Population Structure and Antimicrobial Resistance of Invasive Serotype IV Group B Streptococcus, Toronto, Ontario, Canada
Emerging Infectious Diseases MAY 2015 V.21 N.4
Sarah Teatero, Allison McGeer, Aimin Li, Janice Gomes, Christine Seah, Walter Demczuk, Irene Martin, Jessica Wasserscheid, Ken Dewar, Roberto G. Melano, and Nahuel Fittipaldi
Public Health Ontario, Toronto, Ontario, Canada (S. Teatero, A. Li, J. Gomes, C. Seah, R.G. Melano, N. Fittipaldi); University of Toronto, Toronto (A. McGeer, R.G. Melano, N. Fittipaldi); Mount Sinai Hospital, Toronto (A. McGeer, R.G. Melano); Public Health Agency of Canada, Winnipeg, Manitoba, Canada (W. Demczuk, I. Martin); McGill University, Montreal, Quebec, Canada (J. Wasserscheid, K. Dewar); Genome Quebec Innovation Centre, Montreal (J. Wasserscheid, K. Dewar)
We recently showed that 37/600 (6.2%) invasive infections with group B Streptococcus (GBS) in Toronto, Ontario, Canada, were caused by serotype IV strains.
We report a relatively high level of genetic diversity in 37 invasive strains of this emerging GBS serotype. Multilocus sequence typing identified 6 sequence types (STs) that belonged to 3 clonal complexes.
Most isolates were ST-459 (19/37, 51%) and ST-452 (11/37, 30%), but we also identified ST-291, ST-3, ST-196, and a novel ST-682.
We detected further diversity by performing whole-genome single-nucleotide polymorphism analysis and found evidence of recombination events contributing to variation in some serotype IV GBS strains.
We also evaluated antimicrobial drug resistance and found that ST-459 strains were resistant to clindamycin and erythromycin, whereas strains of other STs were, for the most part, susceptible to these antimicrobial drugs.