title: Molecular Detection of Streptococcus pneumoniae on Dried Blood Spots from Febrile Nigerian Children Compared to Culture.
abstract: BACKGROUND
  Nigeria has one of the highest burdens of pneumococcal disease in the world, but accurate surveillance is lacking. Molecular detection of infectious pathogens in dried blood spots (DBS) is an ideal method for surveillance of infections in resource-limited settings because of its low cost, minimal blood volumes involved, and ease of storage at ambient temperature. Our study aim was to evaluate a Streptococcus pneumoniae real-time polymerase chain reaction (rt-PCR) assay on DBS from febrile Nigerian children on Whatman 903 and FTA filter papers, compared to the gold standard of culture.
  
  
  METHODS
  Between September 2011 to May 2015, blood was collected from children 5 years of age or under who presented to six hospital study sites throughout northern and central Nigeria with febrile illness, and inoculated into blood culture bottles or spotted onto Whatman 903 or FTA filter paper. Culture and rt-PCR were performed on all samples.
  
  
  RESULTS
  A total of 537 DBS specimens from 535 children were included in the study, of which 15 were culture-positive for S. pneumoniae. The rt-PCR assay detected S. pneumoniae in 12 DBS specimens (2.2%). One positive rt-PCR result was identified in a culture-negative specimen from a high-risk subject, and two positive rt-PCR results were negative on repeat testing. Six culture-confirmed cases of S. pneumoniae bacteremia were missed. Compared to culture, the overall sensitivities of Whatman 903 and FTA DBS for detection of S. pneumoniae were 57.1% (95% CI 18.4-90.1%) and 62.5% (95% CI 24.5-91.5%), respectively. Nonspecific amplification was noted in an additional 22 DBS (4.1%). Among these, six were positive for a non-S. pneumoniae pathogen on culture.
  
  
  CONCLUSIONS
  Rt-PCR was able to detect S. pneumoniae from clinical DBS specimens, including from a culture-negative specimen. Our findings show promise of this approach as a surveillance diagnostic, but also raise important cautionary questions. Several DBS specimens were detected as S. pneumoniae by rt-PCR despite growth of a non-S. pneumoniae pathogen on culture. A precise definition of what constitutes a positive result is required to avoid falsely over-identifying specimens.
authors.affiliation: Division of Pediatric Infectious Diseases and Immunology, University of Minnesota Masonic Children's Hospital, Minneapolis, Minnesota, United States of America.|Center for Infectious Diseases, Microbiology and Translational Research, Minneapolis, Minnesota, United States of America.
authors.forename: Pui-Ying
authors.initials: PY
authors.lastname: Iroh Tam
authors.affiliation: Center for Infectious Diseases, Microbiology and Translational Research, Minneapolis, Minnesota, United States of America.
authors.forename: Nelmary
authors.initials: N
authors.lastname: Hernandez-Alvarado
authors.affiliation: Division of Pediatric Infectious Diseases and Immunology, University of Minnesota Masonic Children's Hospital, Minneapolis, Minnesota, United States of America.|Center for Infectious Diseases, Microbiology and Translational Research, Minneapolis, Minnesota, United States of America.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Schleiss
authors.affiliation: Department of Paediatrics, Aminu Kano Teaching Hospital, Kano, Nigeria.
authors.forename: Fatimah
authors.initials: F
authors.lastname: Hassan-Hanga
authors.affiliation: Department of Paediatrics, Federal Medical Center, Keffi, Nasarawa, Nigeria.
authors.forename: Chuma
authors.initials: C
authors.lastname: Onuchukwu
authors.affiliation: Department of Paediatrics, Nyanya General Hospital, Abuja, Nigeria.
authors.forename: Dominic
authors.initials: D
authors.lastname: Umoru
authors.affiliation: Department of Pediatrics, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Obaro
mesh_terms: D001431:Bacteriological Techniques; D002675:Child, Preschool; D059788:Dried Blood Spot Testing / Q000379:methods*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009549:Nigeria; D011008:Pneumococcal Infections / Q000097:blood / Q000175:diagnosis*; D060888:Real-Time Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D013296:Streptococcus pneumoniae / Q000235:genetics