LISTERIA SPECIES AND OCCURRENCE IN RETAILED SMOKED FISH SAMPLES IN SELECTED OTA MARKETS, OGUN STATE, NIGERIA

This study investigated the prevalence of Listeria spp. in 72 samples of smoked species of codfish (Gadus morhua), herring (Clupea harengus), catfish (Clarias gariepinus) and mackerel (Scomber scombrus) sampled from Sango (SA), Oju-ore (OO), Oja-Oba, Iyana-Iyesi (II), Iju (IJ) and Atan (AT) markets, all in Ota, Ogun State, Nigeria. Adopting Oxoid Listeria Precis method, Listeria spp. were isolated and characterized morphologically and biochemically. Of the 72 samples, 8 (11.11%) tested positive. Listeria ivanovii (1.38%), L. grayi (2.78%), L. monocytogenes (2.78%) and L. innocua (4.16%) were identified in all the fish samples except Clupea harengus. Antibiotic sensitivity tests revealed all the isolates resisted Imipenem, Cefuroxime, Amoxillin and Cefexine but susceptible to Levofloxacin: 34mm (L. grayi) to 39mm (L. ivanovii), Ciprofloxacin: 25mm (L. monocytogenes) to 36mm (L. grayi) and Ofloxacin: 20mm (L. ivanovii) to 29mm (L. innocua). Occurrence of these bacteria could indict the safety of the smoked fish products for consumption. The low percentage occurrences coupled with the high antibiotic susceptibility may, however, relieve the potential consumers of the menace of the associated health risks the consumption of such fish products could pose. The required control measures to prevent the occurrence of especially Listeria monocytogenes and other species in the processing and distribution chains of these smoked fish products should be prioritized.