''Photobacterium damselae'' subsp. ''piscicida'' (previously known as ''Pasteurella piscicida'') is a

gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...

rod-shaped

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were amon ...

that causes disease in

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

Hosts

Hosts of ''Photobacterium damselae'' subsp. '' iscicida'' include: * Barramundi/Asian sea bass (''

Lates calcarifer The barramundi (''Lates calcarifer'') or Asian sea bass, is a species of catadromous fish in the family Latidae of the order Perciformes. The species is widely distributed in the Indo-West Pacific, spanning the waters of the Middle East, Sout ...

'')Trung Hieu Pham, Shreesha Rao, Ta-Chih Cheng, Pei-Chi Wang, Shih-Chu Chen, The moonlighting protein fructose 1,6-bisphosphate aldolase as a potential vaccine candidate against Photobacterium damselae subsp. piscicida in Asian sea bass (Lates calcarifer), Developmental & Comparative Immunology,Volume 124,2021,104187,ISSN 0145-305X,https://doi.org/10.1016/j.dci.2021.104187.

Disease

Pasteurellosis Pasteurellosis is an infection with a species of the bacterial genus ''Pasteurella'', which is found in humans and other animals. ''Pasteurella multocida'' (subspecies ''P. m. septica'' and ''P. m. multocida'') is carried in the mouth and respir ...

is also described as photobacteriosis (due to the change in the taxonomic position), caused by this

halophilic The halophiles, named after the Greek word for "salt-loving", are extremophiles that thrive in high salt concentrations. While most halophiles are classified into the domain Archaea, there are also bacterial halophiles and some eukaryotic species, ...

bacterium. It was first isolated in mortalities occurring in natural populations of

white perch The white perch (''Morone americana'') is not a true perch but is a fish of the temperate bass family, Moronidae, notable as a food and game fish in eastern North America. In some places it is referred to as "Silver Bass". The name "White per ...

(''Morone americana'') and striped bass (''M. saxatilis'') in 1963 in

Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...

, USA (''Snieszko ''et al.'', 1964''). Since 1969, this disease has been one of the most important in Japan, affecting mainly yellowtail (''

Seriola quinqueradiata The Japanese amberjack or yellowtail, ''Seriola quinqueradiata'', is a species of jack fish in the family Carangidae. It is native to the northwest Pacific Ocean, ranging from China (called ), Korea (called ), and Japan to Hawaii. It is greatl ...

'') (Kusuda & Yamaoka, 1972). From 1990 it has caused economic losses in different European countries including France (Baudin-Laurencin ''et al.'', 1991), Italy (Ceschia ''et al.'', 1991), Spain (Toranzo ''et al.'', 1991), Greece (Bakopoulos ''et al.'', 1995), Turkey (Canand ''et al.'', 1996), Portugal (Baptista ''et al.'', 1996) and Malta (Bakopoulos ''et al.'', 1997). Gilthead sea bream ('' Sparus aurata''), seabass (''

Dicentrarchus labrax The European bass (''Dicentrarchus labrax'') is a primarily ocean-going fish native to the waters off Europe's western and southern and Africa's northern coasts, though it can also be found in shallow coastal waters and river mouths during the su ...

'') and sole ('' Solea'' spp.) are the most affected species in Europe Mediterranean countries, as well as

hybrid striped bass A hybrid striped bass, also known as a wiper or whiterock bass, is a hybrid between the striped bass (''Morone saxatilis'') and the white bass (''M. chrysops''). It can be distinguished from the striped bass by broken rather than solid horizont ...

(''M. saxatilis'' x ''M. chrysops'') in the USA. However, the natural hosts of the pathogen are a wide variety of marine fish (Romalde & Magariños, 1997). This pathology is temperature dependent and occurs usually when water temperatures rise above 18-20 °C. Below this temperature, fish can harbour the pathogen as subclinical infection and become carriers for long time periods (Romalde, 2002).

Symptoms

Pastereullosis is also known as pseudotubercullosis because it is characterized by the presence, in the chronic form of the disease, of creamy-white granulomatous nodules or whitish

tubercule In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projection, ...

s in several internal organs, composed of masses of bacterial cells,

epithelial Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercell ...

cells, and fibroblasts. The nodules are most prominent in internal viscera, particularly kidney and spleen, and the infection is accompanied by widespread internal necrosis (Evelyn, 1996; Romalde, 2002; Barnes ''et al.'', 2005).

Anorexia Anorexia nervosa, often referred to simply as anorexia, is an eating disorder characterized by low weight, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thin. ''Anorexia'' is a term of Gre ...

with darkening of the skin as well as focused necrosis of the gills are the only external clinical signs often observed. These lesions are generally missing in the acute form. The disease is difficult to eradicate with antibiotic treatments, and there is evidence that carriers under stressful conditions could suffer from reinfection (Le Breton, 1999).

Identification

Morphologically, the bacteria is a rod shaped cell, with no

motility Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ...

Gram negative The gram (originally gramme; SI unit symbol g) is a unit of mass in the International System of Units (SI) equal to one one thousandth of a kilogram. Originally defined as of 1795 as "the absolute weight of a volume of pure water equal to th ...

, with bipolar staining. The presumptive identification of the pathogen is based on standard biochemical tests. In addition, although ''Ph. damselae'' subsp. ''piscicida'' is not included in the API-20E code index, this miniaturised system can also be useful for its identification, since all strains display the same profile (2005004). Slide agglutination testing using specific antiserum is needed for a confirmative identification of the microorganism (Romalde, 2002).

Virulence

The virulence of the pathogen implies the production of polysaccharide capsular layer, and extracellular products, and is also depending on iron availability (Lopez-Doriga ''et al.'', 2000). The bacteria spreads via infected

phagocyte Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells. Their name comes from the Greek ', "to eat" or "devour", and "-cyte", the suffix in biology denoting "cell", from the Greek ...

s, mainly macrophages. This spread can be rapid, and lethal effects may occur within a few days of challenge, affecting tissues containing large numbers of the pathogens (Evelyn, 1996).

References

External links

* Type strain of ''Photobacterium damselae subsp. piscicida'' at Bac''Dive'' - the Bacterial Diversity Metadatabase] *Necrotizing fasciitis due to ''Photobacterium damsela'' in a man lashed by a stingray. Barber GR, Swygert JS. New England Journal of Medicine. 2000 342:824 etter {{Taxonbar, from=Q7187713 Vibrionales Bacterial diseases of fish Subspecies