Aerolysin gene characterization and antimicrobial resistance profile of Aeromonas hydrophilaisolated from milkfish (Chanos chanos) in Gresik, Indonesia

Background and Aim: Motile Aeromonassepticemia is a crucial disease in freshwater fish. Aeromonas hydrophilais
a disease agent associated with sporadic fish mortality, food safety, and public health. This study aimed to estimate the prevalence and the presence of the aerolysin gene and antimicrobial resistance profile of A. hydrophilaisolated from milkfish in Gresik, Indonesia.

Materials and Methods: A total of 153 milkfish gill samples were collected from 16 locations in Gresik and then cultured
and identified using biochemical tests. The aerolysin gene was investigated using a polymerase chain reaction, and
antimicrobial resistance profiles of the recovered isolates were investigated.

Results: Of the 153 examined samples, 35 (22.9%) were confirmed positive for A. hydrophilaand 22 (62.9%) presented
the aerolysin gene. The recovered isolates were resistant to the following antibiotics: Amoxicillin (62.9%), tetracycline
(60%), streptomycin (54.3%), cefotaxime (51.4%), gentamycin (31.4%), kanamycin (28.6%), erythromycin (25.7%),
chloramphenicol (20%), and trimethoprim (14.3%). Meanwhile, only ciprofloxacin, nalidixic acid, and imipenem were
indicated as susceptible.

Conclusion: The presence of the aerolysin gene is vital in determining the virulence of A. hydrophila. The study results indicated a high aerolysin gene prevalence. In addition, this study emphasized antibiotic use monitoring, food safety improvement, and negative impact reduction on human health and the environment.