Abstract

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Plesiomonas sp is a facultative anaerobic, gram negative, oxidase positive, nonsporing, motile bacilli, that has been implicated in food and water borne diseases. This experiment was conducted to determine the incidence of this bacteria in catfish (Clarias gariepinus) and Tilapia (Oreochromis niloticus) sold in selected markets in Lagos State. A total number of 64 samples (fish) were collected from different locations between the months of August and September, 2018. 10g from each sample was serially diluted in 90 ml of sterile distilled water and 1 ml from 10-3 dilution was inoculated in duplicate on solidified inositol brilliant green bile agar. Plateswere incubated at 35°C for 24-48hr. Isolates were Identified based on culturalcharacteristics, Gram staining and biochemical characterization. The total viable count showed that catfish from location D (Iyana-Iba market) had the highest microbial load of 9.2×104 cfu/g while the lowest microbial load for catfish was recorded in location B (Igando market) with 1.0×104 cfu/g. The highest and lowest microbial load for tilapia samples were observed in location G (Oyingbo market) with 2.5 ×104 cfu/g and 0.7×104 cfu/g respectively. Antibiotics susceptibility test conducted showed that most of the isolates were multi-drug-resistant with multiple antibiotic resistance index above 0.2 risk limit. Hemolysis test also revealed varying zones of clearing confirming their ability to produce hemolysin. Plesiomonas sp is an organism of concern because of its ability to cause intestinal infections and could be a public health threat if ignored.

Keywords: Plesiomonas sp, seafood and antibiotic resistance