Microbiological study on Listeria species isolated from some food products of animal origin

The study was carried out to investigate the presence of Listeria species in some food products of animal origin. A total of 200 different samples were collected including; milk (100), kariesh cheese (25), beef meat (25), hot dog (25) and Tilapia fish (25). The obtained results showed that the highest rate of isolation of Listeria was recorded in Tilapia fish (40%), followed by beef meat (28%) then raw milk (25%), Hot dog (24%) and finally kariesh cheese (20%). Distribution of Listeria isolated from raw milk clarified the identification of L. monocytogenes (2%), L. ivanovii (7%), L. innocua (5%), L. seeligeri (6%) and L. murrayi (5%), from kariesh cheese samples, L. monocytogenes (4%), L. ivanovii (8%), L. innocua (4%), and L. seeligeri (4%), from beef meat samples, L. monocytogenes (8%), L. ivanovii (4%), L. innocua (4%), L. seeligeri (4%) and L. welshimeri (8%), from Hot dog samples, L. monocytogenes (4%), L. ivanovii (8%) and L. welshimeri (12%) and finally, from Tilapia fish samples clarified the identification of L. monocytogenes (4%), L. ivanovii (12%), L. innocua (4%), L. seeligeri (4%) and L. welshimeri (16%). Finally, PCR was applied successfully to detect LM1 gene in identification of isolates of L. monocytogenes. The data obtained in this study provides useful information for assessment of the possible risk posed to Libyan consumers and will have a significant public health impact in Libya.