Streptococcus equinus

Abstract: ‘Streptococcus bovis/Streptococcus equinus’ is a large bacterial complex including different species frequently isolated from infections of humans (Streptococcus gallolyticus, Streptococcus infantarius) or animals (S. bovis, S. equinus, Streptococcus alactolyticus). The separation of S. bovis into three different biotypes has been partially correlated with genetic differentiation. In addition, recent advances in bacterial phylogeny have led to the inclusion of Streptococcus macedonicus and Streptococcus waius in this complex. The aim of this study was to improve physiological differentiation between species related to the complex and to clarify their respective phylogenetic positions. In this study, physiological, genetic and phylogenetic analyses of a set of 88 streptococcal strains were performed. The diversity of strains of S. bovis biotype II was analysed, and it was confirmed that they belong to different species, either S. equinus or S. infantarius. It was demonstrated that S. gallolyticus, S. bovis biotype II.2, S. macedonicus and S. waius form a single DNA cluster separated into three different subspecies. They are delineated by different biochemical traits, limited DNA–DNA relatedness and noticeable divergence in 16S rDNA sequences. According to the current definition of species, the names S. gallolyticus subsp. gallolyticus subsp. nov., S. gallolyticus subsp. pasteurianus subsp. nov. and S. gallolyticus subsp. macedonicus subsp. nov. are proposed for these three subspecies.

Abstract: The speciation of 262 strains of group D streptococci isolated from human sources is described. One hundred forty-two isolates from blood cultures were included; 96 of these were submitted as isolates from clinical cases of subacute bacterial endocarditis. The results show that 98 Streptococcus faecalis, 29 S. faecalis var. zymogenes, 44 S. faecalis var. liquefaciens, 27 S. faecium, 13 S. durans, 44 S. bovis, and 7 unspeciated S. bovis-like group D isolates were identified. No S. faecium var. casseliflavus, S. equinus, or S. avium (group Q streptococci) were identified among the human isolates. The speciation procedures and techniques are detailed. The procedures and limitations of the tests used are discussed. Ninety-eight percent of the 262 strains were speciated by a spectrum of tests that allowed us to recognize atypical as well as typical strains within species.

Abstract: The comparative survival of various fecal indicator bacteria and enteric pathogens was studied in a stable well water supply by using membrane chambers There was more variation in the 29 coliform cultures and they died more rapidly, as a group, than the 20 enterococcus cultures that were examined The comparative survival of the organisms tested follows: Aeromonas sp > the shigellae (Shigella flexneri, S sonnei, and S dysenteriae) > fecal streptococci > coliforms = some salmonellae (Salmonella enteritidis ser paratyphi A and D, S enteritidis ser typhimurium) > Streptococcus equinus > Vibrio cholerae > Salmonella typhi > Streptococcus bovis > Salmonella enteritidis ser paratyphi B S bovis had a more rapid die-off than did S equinus, but both had significantly shorter half-lives than the other streptococci The natural populations of indicator bacteria from human and elk fecal material declined similarly to the pure cultures tested, whereas the die-off of fecal streptococci exceeded the coliforms from bovine fecal material

Abstract: The taxonomic dissection of the Streptococcus bovis-Streptococcus equinus group was carried out upon obtaining sequences for the manganese-dependent superoxide dismutase gene (sodA) of the type strains of S. bovis, Streptococcus caprinus, S. equinus, Streptococcus gallolyticus, Streptococcus infantarius, Streptococcus macedonicus and Streptococcus waius. The sodA sequences of 29 streptococcal strains of animal and human origin that were related to S. bovis were also sequenced. A phylogenetic analysis of the sodA sequences revealed that the S. bovis-S. equinus group comprises five different clusters that correspond to five distinct species. The type strains of S. bovis and S. equinus were associated in the same cluster, corresponding to the species S. equinus. The type strains of S. caprinus, S. gallolyticus, S. macedonicus and S. waius were associated in the same cluster, which defined a single species containing S. gallolyticus and its junior synonym S. caprinus, and S. macedonicus and its junior synonym S. waius. The two subspecies thought to constitute the species S. infantarius, namely S. infantarius subsp. infantarius and 'S. infantarius subsp. coli', were located in two distinct clusters. One of these clusters defined the species S. infantarius and included the type strain of S. infantarius subsp. infantarius. The other cluster defined 'S. infantarius subsp. coli', leading to the proposal of its reclassification as the novel species Streptococcus lutetiensis (NEM 782T = CIP 106849T). The remaining cluster comprised all of the strains previously identified as belonging to S. bovis biotype 11.2, leading to the proposal to reassign these strains to the novel species Streptococcus pasteurianus (NEM 1202T = CIP 107122T). The results of the phylogenetic analysis were confirmed by DNA-DNA hybridization experiments, thus demonstrating that sequence databases of defined DNA targets, such as sodA, may constitute a valuable alternative approach for modern bacterial systematics.