serological and genotypic heterogeneity within the descriptions of fish

Serological and genotypic heterogeneity within the

This preview shows page 106 - 108 out of 594 pages.

serological and genotypic heterogeneity within the descriptions of fish-pathogenic Aer. hydrophila (Maclnnes et al, 1979; Leblanc et al, 1981; Allen et al, 1983a). Aeromonas hydrophila The fish pathogens comprise Gram-negative, straight, chemo-organotrophic (fer- mentative) rods of approximately 0.8-1.0 x 1.0-3.5 jim in size, which are motile by single polar flagella. Arginine dihydrolase, catalase, P-galactosidase, indole, lysine decarboxylase (a variable response may occur), cytochrome-oxidase and phospha- tase are produced, but not H2S, ornithine decarboxylase, phenylalanine or tryp- tophan deaminase. Nitrates are reduced to nitrates without the production of gas. The Voges Proskauer reaction is positive, but not so the methyl red test. Growth occurs in 0-4% (w/v) but not 5% (w/v) sodium chloride, at 5-37°C and in potassium cyanide. Aesculin, blood (P-haemolysis; by some isolates), casein, DNA, gelatin, lecithin, RNA, starch and Tween 80 are degraded, but not pectin or urea. There is resistance to the vibriostatic agent 0/129. A^-acetyl-P-D-galactos- amine, L-alanine, L-arabinose, /7-arbutin, DL-lactate, D-mannitol, putrescine, D-serine, salicin and D-sucrose are utilised as the source carbon course for energy and growth, but not D-cellobiose, DL-isocitrate, P-alanine, 4-aminobutyrate or urocanic acid. Sodium citrate is utilised by some isolates. Acid is produced from cellobiose (a variable response), fructose, galactose, glucose (acid and gas), glycerol (a variable response), lactose (a variable response), maltose, mannitol, salicin, sucrose and trehalose, but not from adonitol, dulcitol, erythritol, inositol, raffinose, rhamnose, sorbitol or xylose (Paterson, 1974; Larsen and Jensen, 1977; Allen et al., 1983a; Popoff', 1984). The G + C ratio of the DNA falls in the range of 58-61.6 mol % (Larsen and Jensen, 1977; Maclnnes et al., 1979; Huys et al., 2002).
Image of page 106
84 Bacterial Fish Pathogens In contrast to the usual characteristics of Aer. salmonicida, the majority of isolates of Aer. hydrophila are capable of growth at 37°C and are, indeed, motile. Some isolates have also been determined to produce diffusible brown pigments, as does Aer. salmonicida, which could superficially confuse diagnosticians (Ross, 1962; Paterson, 1974, Allen et al, 1983a, b; Austin et al, 1989). Santos et al (1991) serotyped 62 motile Aeromonas spp. from rainbow trout. Of these, 55 isolates (89% of the total) were distributed between 17 serogroups, of which 03, 06, Oil and 019 were dominant. Moreover, 40 (63% of the total) of these isolates were pathogenic to fish. Nevertheless, antigenic cross-reactivity with Aer. salmonicida and Aer. sobria has been noted (Leblanc et al., 1981). However, Shaw and Hodder (1978) reported that the core region of the LPS of Aer. hydrophila was distinct from that of Aer. caviae and Aer. sobria. Aeromonas jandaei Aer.jandaei has been reported as pathogenic to eel in Spain (Esteve et al, 1993, 1994; Esteve, 1995). Initially, eight isolates were recovered using unstated procedures during 1987 and 1988. Whereas initially the method of identification was not stated (Esteve et al., 1994), a subsequent numerical taxonomy study equated isolates with Aer. jandaei (EstQYQ, 1995).
Image of page 107
Image of page 108

You've reached the end of your free preview.

Want to read all 594 pages?

  • Spring '20
  • Bacteria, representative, gram-negative bacteria

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes
A+ icon
Ask Expert Tutors