Revue Méd. Vét., 2012, 163, 10, 486-494 Characteristics of bacteria from the genus Aeromonas The genus Aeromonas belongs to the family Aeromonada- ceae [14]. Its members are Gram-negative nonspore-forming rods, facultative anaerobes, oxidase- and catalase positive, able to reduce nitrates to nitrites and resistant to the vibriostat O/129 (2,4-diamino-6,7-diisopropylpteridine). Motile species possess a single polar flagellum [48]. According to Bergey’s Manual of Systematic Bacteriology [48], the genus Aeromonas includes the following species: Ae- romonas hydrophila, Aeromonas bestiarum, Aeromonas sal- monicida, Aeromonas caviae, Aeromonas media, Aeromonas eucrenophila, Aeromonas sobria, Aeromonas veronii (biovars sobria and veronii), Aeromonas jandaei, Aeromonas schuber- tii, Aeromonas trota, Aeromonas allosaccharophila, Aeromo- nas encheleia, Aeromonas popoffii and two DNA homology groups: Aeromonas spp. (HG11) and Aeromonas spp. (HG13; former Enteric Group 501). During the last decade, several new species are described: Aeromonas culicicola [71], Aero- monas simiae [29], Aeromonas molluscorum [53], Aeromonas bivalvium [52], Aeromonas aquariorum [49], Aeromonas pis- cicola [9], Aeromonas fluvialis [4], Aeromonas taiwanensis and Aeromonas sanarellii [3], Aeromonas rivuli [23].Aeromo- nas spp. are not part of the natural intestinal flora. In the faeces of healthy animals and people, they could be detected only after ingesiton of contaminated food or water [31]. The pathogenicity of aeromonads, as per JANDA and AB- BOTT [35, 36], is due to intracellular structures (pilli, flagella, capsule, lipopolysaccharides, outer membrane proteins) and extracellular products (cytotoxic, cytolytic, haemolytic and enterotoxic proteins). Some fish diseases are caused by Aeromonas spp. members. Mesophilic Aeromonas hydrophila and Aeromonas veronii cause the haemorrhagic septicaemia in carps [38], while Ae- romonas salmonicida induces furunculosis in salmonids [7] Pathogenicity of Aeromonas or- ganisms in humans With regard to the prevalence of disease they cause, JANDA and ABBOTT [34] classify aeromonads into: 1. Aeromonads associated with human disease, based upon clinical frequency rather than disease presentation: - Major pathogens: A. hydrophila (HG 1), A. caviae (HG 4) and A. veronii bt sobria (HG 8). - Minor pathogens: A. veronii bt veronii (HG 10), A. jandaei (HG 9) and A. schubertii (HG 12). SUMMARY Aeromonas spp. is causing a broad spectrum of human and animal illnesses. Aeromonas hydrophila is the agent of haemorrhagic septicaemia in cyprinids, whereas Aeromonas salmonicida – of furunculosis in salmonids. About 85% of gastrointestinal disorders in humans are attributed to Aeromonas hydro- phila, Aeromonas caviae and Aeromonas veronii biovar sobria. Other human pathogens are Aeromonas veronii biovar veronii, Aeromonas jandaei and Ae- romonas schubertii, which are known to cause wound infections, meningitis, osteomyelitis, septic arthritis, endocarditis, peritonitis, urinary tract and ocular infections. Aeromonas spp. is isolated from hydrobionts, meat, meat products, milk, dairy products and vegetables at densities of 10 2 to 10 5 cfu/g. A substantial risk is posed by the ability of microorganisms of genus Aeromonas to grow in foods stored in refrigerator. That is why the research is focused on the in- fluence of temperature, pH, the content of salt, nitrites, phosphates, organic acids and modified atmosphere on their resistance and pathogenicity. Keywords: Aeromonas spp., foods, risk. RÉSUMÉ Prevalence et survie d'Aeromonas spp. dans les aliments – une revue Aeromonas spp. provoquent un large spectre de maladies chez les hommes et les animaux. Aeromonas hydrophila est l'agent de la septicémie haémor- rhagique chez les cyprinidés, tandis que Aeromonas salmonicida – de la fu- runculose des salmonidés. Environ 85 % des troubles gastrointestinaux chez les hommes sont attribués à Aeromonas hydrophila, Aeromonas caviae et à Aeromonas veronii biovar sobria. D'autres agents pathogènes humains sont Aeromonas veronii biovar veronii, Aeromonas jandaei et Aeromonas schu- bertii, qui provoquent des infections de plaies, méningite, ostéomyélite, ar- thrite septique, endocardite, péritonite, des infections urinaires et oculaires. Aeromonas spp. sont isolés de hydrobiontes, viande, produits carnés, lait, produits laitiers et légumes aux 10 2 to 10 5 cfu/g. Un risque particulier est posé par la capacité des Aeromonas de croître dans des aliments conservées dans le réfrigérateur. C'est pourquoi les recherches sont concentrées sur l'in- fluence de la temperatrue, le pH, le contenu de sel, nitrites, phosphates, acides organiques et l'atmosphère modifiée sur leur résistance et pathogénicité. Mots clés : Aeromonas spp., aliments, risque. Prevalence and survival of Aeromonas spp. in foods – a review D. STRATEV*, I. VASHIN AND V. RUSEV Department of Hygiene and Control of Food Products from Animal Origin, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, BULGARIA. *Corresponding author: stratev@mail.bg