Characterization of MDR and XDR Streptococcus pneumoniae in Canada, 2007-13.
OBJECTIVE
The goal of this study was to characterize Streptococcus pneumoniae demonstrating MDR (resistant to three or more antimicrobial classes) or XDR (resistant to five or more classes) phenotypes, collected from Canada during the CANWARD 2007-13 study.


METHODS
From 2007 to 2013 inclusive, S. pneumoniae isolates were collected as a part of the CANWARD surveillance study. MDR and XDR isolates were subjected to PFGE, MLST, molecular detection of pneumococcal pili and macrolide resistance determinants mef(A/E) and erm(B), sequencing of PBPs 1A, 2B and 2X and comparison with Pneumococcal Molecular Epidemiology Network (PMEN) clones.


RESULTS
Of 2129 S. pneumoniae isolates collected during the CANWARD 2007-13 study, 61 (2.9%) were found to be MDR. Of these MDR isolates, 43 (70.5%) were XDR. The most common serotypes for both MDR and XDR S. pneumoniae were 19A and 19F. Twenty-nine of 61 isolates (48%) demonstrated resistance to clarithromycin, clindamycin, doxycycline, penicillin and trimethoprim/sulfamethoxazole. All isolates possessed at least one macrolide resistance determinant and mutations in PBPs 1A, 2B and 2X. The most common clone was piliated, XDR ST320, an internationally circulating double-locus variant of Taiwan(19F)-14 (ST236).


CONCLUSIONS
Though the rate of MDR S. pneumoniae has remained relatively stable since 2007, XDR strains have emerged in Canada. These strains are virulent, possess resistance determinants and are related to international clones.
Department of Medical Microbiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada umgoldea@myumanitoba.ca.
Alyssa R
AR
Golden
Department of Medical Microbiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada.
Margot
M
Rosenthal
Department of Medical Microbiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada.
Ben
B
Fultz
Clinical Microbiology - Health Sciences Centre, Diagnostic Services Manitoba, MS673-820 Sherbrook Street, Winnipeg, Manitoba R3A 1R9, Canada.
Kimberly A
KA
Nichol
Department of Medical Microbiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada Clinical Microbiology - Health Sciences Centre, Diagnostic Services Manitoba, MS673-820 Sherbrook Street, Winnipeg, Manitoba R3A 1R9, Canada.
Heather J
HJ
Adam
Department of Medical Microbiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada National Microbiology Laboratory-Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba R3E 3R2, Canada.
Matthew W
MW
Gilmour
Department of Medical Microbiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada.
Melanie R
MR
Baxter
Department of Medical Microbiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada Clinical Microbiology - Health Sciences Centre, Diagnostic Services Manitoba, MS673-820 Sherbrook Street, Winnipeg, Manitoba R3A 1R9, Canada.
Daryl J
DJ
Hoban
Department of Medical Microbiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada Clinical Microbiology - Health Sciences Centre, Diagnostic Services Manitoba, MS673-820 Sherbrook Street, Winnipeg, Manitoba R3A 1R9, Canada.
James A
JA
Karlowsky
Department of Medical Microbiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada.
George G
GG
Zhanel
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002170:Canada / Q000453:epidemiology; D024901:Drug Resistance, Multiple, Bacterial; D062665:Epidemiological Monitoring; D005260:Female; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D058889:Molecular Typing; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D055815:Young Adult
D000900:Anti-Bacterial Agents
S. pneumoniae; extensively drug resistant; molecular characterization; multidrug resistant; resistance mechanisms