Bloodstream infection due to β-hemolytic streptococci: a population-based comparative analysis.

Purpose: Although the burden of illness due to Streptococcus pyogenes is widely recognized, other β-hemolytic streptococci are also important causes of invasive infections. The objective of this study was to compare the population-based epidemiology of groups A, B, and C/G β-hemolytic streptococcal bloodstream infection (BSI).

Methods: Population-based surveillance was conducted in the western interior of British Columbia, Canada, 2011-2018.

Results: A total of 210 episodes were identified for an incidence of 14.4 per 100,000; the incidences of groups A, B and C/G streptococcal BSI were 4.2, 4.7, and 5.5 per 100,000, respectively. There was an increasing annual incidence of β-hemolytic streptococcal BSI from 2011 through to a peak incidence in 2016 that decreased thereafter. Fifty-two percent (110) of BSIs were community associated, 43% (91) were healthcare associated, and 4% (9) were hospital onset. Patients with group A were younger, more likely to be female, and have fewer co-morbidities than patients with groups B and C/G streptococcal BSI. The most common focus of infection was soft tissue (109/52%), followed by primary (33; 16%), and bone and joint (20; 10%) and these varied by streptococcal species (p < 0.001). The 30-day all-cause case fatality rate was 11% (24/210) and did not significantly vary by group (p = 0.7).

Conclusion: Although the determinants vary, the overall burden of disease related to BSI is similar amongst groups A, B and C/G β-hemolytic streptococci.