Listeria spp. in Raw Cow and Goat Meat in Port Harcourt, Nigeria

Aims: To determine the occurrence of Listeria monocytogenes and other Listeria spp. in raw cow and goat meat.

Study Design: This work was based on a completely randomized design with two replication and the average values calculated for mean comparison.

Place and Duration of Study: Department of Microbiology, University of Port Harcourt, Nigeria and Nigeria Institute of Medical Research, Yaba, Lagos, Nigeria. Isolation of Listeria spp. was between March 2011 and February 2012.

Methodology: In this study, a total of 240 raw cow and goat meat samples were analyzed for the presence of Listeria monocytogenes and other Listeria species. The techniques recommended by the United State Department of Agriculture (USDA) revised and the Health Products and Food Methods of the Government of Canada were employed using Fraser broth and polymixin acriflavin lithium chloride ceftazidime aesculin mannitol (PALCAM) agar.

Results: The results of conventional and polymerase chain reaction (PCR) characterization of the isolates revealed that 81 samples (33.75%) were positive for Listeria spp. The highest prevalence of Listeria was found in cow flesh samples (19 of 36 samples; 52.78%) followed by cow intestine samples (8 of 20; 40%) and least was goat kidney samples (5 of 28; 17.86%). Out of the 310 characterized Listeria spp., L. monocytogenes were 4(1.29%). Other species isolated were L. innocua 20(6.45%), L. ivanovii 4(1.29%), L. seeligeri 72 (23.23%), L. welshimeri 139 (44.84%) and L. grayi 71(22.90%). No L. monocyogenes was isolated from cow samples. A higher incidence was noted during the raining season 216 (69.68%) than the dry season 94(30.32%).

Conclusion: This study demonstrated the occurrence and distribution of Listeria species in retail raw cow and goat meat in Port Harcourt, Nigeria.