Abstract

Samples of beef, pork, goat meat, poultry, fish and vegetables purchased from a local market located in Nsukka, Enugu State, Nigeria were examined for the presence of Listeria species. Surface swab samples taken from butchers’ tables as well as soil samples from the field where cows and pigs were kept before slaughter were examined. Listeria species were isolated from all samples except the pork and goat meat samples. The highest incidence (100%) was observed in the soil and surface swab samples, respectively, followed by the vegetable samples (85%) and the beef samples (80%). Only Listeria monocytogenes and Listeria ivanoviiwere pathogenic to test animals causing death within five days. L. monocytogenesinduced pathological changes characterized by abscesses in the liver, pericarditis and frank haemorrhage in the kidneys. The most notable change was the accumulation of mononuclear cells in the loose connective tissue surrounding the bile ducts. This study shows that there is a high incidence of listerial organisms in various key elements of the Nigerian environment, including soil and foods of both animal and plant origin, which may pose a health risk for high-risk individuals. The study goes further to establish the major target organs of attack of the pathogenicListeria species.

Key words: Listeria monocytogenes, pathogenicity, histopathology.

Abbreviation

UVM, University of Vermont broth; LMBA, Listeria monocytogenesblood agar; TSA, trypticase soy agar; TSBYE, trypticase soy broth plus yeast extract; RTE, ready-to-eat.