Strains of Vibrio vuln~flcus biotype 2 were recovered from diseased European eels Angujlla anguilla during 2 epizootics These stralns were biochemically and serologically identical to the ATCC 33149 strain, which was lsolated from the Japanese eel Angujlla japonica. The isolates of biotype 2 from European eels were more virulent for elvers (LD50 < 10' cfu) than the Japanese strain used as control (LDS0 = 104 cfu). All strains of biotype 2 were able to adhere to human and fish cell lines and were also strongly cytotoxic. The extracellu1a1-products (ECPs) of the Japanese strain exhibited lipolytic, phospholipolytic, proteolytic, and haernolyt~c activities, whereas the ECPs of the Spanish isolates displayed only proteolytic activity. Strains of biotype 1 were recovered from tank water and healthy eels during the second outbreak. These isolates were biochemically similar to the type strain ATCC 27562, and serologically distinct from the isolates of biotype 2. Strains of biotype 1 produced proteases, haemolysins, and cytotoxins and showed specific adhesion to human cells, but they were non-pathogenic for eels. The strains of biotype 2 were more virulent for mice (LDS" = 10' to 106cfu) than the strains of biotype 1 (LDS(, = 10%fu), suggesting that this eel pathogen may also represent a health hazard problem for fish farmers.

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Vibrio vulnificus biotype 2 is classically considered an obligate eel pathogen. However, it has recently been associated with one human septicemic case. In this paper, the opportunistic behavior of this pathogen is discussed. The bacterium can survive alone in brackish water or attached to eel surfaces for at least 14 days. It is able to spread through water and infect healthy eels by using skin as a portal of entry. These results suggest that water and infected eels may act as reservoirs of infection. A capsule seems to be essential for waterborne infectivity, which would explain why cells recovered from naturally diseased eels give rise to pure cultures of opaque colonies. The spread of the disease is dependent on temperature and water salinity, thus suggesting a method to reduce the risk of epizootics and that of infection for humans.

Phenotypic and genetic studies were performed on some atypical aeromonas strains of uncertain taxonomic position. 16S rRNA gene sequence analysis revealed that these strains represent a hitherto unknown genetic line within the genus Aeromonas, for which the name Aeromonas allosaccharophila sp. nov. is proposed. The type strain is CECT 4199.

Aims:  To determine the incidence of multiple antibiotic‐resistant strains of the emergent human pathogens Legionella pneumophila, Pseudomonas aeruginosa and mesophilic Aeromonas species among those isolated from water reservoirs and industrial cooling systems. Methods and Results:  Water from four natural water reservoirs and four industrial cooling towers was sampled for 1 year period. The total heterotrophs, mesophilic Aeromonas, Pseudomonas spp. and Legionella spp. counts were performed as recommended by standard procedures, and the sensitivity of the isolates to 27 antibiotics was tested. A total of 117 Aeromonas, 60 P. aeruginosa and 15 L. pneumophila strains were isolated and identified by means of biochemical tests and DNA probes. 46·4% of Aeromonas, and 100% of P. aeruginosa isolates presented multiple resistance. Legionella pneumophila strains were generally sensitive to the drugs used. Conclusions:  Antibiotic‐resistant pathogenic bacteria belonging to P. aeruginosa and mesophilic Aeromonas species are common in natural aquatic environments. Thus, the risk of waterborne diseases owing to domestic and industrial uses of freshwater should be re‐examined from the increase of bacterial resistance point of view. Significance and Impact of the Study:  These data confirm the emergence of bacteria resistant to antibiotics in aquatic environments.