Streptococcus bovis new taxonomy: does subspecies distinction matter?

Abstract

Bacteremia with Streptococcus bovis/equinus complex strains is associated with hepatobiliary disease, colorectal lesions (CL), and infective endocarditis (IE). This study addressed the clinical significance of subspecies distinction of previously designated S. bovis blood culture isolates according to the updated nomenclature. During 2002-2013, all blood culture isolates previously designated as S. bovis were recultured and identified using 16S rRNA gene sequencing and MALDI-TOF (Bruker BioTyper and Vitek MS, bioMérieux). Clinical data of patients aged ≥18 years were reviewed. A review of four recent case series was performed as well. Forty blood isolates were identified using 16S rRNA sequencing. Twenty-six bacteremic patients had S. gallolyticus ssp. pasteurianus, six had S. gallolyticus ssp. gallolyticus, two had S. gallolyticus ssp. macedonicus, and six had S. infantarius bacteremia. Species diagnosis using Vitek and bioMérieux MALDI-TOF technology was applicable in 37 and 36 samples, respectively, and was successful in all samples (100 %). Subspecies identification was confirmed in 30 (83 %) samples (as compared with 16S rRNA sequencing detection). IE was diagnosed in 22 (59 %) patients and CL in 8 (20 %) patients. Both complications were associated with all subspecies. Combining our results with those of four recent series resulted in, overall, 320 bacteremic cases, of which 88 (28 %) had CL and 66 (21 %) had IE. All 'bovis/equinus' complex subspecies were associated with CL or IE. From a clinical point of view, species diagnosis using MALDI-TOF MS should suffice to warrant consideration of transesophageal echocardiography and colonoscopy.

Investigating the association between African spontaneously fermented dairy products, faecal carriage of Streptococcus infantarius subsp. infantarius and colorectal adenocarcinoma in Kenya

“…In this study, Sii was elevated among persons with CRC when compared to persons with normal colon (21.6%:8.4%) showed similar associations for Sii to CRC as to those of other SBSEC members ( Ben-Chetrit et al, 2017 ). The implied health risk of this Sii carriage in relation to CRC will require further investigations to elucidate causality of SBSEC and Sii in CRC as well as functional and genomic comparisons between the different Sii lineages.…”

“…The implied health risk of this Sii carriage in relation to CRC will require further investigations to elucidate causality of SBSEC and Sii in CRC as well as functional and genomic comparisons between the different Sii lineages. So far, little evidence on Sii -related diseases is available as mostly S. lutetiensis was detected or if S. infantarius -specific disease associations were reported then without differentiation between Sii and S. lutetiensis ( Ben-Chetrit et al, 2017 , Corredoira et al, 2013 ). Previous studies implicating SBSEC or S. infantarius in human infections might therefore require additional follow up work to elucidate the epidemiologic and functional data under the more discriminative current SBSEC taxonomy ( Ben-Chetrit et al, 2017 , Jans et al, 2016 , Jans et al, 2015 ).…”

“…CRC is associated with a number of environmental factors including: age above 50 years, smoking, drinking alcohol, obesity, consumption of saturated fats and red meat ( Joint WHO/FAO expert consultation group, 2003 ). Microorganisms such as members of the Streptococcus bovis/Streptococcus equinus complex (SBSEC) have also been associated with CRC ( Ben-Chetrit et al, 2017 , Boleij and Tjalsma, 2013 , Corredoira et al, 2015 ). Despite this association, some SBSEC members are also given commensal status in the gastrointestinal tract of humans and animals, while recent studies have even shown that traditional fermented dairy products (tFDP) in Africa are predominated by Streptococcus infantarius subsp.…”

“…gallolyticus ( Sgg ) formerly classified as S. bovis biotype I and Streptococcus gallolyticus subsp . pasteurianus ( Sgp ), formerly biotype II.2 ( Ben-Chetrit et al, 2017 , Jans et al, 2015 ). However, these advances in taxonomic differentiation among the SBSEC opened questions on disease associations of the S. infantarius branch (biotype II.1) including Sii and Streptococcus lutetiensis (intermediately named Streptococcus infantarius subsp.…”

“…coli ). Disease association with infective endocarditis and other clinical syndromes was partially clarified for S. lutetiensis but not for Sii as accurate epidemiological data on Sii is scarce ( Ben-Chetrit et al, 2017 , Jans et al, 2015 , Romero et al, 2011 ). In parallel to taxonomic advances, some Sii strains have been reclassified as Streptococcus equinus while others implicated as human or livestock pathogens were confirmed to be Sii suggesting the need to investigate the role of Sii with respect to public health ( Jans et al, 2016 ).…”