viernes, 2 de enero de 2015

Detection of co-colonization with Streptococcus pneumoniae by algor... - PubMed - NCBI

2014 Dec 15. pii: S0264-410X(14)01593-X. doi: 10.1016/j.vaccine.2014.11.040. [Epub ahead of print]

Detection of co-colonization with Streptococcus pneumoniae by algorithmic use of conventional and molecular methods.

Saha S1, Modak JK1, Naziat H1, Al-Emran HM1, Chowdury M1, Islam M1, Hossain B1, Darmstadt GL2, Whitney CG3, Saha SK4.

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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.