Antibiotic resistance is one of the most important environmental issues in the world. The relationship between antibiotic use and antibiotic resistance of environmental bacteria were investigated using metagenomic analysis of antibiotic resistance genes (ARGs) in the sediments collected from the Western Pacific (WP) and the Pearl River Estuary (PRE) in this work. The result indicated that multidrug resistance genes (MRGs) were accounted as 77.8% of the total ARGs in the WP sediments

and the PRE sediments as 27.2%. ARGs in the PRE sediments were characterized by increasing abundance of ARGs specific to common antibiotics (e.g.

sulfonamides

macrolides

aminoglycoside

etc.) and decreasing relative percentage of MRGs. A total of 45 ARG subtypes were identified in the sediments

and thereof 7 subtypes

including acrB

amrB

bacA

ceoB

macB

mexB and smeE

concurrently existed in all sediments. Approximately 0.3% of ARGs in the WP sediments were potentially carried by the plasmids. Different from the WP

relative percentage of plasmidcarrying ARGs in the PRE sediments was higher than 40%. It was suggested that the abundance and diversity of ARGs in the PRE environment were substantially increased probably due to wide use of antibiotics in the nearby regions.