title: Detection of co-colonization with Streptococcus pneumoniae by algorithmic use of conventional and molecular methods.
abstract: Detection of pneumococcal carriage by multiple co-colonizing serotypes is important in assessing the benefits of pneumococcal conjugate vaccine (PCV). Various methods differing in sensitivity, cost and technical complexity have been employed to detect multiple serotypes of pneumococcus in respiratory specimens. We have developed an algorithmic method to detect all known serotypes that preserves the relative abundance of specific serotypes by using Quellung-guided molecular techniques. The method involves culturing respiratory swabs followed by serotyping of 100 colonies by either capsular (10 colonies) or PCR (90 colonies) reactions on 96-well plates. The method was evaluated using 102 nasal swabs from children carrying pneumococcus. Multiple serotypes were detected in 22% of carriers, compared to 3% by World Health Organization (WHO)-recommended morphology-based selection of 1 to 3 colonies. Our method, with a processing cost of $87, could detect subdominant strains making up as low as 1% of the population. The method is affordable, practical, and capable of detecting all known serotypes without false positive reactions or change in the native distribution of multiple serotypes.
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Bangladesh Institute of Child Health, Dhaka, Bangladesh.
authors.forename: Sudipta
authors.initials: S
authors.lastname: Saha
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Bangladesh Institute of Child Health, Dhaka, Bangladesh.
authors.forename: Joyanta K
authors.initials: JK
authors.lastname: Modak
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Bangladesh Institute of Child Health, Dhaka, Bangladesh.
authors.forename: Hakka
authors.initials: H
authors.lastname: Naziat
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Bangladesh Institute of Child Health, Dhaka, Bangladesh.
authors.forename: Hassan M
authors.initials: HM
authors.lastname: Al-Emran
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Bangladesh Institute of Child Health, Dhaka, Bangladesh.
authors.forename: Mrittika
authors.initials: M
authors.lastname: Chowdury
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Bangladesh Institute of Child Health, Dhaka, Bangladesh.
authors.forename: Maksuda
authors.initials: M
authors.lastname: Islam
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Bangladesh Institute of Child Health, Dhaka, Bangladesh.
authors.forename: Belal
authors.initials: B
authors.lastname: Hossain
authors.affiliation: Global Development Division, Bill and Melinda Gates Foundation, Seattle, WA, USA.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Darmstadt
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Cynthia G
authors.initials: CG
authors.lastname: Whitney
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Bangladesh Institute of Child Health, Dhaka, Bangladesh. Electronic address: Samir@chrfbd.org.
authors.forename: Samir K
authors.initials: SK
authors.lastname: Saha
mesh_terms: D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology*; D002675:Child, Preschool; D060085:Coinfection / Q000453:epidemiology* / Q000382:microbiology*; D003365:Costs and Cost Analysis; D005260:Female; D060005:Genotyping Techniques / Q000191:economics / Q000379:methods; D006801:Humans; D007223:Infant; D008297:Male; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D065288:Serogroup; D012703:Serotyping / Q000191:economics / Q000379:methods; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification*
keywords: Carriage; Co-colonization; Pneumococcus; Quantitative detection