Escherichia coli (E. coli)

Description

Escherichia coli - commonly referred to as E. coli, this Gram-negative bacterium is a member of the Enterobacteriacae species. While many harmless or beneficial strains of E. coli occur widely in nature, including the intestinal tracts of humans and other vertebrates, birds and reptiles pathogenic types are a frequent cause of both enteric and urogenital tract infections. Several different types of pathogenic E. coli are capable of causing disease. A particularly dangerous type is referred to as enterohemorrhagic E. coli, or EHEC. The first such strain was identified in the United States in 1982. Since then, EHEC strains have been associated with food-borne outbreaks traced to undercooked hamburgers, unpasteurized apple juice or cider, salad, salami, and unpasteurized milk. EHEC strains produce toxins that have effects similar to those produced by bacteria of the Shigella genus. These enterotoxins can damage the lining of the intestine, cause anemia, stomach cramps and bloody diarrhea, and hemolytic uremic syndrome (HUS) leading to kidney failure. In North America, HUS is the most common cause of acute kidney failure in children.

In Birds

Birds, especially psittacines, are less dependent on E. coli and rely on a more Gram-positive gut flora. However, softbills such as the passerines (finches, jays, songbirds), columbiforms (pigeons and doves), galliforms (chicken-like birds), raptors (hawks, falcons, owls), and ratites (emus and ostriches), have a high incidence of normal Gram-negative gut flora of many varieties including E. coli. The distribution of E. coli in psittacines varies one one species to another. It is less common in Amazons and macaws, sometimes found in greys, and common in cockatoos and Eclectus. In fact, E. coli can compose as much as 30 percent of the gut flora of some psittacines and others like cockatiels and budgies carry somewhat less.

Transmission:

The bacteria is shed from an infected bird in the fecal material as well as nasal and or ocular secretions. The organism remains stable outside the host body and may dry as a dusty substance. This dust contaminates the air in the form of aerosols. These aerosols are then inhaled by another possible host. Susceptibility as well as the amount of contamination determine whether or not the new host becomes infected with the disease. Other forms of transmission include infected hens feeding their young with contaminated crop contents, as well as contaminated feed and drinking water. Vertical transmission (transmission of the bacteria to and egg) can occur, subsequently chicks hatch and spread salmonella by direct contact. The embryo may die if bacteria levels become to high.The disease has a greater chance of spreading in overcrowded conditions, stale air environments, nest-boxes, and brooders. Pet shops, bird marts, and quarantine stations are also high risk areas.

Symptoms:

Ruffled feathers - diarrhea - listlessness - weakness - shivering - vent picking The severity of the illness can depend on the age of the bird, the virulence of the bacteria, the immune system, stress and the degree of contamination. Affected birds can also become carriers showing no disease symptoms. These carriers can spread the disease to their offspring and may later become ill as a result of stress. Baby birds, with less developed immune systems, are more susceptible to disease and frequently die. Chronic infections in adult birds may form abscesses, fail to hatch eggs, have changes in eating habits and may intermittently pass contaminating bacteria.

Prevention:

Keep water and feed bowls free of fecal material. Identify carrier birds and properly treat them. Careful disposal of contaminated materials. Minimize Stress in the aviary. People working with contaminated material should practice good hygiene.

Treatment:

Broad spectrum antibiotics should only be started when a sample for culturing has been taken. Oral and injected antibiotics should be given simultaneously in severe cases. The sulfa drugs are good to use orally. Kanamycin and Gentamycin are usually effective by injection. When Gentamycin is used do not allow dehydration. Dehydration may cause toxicity to occur. If necessary, the antibiotics can be changed after sensitivity results are known.If diarrhea is severe Kaopectate or Pepto Bismal may be given orally with 2 to 3 drops in mouth three times per day. Water consumption should be monitored to prevent dehydration. Maintain a stress free environment. An incubator or a heating pad under the cage should be used to maintain the temperature between 85 and 90 degrees. Lacking an incubator if the heating pad alone won't maintain the temperature, place the cage in a box and the box on the heating pad with a thermometer in the back of the box in order to monitor temperature.ANTIBIOTICS: Kanamycin: Dosage: .01 mgl to one gram of body weight intramuscularly twice daily. Gentamycin: Dosage: .01 mg to one gram of body weight intramuscularly once daily or 25 mg. to 120 ml of drinking water orally. Trimethoprim/Sulfamethoxazole Suspension: Dosage .002 ml to one gram of body weight orally twice daily. Sodium Sulfachiorpridazine Powder: Dosage ¼ tsp to 120 ml drinking water ANTIDIARRHEALS: Pepto Bismol: Coats the intestinal tract. Helps to form a firmer stool. Dosage 2-3 drops in the mouth, 3 times daily. Kaopectate: Daolin and pectin coat the intestinal tract and form a firmer stool. Dosage 3 drops in the mouth 3 times daily. *Please check with the manufacturer of the specific antibiotic for additional information before treatment is started. Allays consult with your local avian veterinarian for additional information before treating individuals.

Diagnosis:

For best cultures are taken directly from the cloaca rather than from a fecal sample. If the bird dies, intestinal material, liver, blood and spleen can also be cultured. Anytime E. coli is found in an internal culture other than the gastrointestinal tract, it should be considered pathogenic. E. coli can proliferate uncontrollably outside its normal home in the gut. However, some strains of E. coli can cause gastrointestinal disease. So, even in the gut, the bacterium may be pathogenic.Sensitivity testing should be performed since enteric bacteria are often resistant to several antibiotics.

Sample:

E. coli is usually detected from a cloacal (vent) culture. It is best to take the culture directly from the cloaca rather than from a fecal sample. A fecal sample may be contaminated by another bird or animal, such as a rodent.

Handling:

Prior to shipping samples should be stored at 4 C. Samples must be shipped overnight in a transport medium.