Occurrence and characterization of Proteus mirabilis from infected farmed African catfish in Ogun State, Nigeria

Bacterial pathogens are the causative agents of some of the most serious disease problems in cultured fish causing mortalities and severe economic losses. This study was conducted to determine the occurrence and characterization of Proteus mirabilis from infected farmed African catfish in Ogun State, Nigeria.

The bacteria were isolated from diseased farmed African catfish (Clarias gariepinus, n=128) with clinical signs of skin haemorrhages, ulceration, and ascites purposively sampled from farms within three senatorial districts namely Ogun East (OE; n=76), Ogun Central (OC; n=30) and Ogun West (OW; n=22) in Ogun State. The isolates were identified based on morphological characteristics, biochemical tests, and 16S rRNA gene characterisation. The 16S rRNA gene sequences were analysed using BLAST, submitted to the NCBI database, and an accession number was generated.

The occurrence of Proteus mirabilis in infected Clarias gariepinus was 13.16%, 25%, and 31.25% in OE, OC, and OW, respectively. A significantly higher incidence was recorded in OW compared to other areas. All the Proteus mirabilis isolates were motile, gram-negative, short rod, non-lactose fermenter bacteria that showed positive catalase reactions, negative oxidase, and positive for methyl-red. The Proteus mirabilis isolates (OP 594726.1) were closely related to isolates from Pakistan, Italy, and India

We conclude that Proteus mirabilis colonises farmed Clarias gariepinus in Ogun State, Nigeria and the identified strain showed an evolutionary relationship with known pathogenic NCBI reference strains from other countries.