title: Pneumococcal bacterial load colonization as a marker of mixed infection in children with alveolar community-acquired pneumonia and respiratory syncytial virus or rhinovirus infection.
abstract: BACKGROUND
  The main aim of this study was to evaluate whether nasopharyngeal Streptococcus pneumoniae colonization in children with alveolar community-acquired pneumonia (CAP) and respiratory syncytial virus (RSV) or rhinovirus (RV) infection indicates a mixed lung infection.
  
  
  METHODS
  The nasopharyngeal secretions of 530 children with radiographically confirmed CAP were tested using the Luminex x TAG respiratory virus panel fast assay. Real-time polymerase chain reaction for the autolysin-A (LytA) and wzg (cpsA) genes of S. pneumoniae was performed on the RSV- and RV-positive samples.
  
  
  RESULTS
  Sixty-five of the 126 RSV-positive children (51.6%) were colonized with S. pneumoniae. Mean bacterial load was significantly higher in the patients with alveolar involvement (4.54±1.47 log10 DNA copies/mL vs. 3.75±1.62 log10 DNA copies/mL; P=0.04). Serotypes 5 and 19A were almost exclusively identified in the children with RSV and alveolar CAP, although the difference was statistically significant only for serotype 19A (P=0.03). Eighty-three of the 134 RV-positive children (61.9%) were colonized with S. pneumoniae and again mean bacterial load was significantly higher in the patients with alveolar involvement (4.21±1.37 log10 DNA copies/mL vs. 3.41±1.47 log10 DNA copies/mL; P=0.03). Serotypes 1, 5 and 19A were more frequently identified in the children with RV and alveolar CAP, although the difference was statistically significant only for serotype 5 (P=0.04).
  
  
  CONCLUSIONS
  In children with alveolar CAP and RSV or RV infection, the determination of nasopharyngeal pneumococcal bacterial load and identification of the serotypes can contribute to the diagnosis of mixed lung infection.
authors.affiliation: From the *Pediatric Clinic 1, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; and †Department of Epidemiology, Istituto di Ricerche Farmacologiche "Mario Negri"-IRCCS, Milan, Italy.
authors.forename: Susanna
authors.initials: S
authors.lastname: Esposito
authors.forename: Alberto
authors.initials: A
authors.lastname: Zampiero
authors.forename: Leonardo
authors.initials: L
authors.lastname: Terranova
authors.forename: Valentina
authors.initials: V
authors.lastname: Ierardi
authors.forename: Beatrice
authors.initials: B
authors.lastname: Ascolese
authors.forename: Cristina
authors.initials: C
authors.lastname: Daleno
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Prada
authors.forename: Claudio
authors.initials: C
authors.lastname: Pelucchi
authors.forename: Nicola
authors.initials: N
authors.lastname: Principi
mesh_terms: D058491:Bacterial Load; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D060085:Coinfection / Q000382:microbiology* / Q000821:virology; D017714:Community-Acquired Infections / Q000000981:diagnostic imaging / Q000382:microbiology* / Q000821:virology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009305:Nasopharynx / Q000382:microbiology; D010850:Picornaviridae Infections / Q000382:microbiology* / Q000821:virology; D011018:Pneumonia, Pneumococcal / Q000000981:diagnostic imaging / Q000382:microbiology* / Q000821:virology; D011024:Pneumonia, Viral / Q000000981:diagnostic imaging / Q000382:microbiology* / Q000821:virology; D011859:Radiography; D018357:Respiratory Syncytial Virus Infections / Q000382:microbiology* / Q000821:virology; D012136:Respiratory Syncytial Viruses / Q000302:isolation & purification; D012229:Rhinovirus / Q000302:isolation & purification; D013296:Streptococcus pneumoniae / Q000302:isolation & purification*