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Inducing Meningococcal Meningitis Serogroup C in Mice via Intracisternal Delivery
Published on: November 5, 2019
Streptococcus azizii sp. nov., isolated from naïve weanling mice
Patricia Lynn Shewmaker1, Anne M Whitney1, Christopher A Gulvik1
1Centers for Disease Control and Prevention, Atlanta, Georgia 30329, USA.
Abstract:
Three isolates of a previously reported novel catalase-negative, Gram-stain-positive, coccoid, alpha-haemolytic, Streptococcus species that were associated with meningoencephalitis in naïve weanling mice were further evaluated to confirm their taxonomic status and to determine additional phenotypic and molecular characteristics. Comparative 16S rRNA gene sequence analysis showed nearly identical intra-species sequence similarity (≥99.9 %), and revealed the closest phylogenetically related species, Streptococcus acidominimus and Streptococcuscuniculi, with 97.0 and 97.5 % sequence similarity, respectively. The rpoB, sodA and recN genes were identical for the three isolates and were 87.6, 85.7 and 82.5 % similar to S. acidominimus and 89.7, 86.2 and 80.7 % similar to S. cuniculi, respectively. In silico DNA-DNA hybridization analyses of mouse isolate 12-5202T against S. acidominimus CCUG 27296T and S. cuniculi CCUG 65085T produced estimated values of 26.4 and 25.7 % relatedness, and the calculated average nucleotide identity values were 81.9 and 81.7, respectively. These data confirm the taxonomic status of 12-5202T as a distinct Streptococcus species, and we formally propose the type strain, Streptococcusazizii 12-5202T (=CCUG 69378T=DSM 103678T). The genome of Streptococcus azizii sp. nov. 12-5202T contains 2062 total genes with a size of 2.34 Mbp, and an average G+C content of 42.76 mol%.
Insights
A novel catalase-negative Streptococcus species, previously linked to mouse meningoencephalitis, has been identified. Genetic and genomic analyses confirm it as a distinct species, Streptococcus azizii sp. nov.
Area of Science:
- Microbiology
- Bacteriology
- Genomics
Background:
- Three novel catalase-negative, Gram-positive coccoid Streptococcus isolates were previously associated with meningoencephalitis in mice.
- Further characterization was necessary to confirm the taxonomic status and identify unique phenotypic and molecular features of these isolates.
Purpose of the Study:
- To confirm the taxonomic status of three novel Streptococcus isolates.
- To determine additional phenotypic and molecular characteristics of these isolates.
- To formally propose a new species within the Streptococcus genus.
Main Methods:
- Comparative 16S rRNA gene sequencing was performed.
- Phylogenetic analysis included rpoB, sodA, and recN gene sequencing.
- In silico DNA-DNA hybridization and average nucleotide identity (ANI) calculations were utilized.
- Genomic analysis determined genome size, gene content, and G+C content.
Main Results:
- 16S rRNA gene sequence analysis showed ≥99.9% intra-species similarity and <97.5% similarity to related species (S. acidominimus, S. cuniculi).
- rpoB, sodA, and recN gene similarities further supported distinct species status.
- In silico DNA-DNA hybridization (<26.4%) and ANI (<81.9%) values confirmed the isolates represent a novel species.
- The genome of the type strain (12-5202T) is 2.34 Mbp with 2062 genes and 42.76% G+C content.
Conclusions:
- The data confirm the isolates represent a distinct Streptococcus species.
- The new species is formally proposed as Streptococcus azizii sp. nov., with type strain 12-5202T.
- This finding expands the known diversity within the Streptococcus genus and provides a reference for future studies.
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