Taxonomic and Biochemical Analysis of Enterobacteria Isolates Isolated from Some Vegetables and Irrigation Water in Niamey, Niger

Enterobacteriaceae is one of the most important bacterial families in human pathology. This family includes numerous species, most of which are normal hosts in the digestive tract of humans and animals. The aim of this study was to characterize the taxonomy and diversity of enterobacteria contaminating vegetables in Niamey. A total of 124 vegetable samples and 29 irrigation water samples were collected and analyzed. Enterobacteria were enumerated in accordance with ISO 21528-1 and the biochemical characteristics were determined. The results showed a high abundance of enterobacteria in vegetables, around 5.58 Log10 CFU/g (onion). Enterobacteriaceae were more abundant in market samples than in field samples. Secondly, several species of enterobacteria were isolated, with sixty (60) isolates identified, divided between eighteen (18) species belonging to the enterobacteria family, including twenty (20) isolates of Salmonella, ten (10) isolates of Escherichia coli and seven (7) isolates of Serratia. Lettuce samples were more contaminated with Salmonella spp. (15.22%) and tomato with Enterobacter cloacae (4.35%). A certain biochemical similarity was observed between the different enterobacteria species identified. Whatever the type of vegetable considered, the enterobacteria loads obtained, it should be exceed the microbiological criteria for vegetables.  As a result, the sanitary quality of these vegetables is low. It is therefore essential to make producers and retailers aware of the need to strictly adhere to good hygiene practices in order to produce healthy vegetables. To characterize the risk associated with consumption of this vegetable, it would be important to determine the profile and antibiotic resistance genes of these Enterobacteriaceae species.