.05).However,there was no significant difference in WBC count,CRP and LDH between the two groups.There was no significant difference between the severe group and the mild group in gender and the rales in pulmonary auscultation.2.BacteriaThe positive rate of bacteria was 78.09%,including Haemophilus influenzae(62.76%),group A Streptococcus(37.54%),Klebsiella pneumoniae(19.82%)and Staphylococcus aureus(6.00%).Neither Acinetobacter baumannii nor Pseudomonas aeruginosa were detected in all samples.Single Haemophilus influenzae infection accounted for 41.15%,mixed with other bacteria accounted for 58.85%,among which 46.89% were double infection,10.53% were triple infection and 1.44% were quadruple infection.The single infection rate of group A Streptococcus was 25.60%,mixed infection rate with other bacteria was 74.40%,among which 55.2% were double infection,16.8% were triple infection and 0.8% were quadruple infection.Single infection rate of Klebsiella pneumoniae was 15.15%,double,triple,quadruple infection rate were 54.55%,25.76%,2.4%,respectively.The proportion of single Staphylococcus aureus infection was 5.00%,35.00% was double infection,45.00% was triple infection and 15.00% was quadruple infection.In children younger than 5 years old,the positive rate of group A Streptococcus was 42.26%,and the mixed infection rate was 73.24%.The positive rate of Klebsiella pneumoniae was 19.39%,and the proportion of mixed infection was 84.38%.In children over 5 years old,the positive rate of group A Streptococcus was 32.73%,and the proportion of mixed infection was 75.93%.The proportion of mixed infection of group A Streptococcus and Klebsiella pneumoniae in children over 5 years old was significantly higher than that in children under 5 years old.t(P < 0.05).There was no significant difference in the proportion of mixed infection between the two groups(P > 0.05).There was no significant difference in pathogen composition between the severe group and the mild group.3.Atypical pathogensThe positive rate of Mycoplasma pneumoniae was 66.37%,and the Chlamydia pneumoniae was 7.81%.There was no Legionella pneumophila was detected.The positive rate of Mycoplasma pneumoniae in autumn and winter was significantly higher than spring(P < 0.05).The positive rate of Mycoplasma pneumoniae in children under 5 years old(59.52%),was significantly lower than over 5 years old chileren(73.33%,P < 0.05).The detection rate of Chlamydia pneumoniae was up to 25% in 12 years old children,and in other age groups were less than 25%.There was no significant difference between the mixed infection of mycoplasma pneumoniae and other pathogens in children between the two age groups.Among the children with Mycoplasma pneumoniae pneumonia,the median age was 7 years old in the severe group which was significantly higher than the mild group(P < 0.05).The fever peak in severe group was higher than mild group,and the duration of fever,cough and hospitalization were longer than mild group.The proportion of neutrophils in the severe group was significantly higher compared with the mild group,while the proportion of lymphocytes was lower than mild group,t.The distributions of white blood cell count,C-reactive protein and lactate dehydrogenase in the two groups were similar.There were no significant difference between the two groups in gender distribution,ragional distribution and lung rales.4.Comparison of clinical information between the CAP groups in severe group and mild groupThe age and fever peak of the children in the severe group were higher than those in the mild group,and the duration of fever,cough and hospitalization were significantly longer than mild group(P < 0.05).The WBC count and lymphocyte ratio were lower in the severe group.Neutrophil proportion and CRP level in the severe group were significantly higher than mild group(P < 0.05).There were no significant differences in LDH,gender,and the lung rales between the two groups.5.Comparison between PCR detection and serum examination of Mycoplasma pneumoniaeThe positive rate of Mycoplasma pneumoniae in serum examination was 51.05%,which was significantly lower compared with the PCR molecular detection(66.37%).Conclusion1.The pathogen of CAP in children in chengde city is mainly caused by pneumovirus,Haemophilus influenzae and Mycoplasma pneumoniae,and mixed infections exist.2.The positive rate of virus in CAP group was higher than mild group,but the majority of patients in both groups were infected with human metapneumovirus,and there was no difference in the composition of viral pathogen spectrum.The positive rate of bacteria in the two groups were similar,and there was no significant difference in the composition of bacterial pathogen spectrum.3.The age and fever peak of children with pneumonia in the severe group were higher than mild group,and the duration of fever,cough and hospitalization were significantly higher than mild group,while the WBC count and lymphocyte ratio were lower than mild group.The proportion of neutrophil and CRP level were higher than mild group.4.The viral infection of children in all age groups were both mainly caused by human metapneumovirus,and the viral pathogen spectrum was similar.The bacteria infections were dominated by Haemophilus influenzae,but the proportion of group A Streptococcus mixed with other bacteria and Klebsiella pneumoniae mixed with other bacteria was higher than those of children younger than 5 years old.Mycoplasma pneumoniae infection was mainly mixed with bacteria,but there was no significant difference in pathogen spectrum between the two groups.5.The PCR of pharyngeal swabs was a good reference in the etiological diagnosis of children's CAP.