Escherichia coli

Identity

Preferred Scientific Name

• Escherichia coli Escherich, Th. 1885

International Common Names

• English: E. coli

Taxonomic Tree

• Domain: Bacteria
•     Phylum: Proteobacteria
•         Class: Gammaproteobacteria
•             Order: Enterobacteriales
•                 Family: Enterobacteriaceae
•                     Genus: Escherichia
•                         Species: Escherichia coli

Disease/s Table

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Pathogen Characteristics

E. coli is a Gram-negative, facultative anaerobic rod that is part of the normal intestinal flora and grows easily in most culture media. E. coli is classified into between 150 and 200 serotypes or serogroups based on somatic (O), capsular (K) and flagellar (H) antigens. Only strains of a restricted number of serogroups are pathogenic and are classified into categories or pathotypes based on the production of virulence factors. The most important categories in farm animals are enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), verotoxigenic E. coli (VTEC), and extraintestinal pathogenic E. coli (ExPEC). ExPEC consist of septicaemic E. coli (SEPEC) necrotoxic E. coli (NTEC), avian pathogenic E. coli (APEC), and nonsepticaemic extraintestinal E. coli. Certain O serogroups are associated with specific disease manifestations in each animal species.

ETEC

ETEC is the most common cause of E. coli diarrhoea in farm animals. These strains produce one or more fimbrial adhesions and enterotoxins. The most important fimbrial adhesins of ETEC in pigs are F4 (K88), F5 (K99), F6 (987P), F41 and F18 (F107). Three variants of F4(K88) have been described, ab, ac and ad. The most commonly encountered variant is ac. Two variants of F18, ab and ac, have been described. The variant F18ac is most commonly associated with ETEC. Isolates producing the F4 (K88) or F18 adhesin and certain isolates producing F6 demonstrate haemolysis on blood agar. All other ETEC from pigs are non-haemolytic. The most important fimbrial adhesins of ETEC in ruminants are F5 (K99), F41, and F17. Colonies of these isolates often tend to be more mucoid and rarely demonstrate haemolysis on blood agar. Enterotoxins produced by ETEC may be heat stable (STa or STb), or heat labile (LT), and an additional heat stable enterotoxin, enteroaggregative E. coli enterotoxin 1 (EAST1), has been recently observed on ETEC isolates from pigs (Yamamoto and Nakazawa, 1997). The most important pathotypes, that is, combinations of virulence factors, are listed in the tables below.

EPEC

EPEC are commonly associated with postweaning diarrhoea in pigs. Pig EPEC attaches intimately to the intestinal epithelial cell membrane by a bacterial outer membrane protein termed intimin, or EPEC attaching effacing, (eae) factor. eae interacts with the bacterial receptor, Tir, which is produced by the bacteria and translocated into the host cell membrane by bacterial Esp proteins. Pig EPEC associated with postweaning diarrhoea often belongs to serogroups O45 and O103.

VTEC

VTEC isolates from calves produce verotoxin (VT), also termed Shiga-like toxin (SLT) or Shiga-toxin (Stx). These isolates produce two different types of toxins, VT1 (Stx1) and VT2 (Stx2). They also attach intimately to the intestinal epithelial cell membrane by means of the intimin, or eae, factor as observed in EPEC. VTEC isolates from calves usually belong to serogroups O5, O26, O103, O111 and O118 (Fairbrother, 1999a).

VTEC from pigs mostly belong to serogroups O138, O139 and O141 . These isolates are haemolytic on blood agar (Gannon et al., 1988) and produce a variant of VT2, called VTe (Stx2e). They do not adhere intimately to the mucosal epithelium as observed for EPEC. On the other hand, many of these strains produce the fimbrial adhesin F18ab, previously known as F107. VTEC from pigs can also produce classical heat-stable (STa, STb) and heat-labile (LT) enterotoxins and the F4 fimbrial adhesin of ETEC (Mainil, 1999). 

ExPEC

SEPEC and nonsepticaemic extraintestinal E. coli usually possess the aerobactin iron acquisition system, resist the bactericidal effects of complement in serum and of phagocytosis, belong to a restricted number of serogroups (Blanco et al., 1996), and often produce the fimbrial adhesins F17 (Lintermans et al., 1988), CS31A (Girardeau et al., 1988) (Korth et al., 1991), or of the P (Brito et al., 1999), S, F165 (Maiti et al., 1994) (Harel et al., 1995) or AFA families (Wegmann). They often produce colicin V, cytotoxic necrotizing factors (CNF) 1 or 2, and cytolethal distending toxin (CDT) (Johnson and Lior, 1988).

APEC usually possess the aerobactin iron acquisition system, resist the bactericidal effects of complement in serum and of phagocytosis, belong to a restricted number of serogroups, mostly O1, O2, and O78, and often produce the fimbrial adhesin F1. Most APEC produce the temperature sensitive haemagglutinin (Tsh). APEC of serogroups O1 and O2 and certain non-typable isolates possess the K1 capsule. APEC, mostly of serogroups O1 and O18, may possess the P fimbrial adhesin F11.

Important categories, pathotypes, and serogroups of Escherichia coli causing disease in pigs.

Table showing important categories, pathotypes, and serogroups of Escherichia coli causing disease in cattle and sheep.

Table showing important categories, pathotypes, and serogroups of Escherichia coli causing disease in poultry.

Host Animals

Vectors and Intermediate Hosts

References

Blanco J, Blanco M, Mora A, Croas C, 1996. Escherichia coli associated with colisepticaemia in Spain. [Spanish]. Medicina Veterinaria, 13(12):680-686.

Blanco M, Blanco JE, Blanco J, Gonzalez EA, Alonso MP, Maas H, Jansen WH, 1996. Prevalence and characteristics of human and bovine verotoxigenic Escherichia coli strains isolated in Galicia (north-western Spain). European Journal of Epidemiology, 12(1):13-19; 38 ref.

Blanco M, Blanco JE, Blanco J, Gonzalez EA, Mora A, Prado C, Fernandez L, Rio M, Ramos J, Alonso MP, 1996. Prevalence and characteristics of Escherichia coli serotype O157:H7 and other verotoxin-producing E. coli in healthy cattle. Epidemiology and Infection, 117(2):251-257; 33 ref.

Brito BGde, Silva Leite Dda, Linhares REC, Vidotto MC, 1999. Virulence-associated factors of uropathogenic Escherichia coli strains isolated from pigs. Veterinary Microbiology, 65(2):123-132; 43 ref.

Fairbrother JM, 1999. Escherichia coli infections in farm animals. Howard JL, Smith RA, eds. Current Veterinary Therapy: Food Animal Practice. Philadelphia, USA: Saunders Company, 328-330.

Gannon VPJ, Gyles CL, Friendship RM, 1988. Characteristics of verotoxigenic Escherichia coli from pigs. Canadian Journal of Veterinary Research, 52(3):331-337; 34 ref.

Girardeau JP, Vartanian Mder, Ollier JL, Contrepois M, 1988. CS31A, a new K88-related fimbrial antigen on bovine enterotoxigenic and septicemic Escherichia coli strains. Infection and Immunity, 56(8):2180-2188; 48 ref.

Harel J, Jacques M, Fairbrother JM, Bossé M, Forget C, 1995. Cloning of determinants encoding F165 fimbriae from porcine septicaemic Escherichia coli confirms their identity as F1C fimbriae. Microbiology (Reading), 141(1):221-228; 54 ref.

Johnson WM, Lior H, 1988. A new heat-labile cytolethal distending toxin (CLDT) produced by Escherichia coli isolates from clinical material. Microb. Pathog., 4(2):103-113.

Korth MJ, Schneider RA, Moseley SL, 1991. An F41-K88-related genetic determinant of bovine septicemic Escherichia coli mediates expression of CS31A fimbriae and adherence to epithelial cells. Infection and Immunity, 59(7):2333-2340; 34 ref.

Lintermans PF, Pohl P, Bertels A, Charlier G, Vandekerckhove J, Damme Jvan, Schoup J, Schlicker C, Korhonen T, Greve Hde, Montagu Mvan, 1988. Characterization and purification of the F17 adhesin on the surface of bovine enteropathogenic and septicemic Escherichia coli.. American Journal of Veterinary Research, 49(11):1794-1799; 29 ref.

Mainil J, 1999. Shiga/Verocytotoxins and Shiga/verotoxigenic Escherichia coli in animals. Veterinary Research, 30(2/3):235-257; 145 ref.

Maiti SN, DesGroseillers L, Fairbrother JM, Harel J, 1994. Analysis of genes coding for the major and minor fimbrial subunits of the Prs-like fimbriae F165 of porcine septicemic Escherichia coli strain 4787. Microbial Pathogenesis, 16(1):15-25; 39 ref.

Yamamoto T, Nakazawa M, 1997. Detection and sequences of the enteroaggregative Escherichia coli heat-stable enterotoxin 1 gene in enterotoxigenic E. coli strains isolated from piglets and calves with diarrhea. Journal of Clinical Microbiology, 35(1):223-227; 39 ref.

Distribution Maps

• = Present, no further details
• = Evidence of pathogen
• = Widespread
• = Last reported
• = Localised
• = Presence unconfirmed
• = Confined and subject to quarantine
• = See regional map for distribution within the country
• = Occasional or few reports

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