Infection And Coinfection Patterns Of Community Acquired Pneumonia In China

Background: Community-acquired pneumonia(CAP)is defined as infectious parenchymal inflammation of the lung acquired outside the hospital,including pathogen infection with a clear incubation period after the onset of pneumonia in the incubation period after admission.CAP is a major cause of hospitalization and death,and leads to a huge burden of health care costs.The estimated worldwide incidence of CAP varies between 1.5 to 14 cases per 1000 person-years,and this is affected by geography,season,and population characteristics.The incidence rate of CAP in children below 5 years old is 34–40 cases per 1000 person-years in Europe and North America and 65.8 cases per1000 person-years in China;the incidence rate of CAP in hospitalized adults in the United States is 24.80 cases per 10000 person-years.In China,the incidence is 2.40–14.98 cases per 1000 person-years in people aged≥18 years.No study was designed to comprehensively assess infection and co-infection patterns of CAP in patients,which was often restricted by inconsistent case definitions for CAP,different testing methods,and a limited set of target pathogens in samples.We aimed to explore the causal and epidemiological characteristics by age,to better describe patterns of CAP and their association with severe disease.Methods: National surveillance of CAP was conducted through a network of hospitals in 30 provinces in China from 2009?2020 inclusive.Demographic data,clinical symptoms and signs,laboratory indicators and clinical outcomes of patients meeting the CAP case definition were collected,and respiratory specimens were collected for all enrolled CAP patients and tested for up to 14 common respiratory pathogens(IFV,RSV,HPIV,HAd V,HMPV,HCo V,HBo V,P.aeruginosa,K.pneumoniae,S.aureus,S.pneumoniae,H.influenzae,and M.pneumoniae).Descriptive statistical methods were used to analyze the epidemiological characteristics,infection and co-infection of CAP and SCAP patients by age group,gender,case type and season of infection.With 14 clinical symptoms(fever,cough,expectoration,sore throat,tachypnea,dyspnea,rhinorrhea,chest pain,headache,fatigue,abdominal pain and diarrhea)as explanatory variables and age,gender and season of infection as correction variables,univariate and multivariate logistic regression were used to analyze the clinical characteristics associated with different pathogens.Clinical outcomes,including SCAP,were investigated with respect to age and patterns of infections/coinfections by performing binary logistic regression and multivariate analysis.Chi-square test or Fisher’s exact test was used to compare the differences in the positive rates and coinfection rates of different pathogens between before the COVID-19 pandemic(2009?2019)and during the COVID-19 pandemic(2020).Results: A total of 18 807 CAP patients(20.05% with SCAP)were enrolled.Bacterial infection was more frequently found than viral infection in the adults(18?60years)and elderly(>60 years),viral detection was more frequently found in children(≤5 years),while viral and bacterial positive rates were comparable for adolescents(6?17 years).For both children(≤5 years)and the elderly(>60 years),a higher overall rate of viral and bacterial infections,as well as viral-bacterial coinfection were shown in patients with SCAP over non-SCAP.For adults,however,only a higher rate of bacterialbacterial coinfection was observed.The most frequent pathogens associated with SCAP were RSV(21·30%)and S.pneumoniae(12·61%)among children,IFV(9.89%)and M.pneumoniae(13.79%)among adolescents,IFV(8.37%)and K.pneumoniae(11.75%)among adults,and IFV(10·94%)and P.aeruginosa(15·37%)among the elderly.Positive rates of most tested pathogens decreased during 2020 compared with2009-2019 period,with the exception of RSV,P.aeruginosa,and K.pneumoniae.Multivariate analyses,showed SCAP was significantly associated with infection with HAd V,HRV,K.pneumoniae,or coinfection of RSV-H.influenzae or RSV-S.aureus in juveniles(<18 years),and significantly associated with infection with P.aeruginosa,K.pneumoniae,S.pneumoniae,or P.aeruginosa-K.pneumoniae coinfection in adults≥18years.Conclusions: Both prevalence and infection pattern of respiratory pathogens differed between SCAP and non-SCAP in an age dependent manner.This suggests potential advantages to age-related strategies for vaccine schedules,as well as clinical diagnosis,treatment and therapy.