A study on the antimicrobial resistant bacteria in fish culture zones in Hong Kong

Abstract

In recent years, there is a global concern on the emergence of antimicrobial resistance bacteria in environment. A major root cause leading to the presence of antimicrobial resistance bacteria in marine environment is the direct administration of antimicrobial agents to treat infection in marine resources by mariculturists. Transmission of antimicrobial resistance bacteria from environment to human can then be caused by the ingestion of uncooked seafood. Therefore, this study aims at investigating the antimicrobial resistance of pathogenic bacteria in Hong Kong fish culture zones. Water samples, sediment samples as well as fish intestine samples were obtained from five marine fish culture zones in Hong Kong, including Ma Wan, Wong Wan, Yin Tin Tsai, Sok Kwu Wan and Kau Sai. Pathogenic bacteria from these samples were identified using Vitek® mass spectrometry and their antimicrobial resistance was tested using antibiotics susceptibility test according to the guidelines provided by the Clinical & Laboratory Standards Institute. In this study, Vibrio spp. (70.1%) was found to be the dominating genus of pathogenic bacteria in the samples collected from marine fish culture zones. Bacillus spp. (20.8%), Photobacterium damselae (6.3%), Escherichia coli (2.1%) were also isolated. The results from this study shows that pathogenic bacteria isolated from marine fish culture zones in Hong Kong generally demonstrated high resistance to neomycin (87.5%), penicillin (85.4%) and ampicillin (79.2%). In addition, it is discovered that there was no spatial variation on the presence of antimicrobial resistance bacteria among the five marine fish culture zones. All the five marine fish culture zones demonstrated similar percentage of antimicrobial resistance bacteria when compared to that found from their respective control points. The results implied that the use of antibiotics to treat fish diseases by mariculturists does not contribute significantly to the development of antimicrobial resistance bacteria in marine fish culture zones in Hong Kong. Development of antimicrobial resistance within fish culture zones area is probably brought about by the inflow of marine water from open sea area into the fish culture zones. The antimicrobial resistance pathogenic bacteria isolated from culture fish’s intestine in this study also suggests potential transmission of antimicrobial resistance from marine environment to human environment.