Genome Biol Evol. 2016 Mar 24. pii: evw066. [Epub ahead of print]

Comparative genomics of carriage and disease isolates of Streptococcus pneumoniae serotype 22F reveals lineage specific divergence and niche adaptation.

Cleary DW1, Devine VT2, Jefferies J1, Webb JS3, Bentley SD4, Gladstone RA4, Faust SN5, Clarke SC6.

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Streptococcus pneumoniaeis a major cause of meningitis, sepsis and pneumonia worldwide. Pneumococcal conjugate vaccines (PCV) have been part of the UK's childhood immunisation programme since 2006 and have significantly reduced the incidence of disease due to vaccine efficacy in reducing carriage in the population. Here we isolated two clones of 22F (an emerging serotype of clinical concern, multilocus sequence types (MLST) 433 and 698) and conducted comparative genomic analysis on four isolates, paired by ST with one of each pair being derived from carriage and the other disease (sepsis). The most compelling observation was of non-synonymous mutations inpgdA, encoding peptidoglycanN-acetylglucosamine deacetylase A, which were found in the carriage isolates of both ST433 and 698. Deacetylation of pneumococcal peptidoglycan is known to enable resistance to lysozyme upon invasion. Whilst no other clear genotypic signatures related to disease or carriage could be determined, additional intriguing comparisons between the two STs were possible. These include the presence of an intact prophage, in addition to numerous additional phage insertions, within the carriage isolate of ST433. Contrasting gene repertoires related to virulence and colonisation, including: bacteriocins, lantibiotics, and toxin-antitoxin systems, were also observed.

© The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.


Genome sequencing; Invasive pneumococcal disease (IPD); Streptococcus pneumoniae

PMID: 27016484 [PubMed - as supplied by publisher]