Low Concentrations of Antibiotics Alter Microbial Communities and Induce High Abundances of Antibiotic-Resistant Genes in Ornamental Water

Abstract

Antibiotic resistance poses a significant threat to the public health domain. A favorable platform for generating and disseminating antibiotic-resistant genes (ARGs) and antibiotic-resistant bacteria (ARB) is provided by landscaped fish ponds created by urbanization. This research delved into the effects exerted by different concentrations of specific antibiotics, namely tetracycline and ciprofloxacin, on the microbial community composition present in water samples obtained from a landscape pond. Additionally, we analyzed the abundance of ARGs and the class 1 integron-integrase gene (intI1), and identified potential hosts of ARGs. The results indicated that the consistent administration of antibiotics significantly influenced the microbial community structure, resulting in variations within both bacterial communities and functionalities. Furthermore, the absolute quantities of ARGs, including tetA, tetC, qnrA, and qnrS, as well as the integrase gene intI1, exhibited augmentation in response to varying types and concentrations of antibiotics. Notably, the regular input of low concentrations of antibiotics produced higher levels of abundance of ARGs than the regular input of higher concentrations of antibiotics. The use of different types of antibiotics led to diverse host bacteria structures.

Impact of Prophylactic Antibiotic Use in Ornamental Fish Tanks on Microbial Communities and Pathogen Selection in Carriage Water in Hong Kong Retail Shops

“…The antibiotic use in the ornamental fish industry has led to the selection of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the ornamental fish trade globally [ 7 , 8 ]. For instance, our previous study revealed that Aeromonas and Pseudomonas spp.…”

“…isolated from carriage water samples demonstrated resistance to over 15 types of antibiotics, and most of them carried multiple ARGs, such as qnrS2 , intl1 , tetD , and tetE [ 6 ]. Moreover, it has been documented that antibiotics administered at subtherapeutic levels can induce the development of an environmental resistome [ 8 , 10 ]. For example, enrofloxacin at concentrations above 0.064 ng L −1 can result in the selection of ARB [ 11 ].…”