Molecular Characterization of Salmonella Species Isolated from Animal Sources in Southern-Taraba State, North-East Nigeria

Aims: The purpose of this research was to detect the Salmonella invA gene from chicken’s droppings in Southern Taraba, North East Nigeria. The invasive “invA” gene facilitates the invasion of epithelial cells by Salmonella isolates.

Study Design: This study is experimental research involving ninety-eight (98) Salmonella isolates from chicken droppings in poultry farms and domestic chicken coops.

Place and Duration of Study: This research was carried out in Wukari, Donga, Ibi and Takum towns in Southern Taraba, North East Nigeria between November 2021 and May 2023. A total of 400 (Donga,100; Wukari, 100; Ibi, 100 and Takum, 100) Chicken droppings were collected from 40

(Donga, 10; Wukari, 10; Ibi, 10 and Takum, 10) small-scale poultry farms, and 100 (Donga, 25; Wukari, 25; Ibi, 25 and Takum, 25) Chicken droppings were sampled from 20 (Donga, 5; Wukari, 5; Ibi, 5 and Takum 5) domestic chicken coops and analyzed.

Methodology: Using standard microbiological techniques, Salmonella Shigella Agar (SSA) was used to confirm and validate 98 (Wukari; 36, Donga; 19, Ibi; 27, and Takum; 16) Salmonella isolates from stock culture. Isolates were further subjected to biochemical analysis. Boiling technique was used to extract the DNA of the 98 isolates. Salmonella invA gene amplification process was done using Polymerase Chain Reaction (PCR). Electrophoresis was done using agarose gel, and DNA band patterns were visualized with the aid of ultraviolent light (UV) showing different patterns and interpreted with the 100 bp DNA ladder.

Results: The results of this study indicate that the invA gene was detected in 80.6% (Wukari; 86.1%, Donga; 68.5%, Ibi;85.2%, and Takum; 75%) of the 98 Salmonella isolates with an amplicon size of 284bp. This finding implies that 19 isolates which did not show the targeted band are not invasive, and even if they are, other invasive genes may be liable.

Conclusion: The detection of the invasive invA invasive gene from Salmonella isolates from the fecal droppings of apparently healthy chickens from poultry farms and domestic chicken coops is really of great concern to public health. Unless a proper hygienic protocol and biosecurity measures are strictly adhered to where applicable in food processing chain, Salmonella isolates harboring the invA traits could be opportunistically invasive among immunocompromised individuals and children.