Genotypic Identification of Extended-Spectrum β-Lactamase (ESBL) Producing Salmonella spp. Associated with Meat and Lettuce and Sales Practices that Contribute to Contamination of These Foods in Bobo Dioulasso

Background and Aims: Food contamination is often linked to diverse factors such as poor food preservation, culinary techniques, and the handling of products during marketing. These factors could facilitate the spread of bacteria which are among the primary causes of food borne infections in both developing and industrialized countries adding to public health burden. This study aims to highlight the epidemiology of Extended-Spectrum β-Lactamase (ESBL)-producing Salmonella strains in lettuce and charcuterie as well as to investigate sales practice that could aid food contamination.

Methods: The study was conducted at Bobo-Dioulasso from April to December 2021. A survey was carried out among 30 randomly selected lettuce sellers in 5 markets and 30 randomly selected charcuterie workers in 3 selected supermarkets. A total of 162 samples (90 lettuce and 72 charcuterie) were collected and screened for the presence of Salmonella using standard methods. Antibiotic susceptibility testing was carried out on the obtained Salmonella isolates using the Kirby – Bauer disk diffusion technique. Specific primers were used for the detection of the class 1 integrons, antibiotic resistance, and virulence genes by PCR.

Results: The quality of water used for keeping the lettuce fresh (wetting) and sellers’ hygiene were significantly associated with lettuce contamination (=14.21, P<0.001). For charcuteries, 66.7% and 33.3% of the structures surveyed use refrigerated trucks and vans for transportation, respectively. Salmonella was isolated from 12.35% (20/162) of the samples, i.e., 13.33% (12/90) of the lettuce samples and 11.11% (8/72) of the charcuterie samples (χ2 = 9.485; p < 0.005). Antibiotic susceptibility testing revealed that all the isolates were resistant to colistin while 70% (14/20) and 60% (12/20) were resistant to cephalothin and ampicillin, respectively. The int1, parE, parC, blaCTX-M, and blaTEM genes were detected among 70%, 65%, 60%, 45% and 40% of the isolates, respectively.

Conclusion: This study revealed that seller’s practice including handling and quality of water for wetting could significantly increase the risk of contamination on ready to eat vegetables including the presence of enteric pathogens such as Salmonella sp carrying various antibiotic resistance determinants which could pose public health risk. There is a need of sensitization and training for these sellers as the issue is a national public health problem.