Mycoplasmataceae representative Mycoplasma mobile Mycoplasma ikQ bacteria occur

Mycoplasmataceae representative mycoplasma mobile

This preview shows page 295 - 298 out of 594 pages.

Mycoplasmataceae representative Mycoplasma mobile Mycoplasma-\ikQ bacteria occur on fish (Kirchhoff and Rosengarten, 1984), from which infection probably occurs.
Image of page 295
276 Bacterial Fish Pathogens Oxalobacteraceae representative Janthinobacterium lividum Typical and atypical forms of/, lividum are regarded as part of the normal microflora of freshwater (Sneath, 1984) and soil (Moss and Ryall, 1980). Therefore, there would be a ready inoculum of the pathogen in the environment around fish. Pasteurellaceae representative Pasteurella skyensis The source of the pathogen may well have been fish, e.g. mackerel (Birkbeck et al, 2002). Photobacteriaceae representatives Photobacterium damselae subsp. damselae The organism was associated initially with ulcerative lesions along the flank of blacksmith (Chromis punctipinnis), one of the damselfish. These ulcers were noted in Summer and Autumn among fish populations in the coastal waters of southern California. Surveys of wild fish populations led to a conclusion that the ulcers were restricted to species of damselfish. Additional information pointed to a role in human pathogenicity, insofar as the organism has been isolated from human wounds (Love et ai, 1981). Subsequent work demonstrated this organism in sharks (Grimes et ai, 1984a,b; Fujioka et ai, 1988), turbot (Fouz et ai, 1991, 1992), yellowtail (Sakata et al, 1989) and nurse sharks and rainbow trout (in Denmark) (Pedersen et al, 1997a). Ulcerated fish, presumably the result o^ Ph. damselae, accounted for 10-70% of the population in King Harbor, Redondo Beach, California, during August to October, and at a second site (Ship Rock, CataHna Island) during June to October. This suggests a seasonal distribution in the incidence of disease, and possibly coin- cides with warmer water temperatures and lower resistance caused by physiological changes in the host during sexual maturity. Conceivably, Ph. damselae occurs nor- mally in the marine environment, where it could pose a constant threat to susceptible fish species. Indeed, seawater is the likely mode of transmission of virulent cells of the pathogen, with cells adhering to and resisting the bacteriocidal effects of mucus. This suggests that skin is a site of entry into the host (Fouz et al., 2000). Photobacterium damselae subsp. piscicida There is no doubt that pasteurellosis is a serious condition of both farmed and wild fish populations (Snieszko et al., 1964a; Kusuda and Yamaoka, 1972; Ohnishi et al., 1982; Yasunaga et al., 1983). Heavy mortalities, in the range of 40-50% of the stock, have occurred during Summer months. Unfortunately, the reasons for these out- breaks are largely unknown. Likewise, the precise nature of the pathogenicity mechanism remains to be elucidated.
Image of page 296
Epizootiology: Gram-negative bacteria 277 It is thought that infection takes place in seawater at temperatures of approxi- mately 25°C (Yasunaga et ai, 1983). Toranzo et al. (1982) devised a series of survival experiments, and concluded that Ph. damselae subsp. piscicida was short-lived in freshwater and estuarine conditions. Thus, in freshwater the organism could not be cultured after 48 h at 20°C. Survival in estuarine water (salinity = 12%o) was
Image of page 297
Image of page 298

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