title: Comparison of the frequency of bacterial and viral infections among children with community-acquired pneumonia hospitalized across distinct severity categories: a prospective cross-sectional study.
abstract: The comparison of the frequencies of bacterial and viral infections among children with community-acquired pneumonia (CAP) admitted in distinct severity categories, in an original study, is lacking in literature to-date. We aimed to achieve this goal.
  
  
  
  Children aged 2-59-months-old hospitalized with CAP were included in this prospective study in Salvador, Brazil. Clinical data and biological samples were collected to investigate 11 viruses and 8 bacteria. Severity was assessed by using the World Health Organization criteria.
  
  
  
  One hundred eighty-one patients were classified as "non-severe" (n = 53; 29.3 %), "severe" (n = 111; 61.3 %), or "very severe" (n = 17; 9.4 %) CAP. Overall, aetiology was detected among 156 (86.2 %) cases; viral (n = 84; 46.4 %), bacterial (n = 26; 14.4 %) and viral-bacterial (n = 46; 25.4 %) infections were identified. Viral infection frequency was similar in severe/very severe and non-severe cases (46.1 % vs. 47.2 %; p = 0.9). Pneumococcal infection increased across "non-severe" (13.2 %), "severe" (23.4 %), and "very severe" (35.3 %) cases (qui-squared test for trend p = 0.04). Among patients with detected aetiology, after excluding cases with co-infection, the frequency of sole bacterial infection was different (p = 0.04) among the categories; non-severe (12.5 %), severe (29.3 %) or very severe (55.6 %). Among these patients, sole bacterial infection was independently associated with severity (OR = 4.4 [95 % CI:1.1-17.6]; p = 0.04) in a model controlled for age (OR = 0.7 [95 % CI:0.5-1.1]; p = 0.1).
  
  
  
  A substantial proportion of cases in distinct severity subgroups had respiratory viral infections, which did not differ between severity categories. Bacterial infection, particularly pneumococcal infection, was more likely among severe/very severe cases.
authors.affiliation: Bahiana School of Medicine, Bahiana Foundation for Science Development, Salvador, Bahia, Brazil.
authors.forename: Amanda C
authors.initials: AC
authors.lastname: Nascimento-Carvalho
authors.affiliation: Department of Paediatrics, Turku University and University Hospital, Turku, Finland.
authors.forename: Olli
authors.initials: O
authors.lastname: Ruuskanen
authors.affiliation: Department of Paediatrics, Federal University of Bahia School of Medicine, Salvador, Bahia, Brazil. nascimentocarvalho@hotmail.com.
authors.forename: Cristiana M
authors.initials: CM
authors.lastname: Nascimento-Carvalho
mesh_terms: D001938:Brazil / Q000453:epidemiology; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000453:epidemiology / Q000382:microbiology; D003430:Cross-Sectional Studies; D005260:Female; D006760:Hospitalization; D006801:Humans; D016015:Logistic Models; D008297:Male; D018410:Pneumonia, Bacterial / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D011024:Pneumonia, Viral / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D011446:Prospective Studies; D012720:Severity of Illness Index
keywords: Acute respiratory infection; Lower respiratory tract infection; Lung disease; Respiratory viruses; Severity assessment