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Updated: Jun 27, 2026

Screening Foodstuffs for Class 1 Integrons and Gene Cassettes
Published on: June 19, 2015
Identification and characterization of Class 1 integron resistance gene cassettes among Salmonella strains isolated
Ashraf A Khan1, Elizabeth Ponce, M S Nawaz
1Division of Microbiology, U.S. Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR 72079, USA. Ashraf.khan@fda.hhs.gov
Abstract:
A total of 210 Salmonella isolates, representing 64 different serovars, were isolated from imported seafood samples, and 55/210 isolates were found to be resistant to at least one antibiotic. Class 1 integrons from three multidrug-resistant Salmonella enterica strains (Salmonella enterica serovars Newport [strain 62], Typhimurium var. Copenhagen [strain 629], and Lansing [strain 803], originating from Hong Kong, the Philippines, and Taiwan, respectively) were characterized. Southern hybridization of plasmids isolated from these strains, using a class 1 integron probe, showed that trimethoprim-sulfamethoxazole and streptomycin resistance genes were located on a megaplasmid in strain 629. Our study indicates that imported seafood could be a reservoir for Salmonella isolates resistant to multiple antibiotics.

