Streptococcus bovis-bacteremia: subspecies distribution and association with colorectal cancer: a retrospective cohort study

Abstract

This study aimed to describe the incidence of Streptococcus bovis/Streptococcus equinus complex (SBSEC) bacteremia, distribution of the SBSEC subspecies, and their respective association with colorectal cancer (CRC). A population-based retrospective cohort study of all episodes of SBSEC-bacteremia from 2003 to 2018 in Skåne Region, Sweden. Subspecies was determined by whole-genome sequencing. Medical charts were reviewed. The association between subspecies and CRC were analysed using logistic regression. In total 266 episodes of SBSEC-bacteremia were identified and the average annual incidence was 2.0 per 100 000 inhabitants. Of the 236 isolates available for typing, the most common subspecies was S. gallolyticus subsp. pasteurianus 88/236 (37%) followed by S. gallolyticus subsp. gallolyticus 58/236 (25%). In order to determine the risk of cancer following bacteremia, an incidence cohort of 174 episodes without a prior diagnosis of CRC or metastasised cancer was followed for 560 person-years. CRC was found in 13/174 (7%), of which 9 (69%) had S. gallolyticus subsp. gallolyticus-bacteremia. In contrast to other European studies, S. gallolyticus subsp. pasteurianus was the most common cause of SBSEC-bacteremia. CRC diagnosis after bacteremia was strongly associated with S. gallolyticus subsp. gallolyticus-bacteremia. Identification of SBSEC subspecies can guide clinical decision-making regarding CRC work-up following bacteremia.

Platelet Activation and Aggregation Induced by Streptococcus bovis / Streptococcus equinus Complex

“…The isolates tested belonged to four different species or subspecies of the SBSEC (see Table 1 ). The three additional (sub)species in the complex are rarely involved in human infections, and therefore, are less relevant for this study ( 29 ). No clear difference could be seen between the different species regarding aggregation, with at least two isolates of each tested subspecies inducing aggregation in one or more donors.…”

“…Twenty-six SBSEC blood isolates from patients with bacteremia were collected from the diagnostic laboratory of Clinical Microbiology, Region Skåne, Lund, Sweden. Subspecies were determined through whole-genome sequencing as previously described ( 29 ). S. pyogenes strain AP1 was used as a comparative control strain ( 22 ).…”