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J Antimicrob Chemother. 2018 Jul 1;73(suppl_7):vii20-vii31. doi: 10.1093/jac/dky157.

Molecular characterization of predominant Streptococcus pneumoniae serotypes causing invasive infections in Canada: the SAVE study, 2011-15.

Author information

1
Department of Medical Microbiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada.
2
Clinical Microbiology - Health Sciences Centre, Diagnostic Services Manitoba, MS673-820 Sherbrook Street, Winnipeg, Manitoba R3A 1R9, Canada.
3
National Microbiology Laboratory - Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba R3E 3R2, Canada.
4
Cadham Provincial Laboratory, 750 William Avenue, Winnipeg, Manitoba R3E 3J7, Canada.
5
Public Health Ontario, 661 University Avenue, Toronto, Ontario M5G 1M1, Canada.
6
Laboratoire de santé publique du Québec, 20045 Ch Ste-Marie, Ste-Anne-de-Bellevue, Québec H9X 3R5, Canada.
7
Saskatchewan Disease Control Laboratory, 5 Research Drive, Regina, Saskatchewan S4S 0A4, Canada.
8
Newfoundland and Labrador Public Health Laboratory, Dr. Leonard A. Miller Centre - Suite 1, 100 Forest Road, St John's, Newfoundland and Labrador A1A 1E3, Canada.
9
Queen Elizabeth II Health Science Centre, 5805 South Street, Halifax, Nova Scotia B3H 1V8, Canada.
10
New Brunswick Department of Health, 520 King Street, Fredericton, New Brunswick E3B 5G8, Canada.
11
Health PEI, 16 Garfield Street, Charlottetown, Prince Edward Island C1A 7N8, Canada.

Abstract

Objectives:

This study characterized the 11 most predominant serotypes of invasive Streptococcus pneumoniae infections collected by the annual SAVE study in Canada, between 2011 and 2015.

Methods:

A subset of the 11 most predominant serotypes (7F, 19A, 22F, 3, 12F, 11A, 9N, 8, 33F, 15A and 6C) collected by the SAVE study was analysed using PFGE and MLST, as well as PCR to identify pilus-encoding genes. WGS analyses were performed on a subset of the above isolates plus a random selection of background strains.

Results:

Of the predominant serotypes analysed, 7F, 33F and 19A were obtained more commonly from children <6 years of age, whereas 15A, 6C, 22F and 11A were more common in adults >65 years of age. Pneumococcal pilus PI-1 was identified in antimicrobial-susceptible serotype 15A (61/212) and <10% of 6C isolates (16/188). PI-2 was found in serotype 7F (683/701) and two-thirds of 11A isolates (162/241). Only serotype 19A-ST320 possessed both pili. Molecular and phylogenetic analyses identified serotypes 19A, 15A, 6C, 9N and 33F as highly diverse, whereas 7F, 22F and 11A demonstrated clonality. Antimicrobial resistance determinants were common within diverse serotypes, and usually similar within a clonal complex.

Conclusions:

Despite successful use of conjugate vaccines, S. pneumoniae remains a highly diverse organism in Canada. Several predominant serotypes, both antimicrobial susceptible and MDR, have demonstrated rapid clonal expansion or an increase in diversity. As S. pneumoniae continues to evolve in Canada, WGS will be a necessary component in the ongoing surveillance of antimicrobial-resistant and expanding clones.

PMID:
29982573
DOI:
10.1093/jac/dky157

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