Streptococcus bovis-Streptococcus equinus complex and gastrointestinal cancer: Epidemiology, etiology and diagnostics

An association exists between Streptococcus bovis-Streptococcus equinus complex (SBSEC) bacteraemia and colorectal cancer (CRC).SBSEC comprises seven subspecies, but it is unclear if all are linked to CRC, and potential associations with other gastrointestinal cancers have been suggested.The timing of CRC diagnosis relative to bacteraemia is understudied.There is limited knowledge on the proportions of infective endocarditis (IE) diagnosed in bacteraemia for each SBSEC subspecies.The current routine bacterial identification method, Matrix-assisted desorption/ionisation-Time of flight mass spectrometry (MALDI-TOF MS), cannot discriminate between the different (sub-)species using available libraries.Paper I used 1:10 matched population controls and was conducted nationally in Sweden 2010-2019 using registry data and examined when in time CRC is diagnosed following SBSEC-bacteraemia and the frequency of other gastrointestinal cancers.Most CRCs were diagnosed within the first year, although CRC diagnoses were elevated through the remainder of follow-up.There were no differences in the frequency of other gastrointestinal cancers following bacteraemia.