Investigating the Prevalence, Antibiotic Resistance Pattern, and Serotyping of Shigella Isolates from Traditional and Industrial Olivier Salads

Background: Food-borne diseases are one of the major problems in developing countries. This study aims to investigate the prevalence, antibiotic resistance pattern, and serotyping of Shigella isolates from Olivier salad. Methods: ۱۵۰ samples of Olivier salad, including ۵۰ industrial samples from ۱۰ different available brands in Tehran's shops and ۱۰۰ traditional samples from Tehran's southern regions, were randomly obtained between April to October of ۲۰۲۱. These samples were examined for bacterial isolation and identification, which was finally confirmed by the API-۲۰E kit. Then, a serological reaction was used to confirm Shigella and determine the species. The antibiotic resistance pattern of isolates was evaluated according to Clinical and Laboratory Standards Institute (CLSI, ۲۰۲۱) instructions by the Kirby-Bauer method. Results: Among these samples, ۱۰ isolates (۶.۶%) of Shigella were isolated, of which ۶ (۴%) belonged to serogroup D (Shigella sonnei), ۳ (۲%) to serogroup B (Shigella flexneri), and ۱ isolate (۰.۶۶%) belonged to serogroup C (Shigella boydii). This study showed that all Shigella isolates were related to traditional Olivier salad and were not Shigella spp. isolated from the industrial salad. Other bacteria isolated from traditional salad included Escherichia coli, Salmonella, Pseudomonas, Klebsiella, and Citrobacter. Multidrug resistance (MDR) was not observed in all isolates, and among ۱۰ isolates of Shigella, ۴۰%  showed complete resistance to ampicillin, but other isolates showed ۶۰% intermediate resistance to this antibiotic. No resistance was observed for other tested antibiotics. Conclusion: The difference between the level of contamination in both traditional and industrial samples of salad well indicates familiarity with sanitary protocols and standards provided to reduce the microbial load.

کلیدواژه ها:

Shigella ، Salads ، Drug resistance ، Bacterial antibiotic resistance ، Foodborne diseases.