Pangasius Hypophthalmus Viscera as a Potential Vector of Bacterial Cross-Contamination and Resistance of Escherichia coli to Antibiotics

Abstract

The viscera of Pangasius fish was studied to provide baseline information about the presence of antibiotic-resistant E. coli on it. This aimed to assess the possible resistance of bacterial pathogens to antibiotics and cross-contamination into the fish's muscles during processing, as well as to evaluate the effect of starvation on the microbial loads of Pangasius fish viscera. The resistance of E. coli was tested against 15 antimicrobial agents using the disk diffusion method. The findings revealed that starvation reduced microbial loads on the viscera compared to non-starvation Pangasius. LAB, coliforms, and E. coli count on viscera of non-starved Pangasius were 7.0±0.5, 5.5±0.9 and 5.4±1.0 log CFU g-1, whereas those of the starved fish were 2.6±0.8, 3.8±0.4 and 3.1±0.3 log CFU g-1, respectively. A total of 55 E. coli isolated from Pangasius viscera were tested for antimicrobial susceptibility as stated above. Surprisingly, 69.09% of E. coli isolates were multi-antibiotic resistant from three to fifteen antibiotics tested. A high level of resistance to ampicillin (63.64%), ceftazidime (69.09%), nalidixic acid (78.18%) was observed. More importantly, 9.09% of the E. coli isolates were resistant to all kinds of antibiotics tested. As E. coli is a potential vector for transfer of antibiotic resistance gene, causing cross-resistance with human enteric pathogens, there is a need for both the prudent use of these antimicrobial agents in aquaculture and stringent appropriate infection control in the processing chain in Vietnam.