Antibiotic resistance bacteria in aquaculture sources in Johor, Malaysia

Abstract

The fast-growing aquaculture sector has served as the reservoir in promoting the emergence of antibiotic resistance mechanisms. This study aimed to isolate and identify the bacteria from aquaculture sources and water samples followed by identification of the multiple antibiotic resistance (MAR) bacteria. The fishes and water samples from Fisheries Research Institute (FRI), Kukup, Pulai, Pendas Laut, Sungai Melayu and Kong Kong rivers were collected and subjected to both phenotypic and genotypic identification via 16S rRNA sequencing and phylogenetic analysis. Colony morphology and Gram-stain appearances of the bacterial isolates were observed as preliminary identification. Antibiotic susceptibility test via disc diffusion was performed for each of the bacterial isolates. In this study, a total number of 133 bacterial isolates were obtained and it was discovered that the antibiotic resistance character occurred in 63 bacterial isolates. From 63 isolates, 90.48% were resistant to rifampicin, 80.95% to ampicillin and 65.08% to sulphafurazole. High number (26.98%) of MAR bacterial isolates were isolated from FRI, suggesting that the origin of the isolates to be of high antibiotic usage. From 63 MAR isolates, 61 of them showed different characteristics in terms of antibiotic resistance and phenotypic test, indicates these isolates were from different strains. The 61 different MAR strains were subjected to 16S rRNA sequencing and the findings revealed that majority of the bacteria species obtained were Bacillus spp. (Bacillus tropicus, Bacillus proteolyticus, Bacillus paramycoides, Bacillus cereus and Bacillus toyonensis), Pseudomonas spp. (Pseudomonas songnenensis, Pseudomonas pseudoalcaligenes, Pseudomonas plecoglossicida and Pseudomonas hibiscicola), Aeromonas spp. (Aeromonas caviae, Aeromonas hydrophila and Aeromonas rivipollensis), Acinetobacter spp. (Acinetobacter johnsonii and Acinetobacter modestus) and Enterobacter spp. (Enterobacter cloacae and Enterobacter xiangfangensis). The phylogenetic analysis in each location suggested that the bacteria strains obtained in this study were closely related to the strains aligned that obtained from National Center for Biotechnology Information (NCBI) according to the neighbour-joining phylogenetic tree analysis, but with the low bootstrapping number, they cannot be assigned accurately to a certain species due to its low discrimination. This study revealed the imprudent use of antibiotics in aquaculture may pose high risk of antibiotic resistance and is crucial to raise public awareness on it. Therefore, there is a need to control the usage of antibiotics in aquaculture to avert the occurrence of multiple antibiotic resistant bacteria and contribute to the antibiotic prescription policies in this country.