Antibiotic resistance and molecular characteristics of extended-spectrum beta-lactamase-producing Escherichia coli isolated from fish pond

Recently, extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli was isolated from cultured striped catfish, red tilapia and wild fish in Mekong Delta, Vietnam. ESBL genes are located on plasmids, facilitating their spreads among Gram-negative bacilli bacteria species. To better understand the dissemination of resistance genes in aquatic system, the antimicrobial susceptibility patterns and the molecular characteristics of ESBL-producing E. coli isolates were investigated by disk diffusion method and polymerase chain reaction. The results indicated that: (i) the proportion of antibiotic resistance of ESBL-producing E. coli was relatively high in most type of antibiotics except meropenem and cefoxitin; Considerably, multiple drugs resistance was recorded at high percentage, including 100% for ESBL-producing E. coli isolates of snakehead fish, 90% depended on the figure for striped catfish, 85% for ESBL-producing E. coli isolates of red tilapia and 50% for that of wild fish (ii) the number of ESBL-producing E. coli isolates carrying multiple ESBL genes were 90%, with significantly higher than those of carrying single ESBL gene at just 10%. In addition, the B2 virulence group was mainly isolated from wild fish, which was higher compared to groups of cultured fish (iii) the majority of isolates harbored multiple sulfonamides resistance genes (72.2%), which was significantly higher compared to the percentages of isolates carrying single genes (27.8%). The study illustrated that there were the significant widespread of antibiotic-resistant genes of ESBL-producing E. coli as well as a considerable ratio of multidrug resistance.