Botryomycosis in NOD.CG-PRKDCSCID IL2RGTM1WJL/ SZJ mice: a focal outbreak in an experimental colony

GABRIELA PATACCINI; PAOLA ROJAS; ERNESTO GULIN

Mar del Plata

Congreso; Reunión anual de sociedades de Biociencia SAIC SAFE SAB SAP; 2019

NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice were originally purchased from Jackson Laboratory and maintained under conventional closed barriers in individually ventilated cages (Tecniplast®) with controlled temperature (20-22°) and relative humidity (50–70%) in a 12:12 h light: dark cycle. The animals were fed with autoclaved standard diet and carbon activated filtered water ad libitum. Cages were filled with sterile wooden chips and corn. The Institutional Animal of Care and Use Committee (IACUC) approved the experimental protocols for the conducted studies. Mice (n=9; 6-12 months-old) included in patient-derived xenografts (PDX) studies exhibited solitary or multiple fibrose nodules of 0.50 cm, located near to the mouth and nose. Mice were also in poor body condition, weight loss, and ruffed coat. The cases appeared randomly in cages for over five months. After clinical examination, differential diagnoses included bacterial or fungal infections, foreign body granuloma, sterile pyogranuloma, or neoplasia. Since the body condition was getting worse, euthanasia was suggested, and animals were submitted to necropsy. The nodules presented fibroelastic consistency at the cutting. Macroscopic description concluded hepatosplenomegaly, pale diffuse liver and uterus, ovaries and gastrointestinal tract inflammation, with coagulated blood in stomach content.At histological examination, there was multifocal dermatitis as a severe inflammatory reaction in the dermis, with diffuse bacteria colonies, accompanied by a fibrillar acidophilic material compatible with a Splendore-Hoeppli reaction, surrounded by neutrophils and piocytes and a moderate presence of epitheloid macrophages. The diagnostic was botriomycosis, probably due to Staphylococcus spp. This is the first report of botryomycosis or bacterial pseudomycetoma in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice. Regarding their combined immunodeficiency condition, skin nodules should be early diagnosed, taking account botryomycosis as a differential diagnosis. Strict housing barriers and procedures have to be taken to the extreme in order to avoid or reduce the presentation and severity of this concomitant pathology.