Isolation and Characterization of a Novel Alpha-Hemolytic Streptococcus spp. from the Oral Cavity and Blood of Septicemic Periparturient Immunodeficient Mice

Comp Med. 2023 Sep 11. doi: 10.30802/AALAS-CM-23-000020. Online ahead of print.ABSTRACTMISTRG is an immunodeficient mouse strain that expresses multiple human cytokines that support hematopoietic stem cell maintenance and myelopoiesis. While establishing a breeding colony of MISTRG mice in a dedicated barrier room, 6 cases of death or disease occurred in pregnant or postpartum mice. Clinically, this manifested as hunched posture, dyspnea, and 1 case of emaciation with ataxia. Pathologic analysis of 7 mice revealed multisystemic necrosuppurative inflammation variably affecting the uterus and placenta, joints, meninges, inner and middle ears, kidneys, and small intestine. Bacteria cultured from the blood of septic mice were identified with 89% probability by the Vitek 2 identification system as Streptococcus sanguinuswith atypical biochemical parameters; the API 20E/NE system fully differentiated the isolates as a novel Streptococcusspecies. MALDI Biotyper-based mass spectrometry also indicated that the phenotype represented a novel Streptococcusspp. Sequencing revealed that the full-length 16S rRNA gene identity was below 97% with known Streptococcus species, including the 2 closest species Streptococcus acidominimus and Streptococcus azizii. We propose the name Streptococcus murisepticum spp. nov to our novel isolates. All male mice in this colony remained healthy despite their association with diseased female mice. Overall, 19% of the colony carried the novel Streptococcus i...
Source: Comparative Medicine - Category: Zoology Authors: Source Type: research