ABSTRACT
The present study aims at quantitatively assessing the risk associated with Salmonella in lettuce (Lactuca sativa) consumed in Benin (West Africa). To that end, a survey was conducted involving 550 respondents to determine the conditions under which the product is handled along the supply chain and its consumption pattern. The prevalence and concentration of Salmonella in lettuce were collected from the literature. The consumption data and the data on Salmonella concentrations in lettuce were combined to estimate the exposure to Salmonella using a probabilistic risk assessment method. The @Risk software package (Palisade USA) was used to run Monte Carlo simulations with 10,000 iterations. Three dose-response models were used to assess the risk of salmonellosis. Different scenarios were tested to identify factors that could influence the risk of salmonellosis. The results showed that lettuce is exposed to temperature abuse under inappropriate hygienic conditions. In 90% of the cases, the exposure to Salmonella was between 3 and 7 log CFU/serving. The risk of salmonellosis per serving varied from 7.7% to 95% depending on the dose-response used with the scenario taking into account the current handling conditions of the lettuce. In contrast, when considering the scenario where the cold chain is respected along the supply chain, the risk of salmonellosis varied from 0% to 3.3% depending on the dose response used. The study highlights the importance of the cold chain, good agricultural practices and good hygienic practices to reduce exposure to Salmonella through the consumption of lettuce and thus the risk of salmonellosis.
ABSTRACT
Two hundred (200) presumptive isolates of Bacillus collected at different fermentation time from spontaneous fermented samples of afitin; iru and sonru produced in three different regions of Benin were identified at species and strains levels. ITS-PCR-RFLP revealed that 79of the isolates were really identified as Bacillus; 5as Staphylococcus and 16as unidentified bacteria. The 16S rDNA sequencing showed that 74.7of the Bacillus belonged to the B. subtilis group and 25.3to the B. cereus group. Additional biochemical tests and API 50 CHB system applied to 50 isolates randomly selected from the B. subtilis group divided the latter into 80typical B. subtilis and 20typical B. licheniformis; which showed different PFGE-RFLP band patterns. Strains belonging to the B. cereus group were differentiated by PCR with specific primers BCW1F and BCW1R and specific enzymes EcoRI; Sau3AI and RsaI. All strains of the B. cereus group; except one; were found to be typical B. cereus. This work showed the predominance of B. subtilis in afitin; iru and sonru along the fermentation process