Streptococcus anginosus group bloodstream infections in the western interior of British Columbia, Canada

Background: The epidemiology of Streptococcus anginosus group (SaG) bloodstream infections (BSI) has not been well defined in non-selected populations. The objective of this study was to determine the incidence, risk factors and outcome associated with SaG BSI. Methods: Population-based surveillance was conducted in the western interior region of British Columbia, Canada between 1 April 2010 and 31 March 2017. Results: Forty-six episodes were identified for an overall annual incidence of 3.7 per 100,000 population. The incidence increased with older age and males were at significantly higher risk (5.2 vs. 2.1 per 100,000; incidence rate ratio, 2.5; 95% confidence interval, 1.3-5.1; p = .004). Nearly one-half (22; 48%) of patients had no chronic co-morbid illness, whereas 17 (40%) had 1-2, six (13%) had 3-4 and one (2%) had 5 Charlson scores with diabetes and cancer being the most common. Predisposing factors for development of SaG BSI were identified in 30 (65%) cases. The gastro-intestinal tract was the most common focus of infection (13; 28%) followed by cardiovascular and skin/soft tissue (six cases each; 13%) and in seven (15%) cases no focus was identified. Drainage procedures were required in 21 (46%) patients of whom seven (15%) patients had percutaneous drains and 14 (30%) required surgical operations. Forty-one (89%) patients were admitted to hospital for a median hospital length stay of 11 (interquartile range, 7-18) days. The in-hospital and 30-day all cause case-fatality rates were 3/41 (7%) and 4/46 (9%), respectively. Conclusion: SaG BSI is an important cause of morbidity and mortality.