Antimicrobial Resistance Pattern and Characteristics of Integrons in Escherichia Coli Strains Isolated from Aquatic Retail Products in Zhejiang Province, China

The aquatic retail products are among the potential reservoirs of antimicrobial resistant microorganisms. The main objective of this study was to analyze the antimicrobial susceptibility patterns and integrons and their associated Gene Cassettes (GCs) of Escherichia coli isolates from aquatic retail products. E. coli isolates were obtained from 450 aquatic retail products samples at different markets in Zhejiang Province, China. Antimicrobial resistance among the selected isolates was studied against 19 different antibiotics by disk diffusion method and all isolates were detected for the presence of integrase genes and Gene Cassettes (GCs) using PCR assays. The results showed that a total of 181 (40.22%) E. coli were obtained and the resistance pattern in the isolates was highly variable and significant differences were observed between seven antibiotics (p<0.05). Furthermore, 65.19% (118/181) of the isolates exhibited Multi-Drug Resistance (MDR) and the multiple resistance patterns were highly diverse with 77 different ones. Additionally, multiple-antibiotic resistance index values of more than 0.2 were determined in 62.43% of the isolates, which were diversely distributed in the three aquatic products. Of the 181 E. coli isolates obtained, 56 (30.94%) were positive for class 1 integrons and five (2.76%) were positive for class 2 integrons. Among these, 31 GCs with nine different arrays were detected in class 1 integrons and five GCs with two different arrays were detected in class 2 integrons. This study suggests that aquatic products may act as a reservoir and facilitate the dissemination of MDR.