E. coli  General Notes

 

Name

Escherichia coli

Agent

Bacteria belonging to the Enterobacteriacae. 

Other members include salmonella and klebsiella

Diseases

0-3 days of age associated with toxins

Sudden death, often with few clinical signs.  Those that survive can be very stunted with a gaunt hair staring coat.   Reddening of the skin of the perianal area and under-side of tail may be present.

Pre-weaning scour 3 to 10 days of age

Loose to watery  brown, white or cream coloured diarrhoea.  Reduced gain and loss of weight, depression and loss of appetite, rough hair coat, sunken eyes, unthrifty appearance with ribs and backbone highly visible.  One or two days of scours pre-weaning can add 5 days to finishing.

Post-weaning diarrhoea 1 - 10 days post-weaning

Loose to watery  brown, white or cream coloured diarrhoea.  Reduced gain and loss of weight, depression and loss of appetite, rough hair coat, sunken eyes, red streaking or soreness in the anal region, unthrifty appearance with ribs and backbone highly visible.  One or two days of diarrhoea post-weaning can add 5 days to finishing.

Bowel oedema

Toxins from E. coli in the stomach and intestines in the post-weaning period result in oedema throughout the animal which presents with swollen eyelids and death and ill thrift.  Some neurological signs can be seen.  Presenting signs seen most commonly second week after weaning.

Mastitis

Immediately after farrowing, reddening hard and hot mammary gland.  Most E. coli mastitis are actually from toxins from the intestines rather than mammary gland. Toxin works against the Prolactin hormone

Cystitis and some involvement in pyelonephritis

Many sows have cystitis after farrowing or service associated with poor urination or hygiene.  If the infection is complicated with other bacteria, such as Actinobaculum suis from the boar's prepuce, the kidneys can become infected as well (pyelonephritis).

The organism

The bacteria is the large oval in the centre.  Surrounding the bacteria are 'hairs' called fimbriae which contain the adhesion factors which the bacteria use to stick to the host cells.  Flagellae are long and used to move the bacteria.  The example shown has no flagella.

Classification

By cell wall

O antigens O147 for instance

Fimbriae

F antigens (use to be K antigens) F1, F4 (K88), F5(K99), F18 (F107),

F6 (987P), F41, FP

Flagellae

H antigens (not used to classify E. coli)

Therefore the E. coli can be given a code which is useful to indicate its likely role in the disease. 

For instance  Diarrhoea is often associated with O147, F4, F5  this is E. coli Abbotstown

Bowel Oedema is associated with F18 fimbriae.


 

Recognising the code is important in the selection of the correct vaccine

Toxins

E. coli can produce a number of toxins

Exotoxins

LT and ST toxins are actively produced by some strains.  These are important in causing scour. Shigela-like toxin type II variant (SLT-IIe), Stx2e, verotoxin oedema disease principle act on the wall of the small arteries resulting in oedema.  Enteroaggregative (EAST1) toxin.

Endotoxins

From breakdown products from the cell wall which plays a role in mastitis as it acts against Prolactin (the hormone which releases milk) and in urinary tract diseases.  Major cell wall toxin called Lipid A.

Diagnosis

Laboratory cultures.  The collection of the sample is critical and requires a rectal swab from a recently infected (ideally untreated piglet) or if the problem is severe the submission of live recently ill pigs provides the best material.

Checking for and ruling out viral or parasitic causes

Examine intestinal pH, when at 8 or above suggestive of E. coli

Check herd history, past treatments, feed medication, incidence of scour

Determine age of affected pigs, disinfectants used, pig flow and environmental effects

Treatment and control

Hygiene

Adequate pressure washing.  Utilise All-in/All-out.  Sick animals are not put back through the system.

Pre-weaning scour

Check for draughts and colostrum intake.

Post-weaning scour

Check mixing routines, draughts and temperature variations/cooling curves.

Antibiotics

Ideally after the organism has been grown in the lab.    The E. coli is grown and then tested against a range of antibiotics to determine which will provide the best cure

Vaccines

To the sow and via colostrum to the piglet.  Note vaccine storage and administration have got to follow prescribed protocols.  Water vaccines are available for bowel oedema

Farming Practices

To reduce stressors on the pig, particularly in neonate.  Many cases of 'scour' associated with E. coli will respond poorly to antibiotics as the real cause are draughts.  Examine each area in detail and remove as many of the stress factors as possible.  Even a barely perceptible draught can result in a wind chill 3•C below thermometer readings.  A draught can be considered to be a chilling “wind” of only 0.2 m/s  Environmental examination

Colostrum

The vital ingredient to survival pre-weaning.  Feed back of weaner faeces is given to sows and gilts to ensure that her colostrum is adequate

Feeding routines

Ensure good quality feed is being used as creep.  Check feed quality actually being fed not just in the bag.  Check feed for allergic factors, i.e. plant proteins being fed too early.   In pre- and post-weaners provide small amounts of fresh feed several times a day, this helps to minimise digestive stress

Dry sow feeding

Effective and disciplined feeding regimes are required to reduce udder oedema, mastitis and constipation

Adequate Water

The lack of water is a major stress factor on the pig at all ages.  However, insufficient marginal water supplies play a major role in the cause of cystitis and kidney disease in the pig

Genetics

With bowel oedema in particular, only pigs which have the correct genes to allow the F18 fimbriae to attach will result in the disease. Changing the genetics may result in removal of the disease from the farm.  There are F4 negative pigs, but these have not been exploited commercially.  F18 negative pigs are commercially available.

Do not select from sows/gilts who have any history of diarrhoea in the farrowing house.  Over time this will select away from susceptibility towards E. coli types especially F4.

Zoonotic implications

E. coli is a potential pathogen in humans.  However, the more significant strain

E. coli VTEC 0157 is only very rarely found – less than 0.3% of carcases in a UK study.