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==Introduction==

==Introduction==

'''''Brachyspira pilosicoli''''' is a '''gram negative spiral shaped obligate anaerobe [[Bacteria|bacterium]]''', closely related to ''[[Brachyspira hyodysenteriae]]'', and one of the '''''[[Spirochaetes]]''''' family. The bacterium is loosely coiled and is 6-11µm long. It is only weakly haemolytic in contrast to ''B. hyodysenteriae.''

'''''Brachyspira pilosicoli''''' is a Gram-negative, spiral shaped bacterium. It is an anaerobic [[Spirochaetes|spirochaete]], closely related to ''[[Brachyspira hyodysenteriae]]''. The bacterium is loosely coiled and is 6-11µm long (see image). It is only weakly haemolytic in contrast to ''B. hyodysenteriae''.

The bacterium may have '''8-12 flagellae''', inserted at either pole of the cell and has a '''lipopolysaccharide cell wall''' which also acts as a virulence factor.

The bacterium may have '''8-12 internalised flagellae''', inserted at either pole of the cell between the inner and outer membranes. The outer membrane contains '''lipopolysaccharide''' (endotoxin). This pathogen can also cause '''zoonotic''' disease in people.  

 

This pathogen can also cause '''zoonotic disease''' in people.

==Lifecycle==

==Lifecycle==

Infection of ''B.pilosicoli'' is acquired via '''ingestion of contaminated faeces.''' Once in the Alimentary tract, the '''flagellae allow the bacterium to move through the mucus''' in the intestine and thus reach and invade its target cells in the large intestine. The organism remains '''infective for long periods in organic matter but is inactivated by sunlight.'''

Infection of ''B.pilosicoli'' is acquired via '''ingestion of contaminated faeces'''. Once in the Alimentary tract, the spiral rotating motion allows the bacterium to move through the mucus in the intestine and thus reach and invade its target cells in the large intestine. The organism remains '''infective for long periods in organic matter''' but is '''inactivated by sunlight'''.

The pathogen has been isolated from '''dogs, birds, mice and humans'''. Dogs are thought to be a source of infection for people.

The pathogen has been isolated from '''dogs, birds, mice and humans'''. Dogs are thought to be a source of infection for people.

==Pathogenesis==

==Diseases==

The '''attachment''' of ''B. pilosicoli'' to epithelial cells of colonic mucosa causes '''oedema, haemorrhage and leucocyte infiltration''', thus disrupting their function and leading to '''cell exfoliation and malabsorption'''. The invasion of goblet cells can also lead to '''secretory [[Diarrhoea|diarrhoea]].'''

''B. pilosicoli'' is the cause of '''[[Porcine Intestinal Spirochaetosis|porcine intestinal spirochaetosis]]''' which is a much milder disease than the [[Swine Dysentery|swine dysentery]] caused by ''[[Brachyspira hyodysenteriae]]''.

'''Toxins and proteins''' released by ''B. pilosicoli'' have '''haemolytic and cytotoxic effects'''. Its membranous '''LPS''' also contains an endotoxin (lipid A).

The presence of the spirochaetes in diarrhoeal faeces is not itself diagnostic because related, but non-pathogenic, species may be present.

==Diseases==

==Pathogenesis==

''B. pilosicoli'' is the cause of '''[[Porcine Intestinal Spirochaetosis|porcine intestinal spirochaetosis]]''' which is a much '''milder disease than the [[Swine Dysentery]] caused by [[Brachyspira hyodysenteriae]]'''.

The '''attachment''' of ''B. pilosicoli'' to epithelial cells of colonic mucosa causes oedema, shedding of epithelial cells, haemorrhage and leucocyte infiltration and leading to '''malabsorption'''. The invasion of goblet cells can also lead to '''secretory [[diarrhoea]]'''.

Presence of the spirochaetes in grey-pink diarrhoeal faeces is diagnostic.

'''Toxins and proteins''' released by B. pilosicoli have '''haemolytic and cytotoxic effects'''. Its membranous '''LPS''' also contains an endotoxin (lipid A).

{{Learning

{{Learning

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{{Andrew Rycroft

|date = January 4, 2012}}

[[Category:Brachyspira_and_Serpulina]]

[[Category:Brachyspira_and_Serpulina]]

[[Category:Pig Bacteria]]  

[[Category:Pig Bacteria]]  

[[Category:Zoonoses]]

[[Category:Zoonoses]]

[[Category:CABI Expert Review]]

[[Category:CABI Expert Review Completed]]