Virulence and antibiotic susceptibility of Aeromonas spp. isolated from Nile tilapia fish, fish ponds and river water in Sharkia Governorate, Egypt

Abstract EN

Aeromonas isolates from Nile tilapia fish, fish ponds and River water were investigated for their ability to produce different potential virulence factors i.e.

hemolysins, proteases, lipases, Gelatinases.

In addition, the susceptibility to antibiotics of Aeromonas isolates was examined.

A total of 376 Aeromonas spp.

were identified on the basis of biochemical tests and six of them were confirmed by sequencing of 16S rDNA gene as (A.

caviae, A.

encheleia, A.

molluscorum, A.

salmonicida, A.

veronii and A.

veronii bv.

veronii).

The antibiotic resistance testing revealed that all of the Aeromonas strains were resistant to β–lactam (amoxicillin/clavulanic acid) antibiotics.

However, the resistance to other antibiotics was variable.

All Aeromonas strains were found to be resistant to ampicillin, cephalexin, cephradine, rifampin as well as to cephalothin.

The majority of the Aeromonas strains either isolated from fish or water were capable to produce hemolysins (92.8%), lipases (88.4%), proteases (92.5%) and gelatinases (90.6%) as the virulence factors.