Biochemical and Molecular Detection of Aeromonas Hydrophila Isolated from Infected Cyprinus Carpio in Salah Al-Din Governorate

Abstract

This study aimed to identify the presence of Aeromonas hydrophila bacteria in diseased common carp (Cyprinus carpio) fish collected from Salah al-Din Governorate in Iraq. For this purpose, 128 swabs were obtained from skin, gill and fin lesions of 70 fish showing symptoms of hemorrhagic sepsis, skin ulcers and boils, and fin and gill rot. Through different biochemical tests, the isolates showed negative results for Gram stain, methyl red, lactose fermentation, H₂S, and string test, while positive results were recorded for glucose fermentation, oxidase, motility test, catalase, Voges-Proskauer, indole, citrate utilization, and gelatin hydrolysis. Eleven isolates were confirmed as A. hydrophila by amplification of the hemolysin gene fragment (hlyA) by conventional PCR. This study represents the first comprehensive study to characterize A. hydrophila bacteria from infected common carp fish in Salah al-Din Governorate. The findings of this study provide valuable insights for developing genetic diagnostic strategies for A. hydrophila infections in this region.