Antimicrobial susceptibilities of Aeromonasstrains isolated from various aquatic animals in Guangdong Province

Abstract:

112 Aeromonas strains were isolated from various aquatic animals at different time in Guangdong province. Kirby Bauer disc diffusion method was used to detect the resistance of 112 strains against 20 commonly used antimicrobial agents. Resistance rates were analyzed by WHONET 5.6 software. The overall resistance rates were highest for ampicillin (85.7%) and cephalothin (79.5%) followed by rifampicin (57.1%)，amoxicillin/clavulanic acid (51.8%)，streptomycin (49.1%)，sulfonamides (31.2%)，cefoxitin（28.6%），tetracycline (28.6%) and trimethoprim/sulfamethoxazole (21.4%). Aeromonas isolates were suseptible to most of antimicrobial agents and a low incidence (<10%) of resistance to imipenem (0.9%)，nitrofurantoin (0.9%), ceftriaxone (1.8%)， cefotaxime (2.7%) and amikacin (3.6%) were observed. Although 46.6% of isolates displayed nalidixic acid resistance，majority of isolates were very susceptible to other kinds of fluroquinolones. Compared with the resistance rates of different antimicrobial agents from different origins of aquatic animals, fluroquinolones and cephalosporins resistance was more prevalent in strains from reptiles, amphibians and ornamental fishes than those from farm fishes and shrimps. Our results showed that antimicrobial resistant Aeromonas were widespread in the aquaculture in Guangdong and show various resistant rates to different antimircrobial agents. There is a need to build a national surveillance system of antimicrobial resistance in aquaculture.