title: Multi-Drug Resistance Mediated by Class 1 Integrons in Aeromonas Isolated from Farmed Freshwater Animals.
abstract: Aeromonas is regarded as an important pathogen of freshwater animals but little is known about the genetics of its antimicrobial resistance in Chinese aquaculture. The aim of this study was to investigate the presence of integrons and characterize multidrug resistant Aeromonas spp. isolated from diseased farmed freshwater animals. These animal samples included fish, ornamental fish, shrimp, turtles, and amphibians which were collected from 64 farms in Guangdong province of South China. One hundred and twelve Aeromonas spp. isolates were examined for antimicrobial resistance phenotypes and the presence of class 1 integron sequences. Twenty-two (19.6%) of these isolates carried a class 1 integron comprising six different gene insertion cassettes including drfA12-orfF-aadA2, drfA12-orfF, aac(6')-II-bla OXA-21 -cat3, catB3, arr-3, and dfrA17. Among these, drfA12-orfF-aadA2 was the dominant gene cassette array (63.6%, 14/22) and this is the first report of aac(6')-II-bla OXA-21 -cat3 in an Aeromonas hydrophila isolate from a Chinese giant salamander (Andrias davidianus). All the integron-positive strains were resistant to more than five agents and 22 contained other resistance genes including bla CTX-M-3, bla TEM-1, aac(6')-Ib-cr, and tetA. All integron-positive isolates also contained mutations in the quinolone resistance determining regions (QRDR). Our investigation demonstrates that freshwater animals can serve as a reservoir for pathogenic Aeromonas strains containing multiple drug-resistance integrons. This data suggests that surveillance for antimicrobial resistance of animal origin and a prudent and responsible use of antimicrobials in aquaculture is necessary in these farms.
authors.affiliation: Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences Guangzhou, China.
authors.forename: Yuting
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Pearl River Fisheries Research Institute, Chinese Academy of Fishery SciencesGuangzhou, China; Office of Aquaculture Technology Extension, Foshan Institute of Agricultural SciencesFoshan, China.
authors.forename: Yali
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences Guangzhou, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences Guangzhou, China.
authors.forename: Aiping
authors.initials: A
authors.lastname: Tan
authors.affiliation: Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences Guangzhou, China.
authors.forename: Ruiquan
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences Guangzhou, China.
authors.forename: Li
authors.initials: L
authors.lastname: Luo
keywords: Aeromonas; class 1 integron; freshwater animal; multidrug resistance; resistance genes