Pathogenic Activities of Aeromonas hydrophila biovar hydrophila (Chester) POPOFF and VERON, 1976 to Fishes

Abstract

A total 291 strains of motile members of the genus Aeromonas were classified according to the taxonomic scheme proposed by POPOFF and VERON (1976). Forty three were indetified as A. hydrophila biovar hydrophila, 9 as A. hydrophila biovar anaerogenes, and 52 as A. sobria. The remaining 187 strains could not be identified. Thirty seven (86%) of 43 A. hydrophila biovar hydrophila, 3 (33 %) of 9 A. hydrophila biovar anaerogenes, 32 (62 %) of 52 A. sobria, and 65 (35%) of the 187 unidentified originated from fishes. All 6 A. hydrophila biovar hydrophila examined fell in the category of high virulence. The Japanese loach injected with them were killed earlier than those injected with the other motile Aeromonas, and the difference of mean time to death was statistically significant (P <0.01). The difference of average value of proteolytic activity of the broth culture filtrate between A. hydrophila biovar hydrophila and the other was significant (P <0.01), also. Exophthalumus and scale protru sion were evident only among fish injected with the sonicated cell extracts of A. hydrophila biovar hydrophila.

Extracellular proteolytic activity of Aeromonas hydrophila complex.

“…Recent studies (WAKABAYASHI et al, 1981;HSU et al, 1981) have demonstrated that the proteolytic activity of elastase and caseinase are associated with the virulence of A. hydrophila complex strains. Several extensive reports dealing with Pseudomonas aeruginosa indicate that these proteases could also be virulence factors of that organism (HOLDER and HAIDARIS, 1979;JANDA and BOTTONE, 1981;PAVLOVSKIS and WRETLIND, 1979;SNELL et al, 1978).…”

The expression of proteinases and haemolysins byAeromonas hydrophilaunder modified atmospheres

“…However, strain diversity within Aer. hydrophila is well known ( Wakabayashi et al . 1981 ; Nieto and Ellis 1991).…”

“…However, strain diversity within Aer. hydrophila is well known (Wakabayashi et al 1981;Nieto and Ellis 1991). This diversity has previously been used to explain the differences in genotypic and phenotypic characteristics observed in Aer.…”

Multiplex nested-polymerase chain reaction for the simultaneous detection ofAeromonas hydrophila, Edwardsiella tarda, Photobacterium damselaeandStreptococcus iniae, four important fish pathogens in subtropical Asia

“…Aeromonas hydrophila , an aetiological agent of fish diseases, is considered to be a primary and secondary pathogen resulting in haemorrhagic septicaemia in fish (Lu 1992). It is found usually in freshwater fish species (Wakabayashi, Kanai, Hsu & Egusa 1981) but occasionally in marine fish (Kaper, Lockman, Colwell & Joseph 1981). Edwardsiella tarda causes the serious systemic disease, commonly known as Edwardsiella septicaemia or edwardsiellosis which occurred in cultured Japanese eels ( Anguilla japonica ) in Japan, China and Taiwan (Egusa 1976; Liu & Tsai 1980).…”