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E. coli infection in pigs, causes and corrective action

Colibacillosis, or E. coli infection, is one of the major diseases for swine industry which is a typical bacterial disease caused by pathogenic Escherichia coli (E. coli). It mostly causes illness and death in neonatal and recently weaned pigs. With the increasing incidence region, incidence rate and mortality rate, colibacillosis became a new background frequent and frequently-occurring disease.

The damage caused in the economy and animal sanity by the porcine colibacillosis are significant. Post-weaning diarrhea (PWD) which is commonly associated with enterotoxigennic E. coli (ETEC), is one of the most prevalent porcine diseases, accounting for substantial economic losses worldwide (Han et al, 2007; Cheng et al, 2006).

Types of colibacillosis

Colibacillosis occur at five main types (Straw et al, 2006)

Type of colibacillosisTiming
Neonatal diarrheaFirst 4 days after farrowing
Pre-weaning piglet diarrheaFirst week post-farrowing to weaning
Post-weaning diarrhea  First few days after weaning
Edema diseaseTypically after weaning

Other E. coli infections

such as E. coli mastitis, urinary tract infection, septicemia and so on)


Neonatal diarrhea

Feces may be clear or white/yellow/brown. Diarrhea will appear 2-3 hours later after Pathogenic E. coli infection and can occur in either individual piglets or whole litters (Bertschinger and Fairbrother, 1999). Severe cases result in dehydration, and mortality of up to 56% in piglets affected in the first days of life.

Pre-weaning piglet diarrhea

A grey or white diarrhea and become hairy and emaciated (Taylor, 2013). Pigs fed with milk replacer diets or poor quality creep feed may easily affected by this type of diarrhea.

Post-weaning colibacillosis

Watery yellow or grey/brown watery projectile diarrhea and dehydration. Blood and mucus are rarely present. Once pigs stop receiving maternal antibodies from their mother’s milk, they become susceptible to infections of E. coli acquired from the farm environment. The average mortality is up to 30-40% (Straw et al, 2006).

Metritis agalactia mastitis

Metritis agalactia mastitis (MMA), is considered the most common disease of the sow after farrowing. The reasons for MMA are multifactorial and are to be found in the areas of management and hygiene, feeding, water supply and animal specific factors such as body condition and age of the sows. The bacteria isolated from infected sows are always E. coli in dominant in the biofilm. Urinary tract infection now is thought of associated with E. coli colonization.


Escherichia coli is a part of the normal microflora of the human body, and also inhabits the intestinal tracts of other mammals. However, some E. coli pathotypes have acquired various putative virulence factors (VFs) from their environment.

Pathogenic E. coli strains are classified into six well-described categories (Kaper et al, 2004):

  1. Enteropathogenic E. coli (EPEC)
  2. Shiga toxin-producing E. coli (STEC)
  3. Enterotoxigenic E. coli (ETEC)
  4. Enteroinvasive E. coli (EIEC)
  5. Enteroaggregative E. coli (EAEC)
  6. Diffusely adherent E. coli (DAEC)

Enterotoxins produced by enterotoxigenic E. coli strains include heat-labile enterotoxin (LT), and /or heat-stable enterotoxins STa (STI) or STb (STII). These organisms also produce fimbrial adhesins that mediate the adherence of the bacterium to the mucosal surface. The fimbriae produced include K88, K99, 987P, F41 and F18. Some E. coli strains produce a Shiga toxin (Stx2e) and maybe cause edema disease in addition to post-weaning diarrhea.

Some E. coli strains produce no toxins, but efface the microvilli of the epithelial cells to which they attach (Taylor, 2013). Porcine attaching-effacing E. coli strains are known as enteropathogenic E. coli (EPEC). It is important to identify the virulence factors produced by ETEC or EPEC strains for many E. coli isolated from animals are nonpathogenic.nary tract infection now is thought of associated with E. coli colonization.

Control and Prevention

It has been suggested that the continuous use of antibiotics may contribute to a reservoir of drug-resistant bacteria which may be capable of transferring their resistance to pathogenic bacteria in both animals and humans (Han et al, 2007). As the incidence of carbapenem-resistant Enterobacteriaceae increased worldwide, polymyxins have been adopted as the last line of defense against Gram-negative bacterial infections (Liu et al, 2016). Resistance to polymyxins mainly depends on modification of lipopolysaccharide (LPS), which is often chromosomally mediated (Olaitan et al, 2014).

The principles of preventing an outbreak of colibacillosis revolve around hygiene and management factors aimed at reducing the buildup of pathogens and spread of infection , and establishing and maintaining piglet and sow immunity.

Piglets receive maternal antibodies specific to the E. coli in the immediate environment through colostrum, but only if the mother has been exposed to that environment. The degree of exposure to infection at birth and the immunity acquired through colostrum will determine whether clinical disease occurs (Taylor, 2013).

Antibiotics commonly used worldwide represent a relatively efficient way to eliminate infectious pathogens (Philips et al, 2004). Alternatives, such as organic acids or phytogenics, with antimicrobial effects have become increasingly important because of many countries banning the use of antibiotics to control bacterial infections in swine (Turner et al, 2001; Thacker, 2013).

Control and prevention factors

Adapted from Taylor, 2013


  • Animal keeper, stock person and veterinary hygiene
  • Move and re-bed farrowing huts on clean ground after every litter
  • Burn and remove old beds from paddocks
  • Move farrowing site annually and keep stocking rate low
  • Clean and disinfect equipment (especially important if pigs are housed), using appropriate detergents and disinfectants. Ensure that accommodation is dry before pigs are reintroduced


  • Help sows to create and maintain a level, dry farrowing bed
  • Add straw in small amounts frequently, in particular in wetter weather
  • Avoid gaps around the base of the hut that cause drafts
  • Carefully control sow feed levels, decreasing feed level by up to 0.5 – 1 kg per day four to five days pre-farrowing, to avoid udder edema
  • Ensure that piglets are kept at the correct temperature, as chilling is a trigger for the disease 


  • Expose in-pig gilts to farrowing beds and piglet feces
  • Foster piglets only after that have taken colostrum
  • Consider using E. coli vaccine for herds with persistent problems


  • Low protein diets
  • Organic acids or acidifiers
  • Zine oxide
  • Essential oils or phytogenic feed additives
  • Eucalyptus oil-medium chain fatty acids


Organic acids are used to combat pathogenic bacteria in animals and in animal feed since decades. Using acid combinations instead of single acids may be more beneficial due to a broader spectrum of activity (Namkung et al., 2003).

Organic acids are well known to improve growth performance and modulate intestinal microbiota of pigs (Piva et al., 2002). Organic acids lower the pH in feed and the gastrointestinal tract, creating unfavorable conditions for potentially harmful bacteria (Freitag, 2007). In their undissociated form, they can penetrate the bacterial cell and stop the bacterial growth or may even kill the bacterial cell (Stonerock, 2007).

Organic acid-based feed additives, with or without the use of antimicrobial growth promoters (AGPs), can help alleviate the negative effects of E. coli infection in pigs. Optimizing the activity of organic acids with phytochemicals and permeabilizing substances is a possibility to strengthen the activity of organic acids against Gram-negative bacteria like E. coli and Salmonella.

Addition of phytochemical cynnamaldehyde (CA) inhibits the so called FtsZ protein and plays a major role in the cell division of potentially harmful bacteria (Domadia et al., 2007). Under normal circumstances, FtsZ polymerises into filaments, which assemble at the place within the cell, where the cell division takes place. There they form into a polymeric structure known as the ‚Z-ring‘on the inner membrane in the middle of the cell, which is responsible for the cell‘s division. CA inhibits not only the formation of FtsZ into filaments, but also inhibits essential processes involved in the Z-ring formation and its function and thus the cell division. This results in a reduction of the bacterial load, within the gastrointestinal tract.

Figure 1. E. coli and Salmonella counts in negative and positive control and Biotronic® Top3 groups. Source: BIOMIN

The Biomin® Permeabilizing Complex in Biotronic® Top3 damages the outer membrane of Gram-negative bacteria thus boosting the synergistic effect of its components, the organic acids and the phytochemical. As shown in Figure 1E. coli counts in the ileum (log CFU/g) were lowest in the group fed the Biotronic® Top3 diet.


Bertschinger, H. U., & Fairbrother, J. M. (1999). Escherichia coli infections. In B. E. Straw, S. D’Allaire, W. L. Mengeling, & D. J. Taylor (Eds.), Diseases of swine (Eighth, p. Chapter 32). Ames, Iowa: Iowa State University Press.

Cheng D., Sun H., Xu J., Gao S. (2006). PCR detection of virulence factor genes in Escherichia coli isolates from weaned piglets with edema disease and/or diarrhea in China. Vet Microbiol. 115(4):320–329. Domadia P., Swarup S., Bhunia A., Sivaraman J., Dasgupta D. Inhibition of bacterial cell division protein FtsZ by cinnamaldehyde. Biochemical Pharmacology 74, 2007. P. 831–840.

Freitag M. Organic acid and salts promote performance and health in animal husbandry. In: Acidifiers in animal nutrition (Ed. Lückstädt C.). 2007. Nottingham University Press, Nottingham. P. 1–11.

Han W., Liu B., Cao B., Beutin L., Kruger U., Liu H., Li Y., Liu Y., Feng L., Wang L. (2007).DNA microarray-based identification of serogroups and virulence gene patterns of Escherichia coli isolates associated with porcine postweaning diarrhea and edema disease. Appl Environ Microbiol. 73 (12):4082–4090.

Kaper J.B., Nataro J.P., Mobley H.L.(2004) Pathogenic Escherichia coli. Nat Rev Microbiol. 2(2):123–40.

Liu Y.Y., Wang Y., Walsh T.R., Yi L.X., Zhang R., Spencer J., Doi Y., Tian G., Dong B.,Huang X., et al.(2016) Emergence of plasmid-mediated colistin resistance mechanism MCR-1 in animals and human beings in China: a microbiological and molecular biological study. Lancet Infect Dis. 16(2):161–169.

Namkung H., Li M., Yu H., Cottrill M., Gong J., de Lange C.F.M. Impact of feeding blends of organic acid or herbal extracts on growth performance, gut microflora and digestive function in newly weaned pigs. 2003. Proceedings of the 9th International Symposium on Digestive Physiology in Pigs, vol. 2, P.93–95.

Olaitan A.O., Morand S., Rolain J.M. (2014) Mechanisms of polymyxin resistance: acquired and intrinsic resistance in bacteria. Front Microbiol. 5:643.

Piva A., Casadei G., Biagi G. An organic acid blend can moderate swine intestinal fermentation and reduce microbial proteolysis. 2002. Canadian Journal of Animal Science 82, P.527-537.

Philips I, Casewell M, Cox T, de Groot B, Friis C, Jones R, et al. 2004. Does the use of antibiotics in food animals pose a risk to human health? A critical review of published data. J Antimicrob Chemother.53:28–52.

Stonerock R. Possibilities of salmonella control with the aid of acidifiers. In: Acidifiers in animal nutrition, (Ed. Lückstädt C.). 2007. Nottingham University Press, Nottingham. P.21–30

Straw, B. E., Zimmerman, J. J., D’Allaire, S., & Taylor, D. J. (2013). Diseases of Swine. John Wiley & Sons.

Taylor, D. J. (2013). Pig Diseases (9th ed.).

Turner JL, Pas S, Dritz SS, Minton JE. 2001. Review: Alternatives to conventional antimicrobials in swine diets. Prof Anim Sci. 25:217–243.

Thacker PA. (2013). Alternatives to antibiotics as growth promoters for use in swine production: A review. J Anim Sci Biotechnol. 4:35-47.

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