Motile aeromonads recovered from tilapia (Oreochromis niloticus) cultured in earthen ponds in the Philippines: assessment of antibiotic susceptibility and multidrug resistance to selected antibiotics

A total of 177 motile Aeromonas spp., comprised A. hydrophila (n=162) and sobria (n=15), isolated from the water, sediment, gills intestines tilapia collected grow-out culture earthen ponds in Philippines were investigated for their antimicrobial susceptibility to 10 antibiotics commonly used fish aquaculture. All spp. tested generally exhibited a very high percentage resistance amoxicillin (A. hydrophila: 95%; sobria: 100%), erythromycin (99%;100%), neomycin (83%;100%), oxytetracycline (92%;100%), respectively. On contrary, they showed substantial chloramphenicol, nitrofurantoin, doxycycline, enrofloxacin norfloxacin. Results testing demonstrated that 94.4% 100% isolates resistant belonging at least 3 or more categories therefore considered as multiple drug strains. The antibiotic (MAR) indexing strains originated high-risk sources.