title: Recurrent invasive pneumococcal disease in children: epidemiological, microbiological, and clinical aspects from a Danish 33-year nationwide survey (1980-2013).
abstract: BACKGROUND
  Pneumococcal diseases play a major role in human morbidity and mortality. We present the results of a Danish nationwide study of recurrent paediatric invasive pneumococcal disease (rIPD) focusing on the epidemiological, microbiological, and clinical aspects.
  
  
  METHODS
  All laboratory-confirmed cases of IPD in children aged 0-15 y were identified from the Neisseria and Streptococcus Reference Laboratory, Statens Serum Institut, Denmark for the period 1980-2013. rIPD was defined as isolation of Streptococcus pneumoniae from any normally sterile site ≥ 30 days after an initial positive culture. Clinical data were obtained for all children with rIPD.
  
  
  RESULTS
  Of all children with IPD, 2.4% (59/2418) experienced at least 1 episode of rIPD, and an underlying condition was documented in 39 (66%). Immune deficiency due to transplantation (n = 9) was the most common disease; however, anatomic abnormalities (n = 8), complement C2 deficiency (n = 4), and congenital asplenia (n = 3) were all registered more than once. No underlying disease was detected in 18 children (31%). Based on the serotype distribution of S. pneumoniae isolates in rIPD among children aged 0-5 y (n = 41), 51%, 66%, and 78% of the cases would have been covered by the 7-, 10-, and 13-valent pneumococcal conjugate vaccines, respectively.
  
  
  CONCLUSIONS
  Of children with an IPD episode, 2.4% experienced rIPD, and an underlying disease was documented in 66% of these children. Investigation of underlying conditions is essential in episodes of rIPD.
authors.affiliation: From the Neisseria and Streptococcus Reference Laboratory, Department of Microbiology and Infection Control, Statens Serum Institut , Copenhagen , Denmark.
authors.forename: Helene
authors.initials: H
authors.lastname: Ingels
authors.forename: Lotte
authors.initials: L
authors.lastname: Lambertsen
authors.forename: Zitta B
authors.initials: ZB
authors.lastname: Harboe
authors.forename: Hanne V
authors.initials: HV
authors.lastname: Marquart
authors.forename: Helle
authors.initials: H
authors.lastname: Konradsen
authors.forename: Jens Jørgen
authors.initials: JJ
authors.lastname: Christensen
authors.forename: Carsten
authors.initials: C
authors.lastname: Heilmann
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003718:Denmark / Q000453:epidemiology; D006801:Humans; D007223:Infant; D011008:Pneumococcal Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology*; D012008:Recurrence; D012189:Retrospective Studies; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification*