VetBact logo


Swedish University of Agricultural Sciences

Veterinary bacteriology: information about important bacteria
Veterinary bacteriology

Species/Subspecies: Lawsonia intracellularis
Category: Motile
Etymology: Genus name: named after the Scottish veterinarian Gordon H.K. Lawson, who discovered the organism.
Species epithet: within the cell (intracellularly).
Significance:A very common infection that is spread all over the world.
  [Very important]   
Type Strain: 1482/89 = NCTC 12656.
Macromorphology (smell): Cannot be grown on solid media.
Micromorphology: Rods (0.3-0.4 x 1.5-2.0 µm), which are usually curved (vibroid-shaped). Darting motility by means of one polar flagellum has been observed in certain preparations.
Gram +/Gram -:G-
Metabolism: Microaerophilic
Fermentation of carbohydrates: Is not used for identification of Lawsonia spp. because it may be difficult to differentiate the metabolism between the bacterium and the host cell. Furthermore, many intracellular bacteria lack enzymes for carbohydrate metabolism because of evolutionary gene reduction.
Spec. Char.: Optimal growth temperature: 35-37°C. Celldependent and can be co-cultivated with intestinal epithelial cells.
HostsDiseaseClinical picture
Pigs, weaned pigs (6-15 weeks)Proliferative enteropathyCement-like chronic diarrhea and lost of weight. At autopsy, thickening of the wall, mucosal necrosis is seen, especially in the ileum. Proliferative intestinal adenomatosis
Pig (older slaughter pigs and adult animals)Proliferative haemorrhagic enteropathyAcute bloody diarrhea and sporadic deaths
Horse (foals)Equine proliferative enteropathy (EPE)Fever, lethargy, peripheral oedema, diarrhea, colic and weight loss. Thickening of the small intestinal wall
Genome Sequence:
Acc-noStrainSize (bp)Genome
NC_008011 PHE/MN1-00 1 457 619 1c + 3c 

16S rRNA Seq.:
Acc-noStrainNumber of NTOperon
U30147 (T) 1468 

Only one species has been described within the genus Lawsonia and it is also the only species within the class Deltaproteobacteria, which is of importance in veterinary medicine.
Comment:Obligately intracellular and therefore difficult to culture.
Reference(s): No. 11


New names of bacterial phyla

The taxonomic category phylum was previously not regulated by the International Code of Nomenclature of Prokaryotes (ICNP), but now this has changed and it was decided to revise the names of bacterial phyla. All phyla must be written in italics (which has been done on VetBact also before) and have the ending -ota.

Published 2023-03-01. Read more...
The taxonomy of chlamydias

Species within the family Chlamydiaceae were previously divided into two genera Chlamydia and Chlamydophila. However, the differences between these two genera were not that great and many research groups have not accepted this division. Therefore, the genus Chlamydophila has been returned to the genus Chlamydia and this change has now been incorporated in VetBact

Published 2023-03-15. Read more...

Recently Updated

Recent blog posts

Most recent comment

Swedish University of Agricultural Sciences