Prevalence and resistance to antibiotics for Aeromonas species isolated from retail fish in Turkey

Mesophilic aeromonads are among the most common bacteria in water habitats throughout the world, and these bacteria frequently cause disease in fishes. They are also causative agents of acute diarrheal disease in man following ingestion water. In this study, a total of 132 market fish (64 freshwater and 68 seawater) samples representing were collected in Ankara (Turkey) and investigated for the presence of Aeromonas spp. They were isolated from 106 (80.3%) out of the 132 fish samples tested. The distribution of Aeromonas spp. varied depending on the samples (gill, intestine, liver kidney) examined. In freshwater samples, the predominant species was A. caviae (66.0%), followed by A. hydrophila (22.6%) and A. veroni bv. sobria (11.6%). In seawater samples, the predominant species was,found A. veroni bv. sobria (41.5%), followed by A. hydrophila (30.1%) and A. caviae (28.3%). The 132 isolated Aeromonas spp. strains were further examined for hemolytic, lipolytic and proteolytic activity. Of the present isolates, more than 80% (A. veroni bv. sobria, A. hydrophila) were positive for hemolysin activities. Lipolytic and proteolytic activity of identified strains were found in more lower incidence. All aeromonads (A. hydrophila, A. veroni bv. sobria, A. caviae) strains showed resistance to ampicillin, cephalothin and trimethoprim. The least resistance was found for chloramphenicol (9.0%). In contrast, all the strains were susceptible to ciprofloxacin and ceftriaxone. In Turkey, there have been few studies on Aeromonas and its virulence factors. This study therefore highlights an important incidence of Aeromonas spp., with virulence and antibiotic resistance, isolated from fish intended for human consumption in Turkey.