Demonstration of Listeria monocytogenes by Immunohistochemistry in Formalin-Fixed Brain Tissues from Natural Cases of Ovine and Bovine Encephalitis

CAMPERO CM; ODEÓN AC; CIPOLLA AL; MOORE DP; POSO MA; ODRIOZOLA E

Journal of Veterinary Medicine Series B

Blackwell

Lugar: Berlin; Año: 2002 vol. 49 p. 1 - 5

0931–1793

In the present work, evidence of Listeria monocytogenes antigens based on the avidin–biotin complex (ABC) immunoperoxidase technique was performed on formalin-fixed central nervous system tissues (CNS) from a total of 23 natural cases of encephalitis (four ovine and 19 bovine). Listeria monocytogenes serotype 4 was isolated from 10 of 17 cultured specimens. Meningoencephalitis characterized by focal necrosis, microabscesses, perivascular cuffing, and gliosis with presence of macrophages and/or neutrophils was observed at histological examination. Positive L. monocytogenes antigens were successfully identified by immunohistochemistry (IHC) in the CNS of all 23 cases. Paraffin-embedded tissues assayed were stored up for 17 years. Morbidity of the outbreaks was between 0.3–3% and 0.1–1% for ovine and bovine cases, respectively. In all the ovine cases, flocks involved were under extensive grazing conditions. In nine of the 19 bovine cases (47.3%), supplementation with corn silage was used. The ABC test can help as a practical tool for the diagnosis of natural cases of L. monocytogenes encephalitis on formalin-fixed specimens from ovine and bovine.