Analysis of bacteraemia caused by group C and G Streptococcus (Streptococcus dysgalactiae subsp. equisimilis) in Western Sydney over a 6-year period (2015-2020)

Abstract

Purpose: Streptococcus dysgalactiae subsp. equisimilis (SDSE) has increasingly been recognised as a significant pathogen that causes a myriad of infections, ranging from cellulitis to invasive infections, including bacteraemia and even toxic shock syndrome. The aim of this study was to examine the epidemiology and disease manifestations of bacteraemia caused by SDSE.

Methods: We retrospectively reviewed cases of SDSE bacteraemia in adults aged ≥ 18 years admitted to four public hospitals in Western Sydney, Australia, between January 2015 and December 2020. We reviewed demographics, comorbidities, disease manifestations, management, and outcomes.

Results: There were 108 patients with SDSE bacteraemia over a six-year period. The median age of individuals with SDSE bacteraemia was 70 years (interquartile range, IQR, 58-85 years). Cardiovascular disease (46%), chronic skin conditions (44%) and diabetes (37%) were the most common comorbidities. Ten patients (9%) with SDSE bacteraemia had healthcare-acquired infections. Skin and skin structure infections (SSTIs) were the most common presentations (59%), while bone and joint infections (BJIs) represented 13% of the cases. Twenty patients (19%) had septic shock on presentation. Fifteen patients (14%) were prescribed clindamycin, while one patient received intravenous immunoglobulin (IVIg). Infective endocarditis (IE) was present in 3% of patients; however, only 44% of the total patients had an echocardiogram. The 30-day mortality rate was 13%, but it was greater in those aged > 75 years (21%). The average length of hospital stay for patients who survived was 15 days, and the average duration of intravenous therapy was 12 days.

Conclusion: SDSE bacteraemia is typically a community-onset infection with a fifth of patients in our cohort presenting with septic shock. Though complications such as BJI (13%) and IE (3%) are infrequent, 30-day mortality is high at 21% in those aged > 75 years.

Keywords: Streptococcus dysgalactiae subsp. equisimilis (SDSE); Epidemiology and clinical features; Group C and G Streptococcus (GCGS).