Pseudomonas spp.

Pseudomonas is a Gram-negative aerobic rod. Pseudomonas species measure 0.5 to 0.8, µm by 1.5 to 3.0 µm. They move by a single polar flagellum. It has a wide a diverse habitat, growing well in water and lives in soil, ponds, sinks and fresh vegetables.

Pseudomonas

Pseudomonas is a type of bacteria that have adapted to the hostile environment of the host's tissue (antibodies, phagocytes) and exposed surfaces (heat, cold, shear forces) by forming colonies that generate a kind of exterior shell composed of a collectively produced extracellular matrix of carbohydrate exopolysaccharide. A large collection of these groups of bacterial cells adhering to a surface is called a bacterial biofilm. This creates a problem for identifying and treating these type of bacteria because bacteria grown in culture in the laboratory for identification purposes may be a thousand times less resistant to a medication than the same bacteria inhabiting the fish's tissue.

Pseudomonas was once a very difficult bacterial disease to combat, resistant to penicillin and a battery of other antibiotics, until the development of the fluoroquinolone class of antibiotics. Bayer Baytril is the best known type of this antibiotic.

The bacteria are present in most natural waters and infect most species of fish. Pseudomonas usually makes its appearance when water conditions deteriorate. It is very opportunistic bacteria, almost never a problem with healthy fish, and quickly appearing when tank conditions deteriorate.

Pseudomonads require water, oxygen and nearly any carbon source for growth. It producees during growth two pigments: blue-green pyocyanins and fluorescein. The later pigment appears yellow under ultraviolet light. In infections, blue or green pus may be produced but most green pus is not due to pseudomonas. The silvery oily sheen seen on the surface of stagnant water is due to pseudomonas.

In humans infections caused by Pseudomonas species include endocarditis, pneumonia, and infections of the urinary tract, central nervous system, wounds, eyes, ears, skin, and musculoskeletal system.

Symptoms and Behavioral Signs
Pseudomonas have been credited with causing pseudomonad septicemia, red spot disease, fin/tail rot, and others.

Redness in areas of the body or ulcers are indications of bacterial infections. Other indications:

•    fish become shy and hide
•    mouth, fins erode or rot
•    holes appear in the skin
•    red areas on the body, especially in vent area

Causative Conditions
Stress, rupture of the skin, and penetration of body tissues by parasites are the leading causes of bacterial infections. Stress can be caused by crowding or adverse water conditions, which lead to a lowering of the immune system. Crowding usually makes the spread of the disease easier.

Poor nutrition leads to a lowering of the immunity system and subsequent infection. Dry foods quickly lose their vital vitamin potency.

Bacterial infections are often secondary to other types of infections, such as fluke infections. The flukes' hooks cause ruptures in the skin and often are carriers of bacteria.

Diagnosis
Laboratory cultures of bacteria are practically the only method of identifying bacteria. However this method is costly and impractical for the average aquarist.

Prevention and Treatment
Bacterial infections are often secondary to other types of infections, such as fluke infestations, so a treatment program may have to first remove the primary cause of the infection.

Reducing the bacterial load of the tank through regular cleaning of filter media, good nutrition, warmth and regular water changes (30% a week) are primary methods of avoiding bacterial infection. If the fish in the tank have been overfed, reducing the organic pollutants with potassium permanganate is a good prophylactic. PP will also remove the slime coat the fish, along with its parasites. A treatment with another medication can than follow.

According to the Massachusetts Office of Coastal Zone Management, terramycin can be used to control Pseudomonas. The dosage regimen is 2.5 to 3.75 g/100 lb/day for ten days.

There are a number of other antibiotics offered at the local fish store. Unfortunately most of them do not work because of their overuse and the development of drug-resistant strains of bacteria.

See the entry for Baytril. Baytril is especially effective against pseudomonas. However, there is a lot of anecdotal evidence that it is gradually losing its efficacy.

The guppy breeder should regard the role of antibiotics as reducing the bacterial load to the point where the guppy's natural immune system can take over. Antibiotics rarely eradicate the bacteria from the aquarium. For this reason, correcting the causative condition and doing a large water change (40%) on three subsequent days may be as effective as an antibiotic for fish that are mildly infected. However this approach should only be used if the fresh water has exactly the same parameters as the existing water. Fish should not be stressed.

Guppies can be bathed in antimicrobial agents like Trimethoprim Sulfa or Potassium Permanganate.

Treating internal diseases with antibiotics is more effect through bioencapsulation. However, beneficial bacteria are destroyed, making the use of vitamin supplements during treatment mandatory.