Changing trends in β-hemolytic streptococcal bacteremia in Manitoba, Canada: 2007–2012

Abstract

Objectives: European surveillance studies have reported an increasing incidence of β-hemolytic group G streptococcal bacteremia, but no studies have evaluated trends in β-hemolytic streptococcal bacteremia in North America. Methods: We reviewed bacteremic episodes and positive throat swab cultures from two tertiary care centers in Manitoba, Canada, from January 2007 to December 2012. Results: During the study period, 19 864 bacteremic episodes, and 9948 positive throat swabs were identified. There were 1025 (5.16%) bacteremic episodes attributable to β-hemolytic streptococci: 425 (2.03%), 339 (1.71%), 62 (0.31%), and 199 (0.95%) to β-hemolytic groups A, B, C, and G streptococci, respectively. From 2007 to 2012, there were significant increases in the proportion of bacteremia attributable to β-hemolytic streptococci in general (6.32% vs. 4.02%; p < 0.0001; linear trend test, p < 0.0001), and to groups G (1.49% vs. 0.43%; p < 0.0001; linear trend test, p < 0.0001) and C (0.58% vs. 0.13%; p = 0.0068; linear trend test, p = 0.0105) β-hemolytic streptococci in particular. Bacteremia attributable to groups A and B β-hemolytic streptococci and Streptococcus pneumoniae were unchanged. There were no changes in the distribution of β-hemolytic streptococcal groups among throat swabs. Conclusions: Bacteremia attributable to β-hemolytic groups G and C streptococci increased in Manitoba, Canada. Further study of the factors underlying these changes is required.

Keywords

• β-Hemolytic streptococci
• Group G streptococci
• Group C streptococci
• Bacteremia
• Invasive streptococcal disease