Detection of Listeria Species and Staphylococcus aureus in Smoked Fish Sold Within Ahmadu Bello University Main Campus Samaru, Zaria

Abstract

Hygiene practices in food processing plants are important determinants of food quality and safety. Poor hygiene practices may result in the contamination of foods and food products with pathogens, which means a serious risk to public health. This study was aimed at isolating and determining the antibacterial susceptibility profile of Listeria spp. and Staphylococcus aureus from smoked fish sold within Ahmadu Bello University Main Campus. A total of twenty-five (25) smoked fish samples were collected. Fifteen (15) samples, five each from Community market, Akenzua market and ICSA Ramat market were processed and inoculated on Mannitol Salt Agar for the isolation of Staphylococcus aureus. The remaining ten (10) samples were processed using stomacher and on Listeria Selective Agar (Oxford formulation) for the isolation of Listeria spp. The isolates were characterized based on their colonial morphology, Gram’s and biochemical reactions. In addition, agglutination test was carried out to further identify Listeria spp. Antibacterial susceptibility patterns of the isolates was determined using disc diffusion method. Staphylococcus aureus was isolated from all the 15 samples analyzed, giving an occurrence of 100%. However, only one Listeria spp. (Listeria ivanovii) was isolated from the 10 samples analyzed, with a 10% occurrence. All the S. aureus isolates were susceptible to most of the antibiotics, but four were resistant to rocephin and eight to ampiclox. The Listeria ivanovii isolate was also resistant to most of the antibiotics and susceptible to only two. The Multiple Antibiotics Resistance Index (MARI) of S. aureus isolates ranges from 0.2 to 0.4 while it was 0.75 for the Listeria ivanovii isolate. The study demonstrated that smoked fish sold in Ahmadu Bello University Main Campus were found to be contaminated and its consumption is potentially regarded as a health hazard, as such measures should be adopted to control it.

Keywords

• Smoked fish
• Isolation
• Listeria spp.
• Staphylococcus aureus
• Antibacterial susceptibility pattern