Antibiotic susceptibility and molecular characterization of <i>Aeromonas hydrophila</i> from grass carp

Abstract

Abstract Aeromonas hydrophila is the leading cause of fish borne outbreaks and also represents a major threat to human health worldwide. This bacterium harbors many virulence factors such as aerolysin, elastase, and lipase genes. The extensive use of antibiotics is a contributing factor to the increasing incidence of antimicrobial‐resistant A. hydrophila . In the current study, we aimed to determine the incidence and features of A. hydrophila in grass carp in south China. We found 63 (31.5%) A. hydrophila isolates through investigation of 200 samples from five provinces in south China. All isolates were analyzed for virulence genes by polymerase chain reaction (PCR), antibiotic susceptibility analysis was carried out using the disk diffusion method, and molecular typing was performed using enterobacterial repetitive intergenic consensus sequence PCR (ERIC‐PCR). The results showed that the positive for aerolysin, elastase, hemolysin, and lipase gene were 71.43, 46.03, 0.00, and 55.56%, respectively. Antimicrobial susceptibility results indicated that most strains were resistant to ampicillin (95.24%), tetracycline (88.89%), and streptomycin (79.37%). A lot of multiple antibiotic resistance were found. The isolates were grouped into five clusters by ERIC‐PCR and shown the genetic diversity. Thus, our findings demonstrated the presence of A. hydrophila from grass carp, provided insights into the dissemination of antibiotic‐resistant strains, and improved our knowledge of microbiological risk assessment in this bacteria. Practical applications Investigating the prevalence of Aeromonas hydrophilia isolates from grass carp could improved for assuring this microbial safety on food. In this study, antibiotic susceptibility, virulence genes, and molecular subtyping were selected to comprehensive analyze A. hydrophilia isolates. As grass carp are common and popular fish choices in China, therefore the continuous monitoring of this pathogens are vital to ensure the safety.