An unusual Streptococcus from human urine, Streptococcus urinalis sp. nov

Researchers identified a novel Streptococcus species isolated from the urine of a 55-year-old female patient with cystitis. Using combined biochemical, molecular chemical, and genetic approaches, they characterized the unknown Gram-positive, catalase-negative coccus. The organism was non-haemolytic, bacitracin-resistant, and lacked Lancefield group antigens. Comparative 16S rRNA gene sequencing revealed it belongs to the 'pyogenic subgroup' of Streptococcus, with closest phylogenetic relationships to Streptococcus pyogenes and Streptococcus canis at approximately 2.5% sequence divergence. However, whole-cell protein electrophoresis and extensive biochemical testing clearly distinguished it as a separate species. The unknown isolate differed notably from related species in being non-haemolytic and lacking group A or G antigens. Based on phenotypic and phylogenetic evidence, the authors propose this bacterium represents a new species, designated Streptococcus urinalis sp. nov., with type strain CCUG 41590T. The formal description is supported by its recovery from clinical specimens and distinct taxonomic characteristics, though currently only a single strain is known.

Key findings

• A new Streptococcus species, S. urinalis, was isolated from human urine and formally described based on combined phenotypic and molecular genetic analysis
• 16S rRNA sequencing showed S. urinalis clusters within the 'pyogenic subgroup' with approximately 2.5% sequence divergence from closest relatives S. pyogenes and S. canis, supporting its status as a distinct species
• The organism is non-haemolytic, bacitracin-resistant, and lacks Lancefield group antigens, distinguishing it from closely related pyogenic streptococci
• Whole-cell protein electrophoresis confirmed S. urinalis as phylogenetically and phenotypically distinct from known streptococcal species