Listeria innocua isolated from a case of ovine meningoencephalitis

This paper reports a naturally occurring case of meningoencephalitis associated with Listeria innocua in a Polled-Dorset ewe. The ewe was one of a housed group of twenty-five, fed ad lib. on wrapped baled silage. L. innocua was isolated after one week from cold enrichment culture of brain and pituitary tissue. Its identity was confirmed by conventional biochemical tests, API Listeria (BioMerieux UK Ltd), the absence of hly and prfA genes using PCR assay and sequencing two variable regions of 16S rDNA. Histological examination demonstrated lesions of vasculitis and perivascular cuffing in the midbrain which were consistent with listeriosis although limited in distribution and severity.