Epidemiologic features of invasive group A Streptococcus infection in a rural hospital: 6-year retrospective report and literature review

Abstract

Introduction: High rates of invasive group A Streptococcus disease were suspected by clinicians in northwestern Ontario. Patients with sepsis were being encountered with bacteremia positive for group A Streptococcus. This study was designed to assess the incidence of invasive group A Streptococcus infection in the region and provide best-practice treatment information.

Methods: We performed a retrospective chart review at the Sioux Lookout Meno Ya Win Health Centre (SLMHC) from 2009 to 2014 to examine rates of infection due to invasive group A Streptococcus and outcomes. All blood cultures from 2015 were also examined to calculate the relative rates of distinct pathogens responsible for cases of bacteremia. A literature review on this topic was performed, with attention to rural incidence where available and clinical practice guidelines.

Results: Invasive group A Streptococcus disease was diagnosed in 65 patients during the study period. Most (37 [57%]) had bacteremia without a clinical focus. Type 2 diabetes mellitus was a comorbid condition in 27 (42%) and skin conditions in 30 (46%). The case fatality rate was 4.6%. In 2015, group A Streptococcus accounted for 8% of all positive blood cultures from in- and outpatients in the catchment area. The calculated annual incidence rate of invasive group A Streptococcus infection was 37.2 cases per 100 000 population.

Conclusion: Rural physicians may encounter group A Streptococcus bacteremia in their practice. The death rate associated with these infections can be as high as 20%, and patients require urgent treatment, typically with intravenous penicillin and clindamycin therapy. The rate of invasive group A Streptococcus infection in the predominantly First Nations population served by the SLMHC exceeded the Canadian rate eightfold and is comparable to rates observed in low-income countries and among Indigenous populations in Australia. This disparity may result from inadequate housing, overcrowding or limited access to clean water.