International genomic definition of pneumococcal lineages, to contextualise disease, antibiotic resistance and vaccine impact.

Abstract

BACKGROUND:

Pneumococcal conjugate vaccines have reduced the incidence of invasive pneumococcal disease, caused by vaccine serotypes, but non-vaccine-serotypes remain a concern. We used whole genome sequencing to study pneumococcal serotype, antibiotic resistance and invasiveness, in the context of genetic background.

METHODS:

Our dataset of 13,454 genomes, combined with four published genomic datasets, represented Africa (40%), Asia (25%), Europe (19%), North America (12%), and South America (5%). These 20,027 pneumococcal genomes were clustered into lineages using PopPUNK, and named Global Pneumococcal Sequence Clusters (GPSCs). From our dataset, we additionally derived serotype and sequence type, and predicted antibiotic sensitivity. We then measured invasiveness using odds ratios that relating prevalence in invasive pneumococcal disease to carriage.

FINDINGS:

The combined collections (n = 20,027) were clustered into 621 GPSCs. Thirty-five GPSCs observed in our dataset were represented by >100 isolates, and subsequently classed as dominant-GPSCs. In 22/35 (63%) of dominant-GPSCs both non-vaccine serotypes and vaccine serotypes were observed in the years up until, and including, the first year of pneumococcal conjugate vaccine introduction. Penicillin and multidrug resistance were higher (p < .05) in a subset dominant-GPSCs (14/35, 9/35 respectively), and resistance to an increasing number of antibiotic classes was associated with increased recombination (R2 = 0.27 p < .0001). In 28/35 dominant-GPSCs, the country of isolation was a significant predictor (p < .05) of its antibiogram (mean misclassification error 0.28, SD ± 0.13). We detected increased invasiveness of six genetic backgrounds, when compared to other genetic backgrounds expressing the same serotype. Up to 1.6-fold changes in invasiveness odds ratio were observed.

INTERPRETATION:

We define GPSCs that can be assigned to any pneumococcal genomic dataset, to aid international comparisons. Existing non-vaccine-serotypes in most GPSCs preclude the removal of these lineages by pneumococcal conjugate vaccines; leaving potential for serotype replacement. A subset of GPSCs have increased resistance, and/or serotype-independent invasiveness.

• Authors: Rebecca A Gladstone, Stephanie W Lo, John A Lees, Nicholas J Croucher, Andries J van Tonder, Jukka Corander, Andrew J Page, Pekka Marttinen, Leon J Bentley, Theresa J Ochoa, Pak Leung Ho, Mignon du Plessis, Jennifer E Cornick, Brenda Kwambana-Adams, Rachel Benisty, Susan A Nzenze, Shabir A Madhi, Paulina A Hawkins, Dean B Everett, Martin Antonio, Ron Dagan, Keith P Klugman, Anne von Gottberg, Lesley McGee, Robert F Breiman, Stephen D Bentley, Global Pneumococcal Sequencing Consortium
• Journal: EBioMedicine (EBioMedicine) Vol. 43 Pg. 338-346 (May 2019) ISSN: 2352-3964 [Electronic] Netherlands
• PMID: 31003929 (Publication Type: Journal Article)
• Copyright: Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.

Chemical References

• Anti-Bacterial Agents
• Pneumococcal Vaccines

Topics

• Anti-Bacterial Agents (pharmacology, therapeutic use)
• Biodiversity
• Drug Resistance, Bacterial
• Evolution, Molecular
• Female
• Genome, Bacterial
• Genomics (methods)
• Genotype
• Global Health
• Humans
• Male
• Pneumococcal Infections (drug therapy, epidemiology, microbiology, prevention & control)
• Pneumococcal Vaccines
• Polymorphism, Single Nucleotide
• Serogroup
• Streptococcus pneumoniae (classification, drug effects, genetics, immunology)