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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]   
Taxonomy:
Phylum
Proteobacteria
Class
Deltaproteobacteria
Order
Desulfovibroniales
Family
Desulfovibrionaceae 
Genus
Lawsonia
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
Catalase/Oxidase:
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.
Disease:
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 

Taxonomy/phylogeny:
 
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
Updated:2022-03-22

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During October 2021, an article was published by A. Oren och G.M. Garrity, in which new names are proposed for a number of taxa within the classification category phylum. This has resulted in many discussions in social media about whether it was really necessary to make these changes, which have created confusion among microbiologists and other professionals who come into contact with bacteriology.

Published 2022-09-28. Read more...

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