title: Streptococcus pneumoniae serotype-2 childhood meningitis in Bangladesh: a newly recognized pneumococcal infection threat.
abstract: BACKGROUND
  Streptococcus pneumoniae is a leading cause of meningitis in countries where pneumococcal conjugate vaccines (PCV) targeting commonly occurring serotypes are not routinely used. However, effectiveness of PCV would be jeopardized by emergence of invasive pneumococcal diseases (IPD) caused by serotypes which are not included in PCV. Systematic hospital based surveillance in Bangladesh was established and progressively improved to determine the pathogens causing childhood sepsis and meningitis. This also provided the foundation for determining the spectrum of serotypes causing IPD. This article reports an unprecedented upsurge of serotype 2, an uncommon pneumococcal serotype, without any known intervention.
  
  
  RESULTS
  Cases with suspected IPD had blood or cerebrospinal fluid (CSF) collected from the beginning of 2001 till 2009. Pneumococcal serotypes were determined by capsular swelling of isolates or PCR of culture-negative CSF specimens. Multicenter national surveillance, expanded from 2004, identified 45,437 patients with suspected bacteremia who were blood cultured and 10,618 suspected meningitis cases who had a lumber puncture. Pneumococcus accounted for 230 culture positive cases of meningitis in children <5 years. Serotype-2 was the leading cause of pneumococcal meningitis, accounting for 20.4% (45/221; 95% CI 15%-26%) of cases. Ninety eight percent (45/46) of these serotype-2 strains were isolated from meningitis cases, yielding the highest serotype-specific odds ratio for meningitis (29.6; 95% CI 3.4-256.3). The serotype-2 strains had three closely related pulsed field gel electrophoresis types.
  
  
  CONCLUSIONS
  S. pneumoniae serotype-2 was found to possess an unusually high potential for causing meningitis and was the leading serotype-specific cause of childhood meningitis in Bangladesh over the past decade. Persisting disease occurrence or progressive spread would represent a major potential infection threat since serotype-2 is not included in PCVs currently licensed or under development.
authors.affiliation: Department of Microbiology, Dhaka Shishu (Children) Hospital, Child Health Research Foundation, Dhaka, Bangladesh. samirk.sks@gmail.com
authors.forename: Samir K
authors.initials: SK
authors.lastname: Saha
authors.forename: Hassan M
authors.initials: HM
authors.lastname: Al Emran
authors.forename: Belal
authors.initials: B
authors.lastname: Hossain
authors.forename: Gary L
authors.initials: GL
authors.lastname: Darmstadt
authors.forename: Senjuti
authors.initials: S
authors.lastname: Saha
authors.forename: Maksuda
authors.initials: M
authors.lastname: Islam
authors.forename: Atique I
authors.initials: AI
authors.lastname: Chowdhury
authors.forename: Dona
authors.initials: D
authors.lastname: Foster
authors.forename: Aliya
authors.initials: A
authors.lastname: Naheed
authors.forename: Shams
authors.initials: S
authors.lastname: El Arifeen
authors.forename: Abdullah H
authors.initials: AH
authors.lastname: Baqui
authors.forename: Shamim A
authors.initials: SA
authors.lastname: Qazi
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Luby
authors.forename: Robert F
authors.initials: RF
authors.lastname: Breiman
authors.forename: Mathuram
authors.initials: M
authors.lastname: Santosham
authors.forename: Robert E
authors.initials: RE
authors.lastname: Black
authors.forename: Derrick W
authors.initials: DW
authors.lastname: Crook
mesh_terms: D017677:Age Distribution; D000942:Antigens, Bacterial / Q000134:cerebrospinal fluid; D001459:Bangladesh / Q000453:epidemiology; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005843:Geography; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008586:Meningitis, Pneumococcal / Q000134:cerebrospinal fluid / Q000453:epidemiology* / Q000382:microbiology; D016133:Polymerase Chain Reaction; D011159:Population Surveillance / Q000379:methods; D015995:Prevalence; D012703:Serotyping; D013045:Species Specificity; D013296:Streptococcus pneumoniae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D000942:Antigens, Bacterial; D004269:DNA, Bacterial