Microbiological, Biochemical and Molecular Characterisation of Strains Isolated from Smoked and Dried Clarias gariepinus Fish Sold at the N’Djamena Market (Chad)

Abstract

In Africa, and particularly in Chad, fish consumption remains relatively low despite its richness in proteins, vitamins, and essential fatty acids. In this study, a total of 16 samples of processed Clarias gariepinus fish (smoked and dried), collected from the Dembé and Taradona markets in N’Djamena, were analyzed. The main objective of this work is to characterize, from a microbiological, biochemical, and molecular perspective, the strains isolated from these processed fish. Microbiological analysis was carried out using standardized methods. Presumptive Escherichia coli strains were identified using API 20E test strips along with the API WEB software. Antibiotic susceptibility was assessed in accordance with the guidelines of the Antibiogram Committee of the French Society for Microbiology (CA-SFM). Furthermore, the isolated E. coli strains were subjected to molecular analysis by PCR. The microbiological quality assessment revealed the presence of E. coli strains at an average concentration of 1.3 × 10 3 ± 3.2 × 10 2 CFU/g. The antibiogram showed the presence of resistant, intermediate, and susceptible strains to the tested antibiotics. The strains were confirmed by PCR, validating the initial identification. These results highlight the need for strict control measures and awareness campaigns on good hygiene practices in fish processing, in order to improve the sanitary quality of the marketed products and protect consumer health.