Emergence of Serotype IV Group B Streptococcus Adult Invasive Disease in Manitoba and Saskatchewan, Canada, Is Driven by Clonal Sequence Type 459 Strains

Abstract

Serotype IV group B Streptococcus (GBS) is emerging in Canada and the United States with rates as high as 5% of the total burden of adult invasive GBS disease. To understand this emergence, we studied the population structure and assessed the antimicrobial susceptibility of serotype IV isolates causing adult invasive infection in Manitoba and Saskatchewan, Canada, between 2010 and 2014. Whole-genome sequencing was used to determine multilocus sequence typing information and identify genes encoding antimicrobial resistance in 85 invasive serotype IV GBS strains. Antimicrobial susceptibility testing was performed by standard methods. Strain divergence was assessed using genome-wide single-nucleotide polymorphism analysis. Serotype IV strains were responsible for 16.9% of adult invasive GBS infections in Manitoba and Saskatchewan during the period. The majority of serotype IV isolates (89%) were clonally related, tetracycline-, erythromycin-, and clindamycin-resistant sequence type 459 (ST459) strains that possessed genes tetM and ermTR. Genome comparisons between ST459 and serotype V ST1 GBS identified several areas of recombination in an overall similar genomic background. Serotype IV ST459 GBS strains are expanding and causing a substantial percentage of adult invasive GBS disease. This emergence may be linked to the acquisition of resistance to tetracycline, macrolides, and lincosamides.

Serotype Distribution, Population Structure, and Antimicrobial Resistance of Group B Streptococcus Strains Recovered from Colonized Pregnant Women

“…Four of the serotype IV colonizing strains belonged to ST459, one belonged to the closely related ST196, and one belonged to ST452 (see Table S1). This ST distribution parallels the results for invasive serotype IV GBS reported in Toronto and elsewhere in Canada (29,30). To understand the genetic relationship between colonizing and invasive ST459 strains circulating in Canada and the United States, we sequenced the genomes of all four colonizing serotype IV ST459 strains in our collection.…”

“…The emergence of serotype IV GBS as an agent of invasive disease, particularly among adults, was first reported in the United States (27,46) and later in Canada (31,34). Frequencies of less than 1% were common in the 1990s (46) but have increased to 6 to 12% in populations studied between 2008 and 2015 (27,29,30,47). The emergence of serotype IV GBS among colonizing isolates has also been noticed in the United States (28) and Europe (48).…”

“…For example, earlier reports from Minnesota described the isolation of serotype IV GBS strains belonging to different STs among isolates of both colonizing and neonatal invasive GBS in the United States (27,28). We and others recently described an increase in the frequency of isolation of serotype IV strains among invasive GBS infections in Canada (29)(30)(31). In addition, as exemplified by polyvalent conjugate pneumococcal vaccination schemes (32), vaccinating with the GBS trivalent formulation may select for vaccine escape recombinants through capsular switching.…”

Prevalence of macrolide–lincosamide resistance and multidrug resistance phenotypes in streptococcal isolates causing infections in European hospitals: Evaluation of the in vitro activity of oritavancin and comparator agents

“…b-Haemolytic streptococcal (BHS) isolates are important human pathogens causing a variety of clinical infection syndromes [1][2][3]. Streptococcus pyogenes causes an estimated 700 million cases of mild non-invasive infection each year worldwide, of which approximately 650,000 progress to severe invasive (at a sterile site) infections with an associated mortality of ca.…”

Identification of Group B Streptococcus Capsule Type by Use of a Dual Phenotypic/Genotypic Assay

“…In North America and a number of European countries, five CPS types (Ia, Ib, II, III, and V) cause the bulk of invasive disease cases, with CPS III causing a higher rate of disease among neonates and CPS types Ia and V causing higher rates among adult patients (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). Interestingly, recent studies have noted the emergence and circulation of CPS IV, a previously uncommon serotype, as an important cause of both neonatal and adult infections (14,19,(24)(25)(26)(27)(28).…”