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Brachyspira pilosicoli

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Brachyspira pilosicoli
Scientific classification Edit this classification
Domain: Bacteria
Phylum: Spirochaetota
Class: Spirochaetia
Order: Brachyspirales
Family: Brachyspiraceae
Genus: Brachyspira
Species:
B. pilosicoli
Binomial name
Brachyspira pilosicoli
Brandt and Ingvorsen, 1998" [1]
Synonyms[1]

Brachyspira pilosicoli is a Gram-negative, spiral-shaped, obligate anaerobe bacterium. It is a member of the Spirochaete family. The bacterium is loosely coiled and is 6–11 µm long. It has several flagellae, inserted at either pole of the cell, and a lipopolysaccharide cell wall. It causes intestinal spirochetosis in pigs, chickens, and people, and has been isolated from other species such as dogs, rodents and horses as well.[2] It causes zoonotic infection in humans, with infection thought to originate from dogs.

Lifecycle and pathogenesis

Infection of Brachyspira pilosicoli is acquired via the faecal-oral route. Once in the alimentary tract, the bacterium invades its target cells in the large intestine causing oedema, haemorrhage and the infiltration by inflammatory cells. The consequences of this are the sloughing of cells into the intestinal lumen, malabsorption and secretory diarrhea which could last up to two weeks.[2]

Diseases

Brachyspira pilosicoli is the cause of porcine intestinal spirochaetosis. The presence of the spirochaetes in grey-pink diarrhoea is diagnostic.

Zoonotic potential

Anaerobic host-associated spirochetes of the genus Brachyspira colonize the oral cavity, intestinal tract, and genital region of animals and humans.[3]  The principal species of veterinary significance is Brachyspira hyodysenteriae, the causative agent of swine dysentery.[4] However, other organisms in this group have been associated with disease in animals, including Brachyspira pilosicoli, a causative agent of porcine intestinal spirochaetosis.[4] Whereas most Brachyspira have a restricted host range, B. pilosicoli colonizes a variety of domestic animals, including pigs, chickens, and dogs, as well as wild birds, rodents, and humans.[5]  In particular, B. pilosicoli has been described as an important colonic pathogen of pigs and chickens, causing colitis and diarrhea resulting in depressed rates of growth and impaired production on farms where infections with B. pilosicoli may be endemic.[4][6]  In addition, B. pilosicoli is associated with clinical disease in human infections, thus possessing public health implications.[7]  

Interspecies transmission of B. pilosicoli has been demonstrated;[5] zoonotic transmission is highly likely, although it has not been conclusively shown.[7]  A number of studies that have isolated B. pilosicoli from fecal carriage have identified environmental factors that may be important in transmission.[8]  Specifically, the spirochete is passed in feces and may survive for prolonged periods in natural water systems such as lakes and ponds, from which it can be isolated.[9]  Therefore, it is presumed that infection occurs in humans via the oral route following exposure to infected fecal material of either human or animal origin.[9]  Colonization of the intestinal tract and consequential spirochaetosis, the presence of spirochetes forming a dense fringe or brush border on the colonic epithelium, is more commonly described.[9]  Incidences of blood-borne infections have been observed, however, cases of spirochetemia with B. pilosicoli are relatively uncommon.[10]  The incidence of intestinal colonization with B. pilosicoli and consequential spirochaetosis is associated with crowded and unhygienic conditions in developing countries.[8][11]  As a consequence of the spirochete’s ability to survive for long periods of time in stagnant water, there is conclusive evidence that suggests contaminated water sources may account for the high rates of intestinal carriage with B. pilosicoli found in developing communities.[5]  Studies investigating the prevalence of B. pilosicoli in human fecal carriage in Latin America demonstrate that human colonization with B. pilosicoli is significantly more common in individuals living in villages than in those living in an urban area.[8]  Specifically, if hygiene in a village is poor due to lack of modern sanitation and reliance on nearby streams as a sole source of water, fecal-oral transmission of B. pilosicoli is favoured.[8]  Similarly, the prevalence of B. pilosicoli in human fecal carriage is greater in crowded periurban areas that contain pigs and other animal species, where water is collected from shallow wells rather than having a supply of clean tap water as seen in urban areas.[11]  Opportunities for interspecies transmission of B. pilosicoli is more likely to occur in households where animals and humans live in close proximity, thus individuals working with intensively farmed pigs, chickens, or other farmed species may be at increased risk of exposure.[11]  In addition, it has been suggested that B. pilosicoli is able to survive meat processing and thus serves as a potential risk to consumers via contaminated raw meat.[6]  Largely as a consequence of the considerable genetic similarities between strains of B. pilosicoli infecting humans, swine, and poultry, the potential to adapt to various hosts exists.[6]

Human case reports of B. pilosicoli spirochaetosis have been described, suggesting that individuals colonized with B. pilosicoli may develop focal colitis and chronic diarrhoea, with abdominal pain, flatulence, gastrointestinal bleeding, rectal discharge, watery diarrhea, and pseudoappendicitis.[12]  Colonoscopic examination often reveals a normal-appearing mucosa.[5] However, edematous and erythematous mucosal changes have been reported.[5]  Following the apparition of any symptoms, intestinal spirochaetosis is confirmed by biopsy.[5]  Overall, human intestinal spirochaetosis with B. pilosicoli is relatively uncommon and there is debate in regards to its clinical significance as most cases are asymptomatic.[5]  Incidence of colonization is associated with crowded and unhygienic conditions in developing countries and in specific populations such as Australian Aborigines, as well as amongst homosexual males and HIV+ patients in western countries.[10]  Of those already colonized, spirochetemia has been observed in individuals with impaired immune defence or injury of the gastrointestinal mucosa.[13]  Further evidence of B. pilosicoli pathogenicity includes human cases of invasive hepatic infection and hepatitis in chronically ill or immunocompromised individuals where the spirochetemia is likely to have been secondary to the immunosuppression.[12]  These cases are likely examples of human infections of pathogenic B. pilosicoli from enteric commensal populations as a consequence of increased microorganism virulence or diminished host defences.[12]  It remains unclear as to what extent spirochetemia may contribute to clinical signs in these patients, although some patients have shown multiorgan failure.[10]  Nevertheless, spirochetemia also appears to be a relatively rare phenomenon in individuals where fecal carriage has been observed.[5]  

See also

References

  1. ^ a b c Brandt KK, Ingvorsen K (1998). "Validation of the publication of new names and new combinations previously effectively published outside the IJSB. List No. 64". Int. J. Syst. Bacteriol. 48: 327–8. doi:10.1099/00207713-48-1-327.
  2. ^ a b Hampson DJ (January 2018). "The Spirochete Brachyspira pilosicoli, Enteric Pathogen of Animals and Humans". Clinical Microbiology Reviews. 31 (1): e00087–17, /cmr/31/1/e00087–17.atom. doi:10.1128/CMR.00087-17. PMC 5740978. PMID 29187397.
  3. ^ Mappley, Luke J.; Black, Michael L.; AbuOun, Manal; Darby, Alistair C.; Woodward, Martin J.; Parkhill, Julian; Turner, A. Keith; Bellgard, Matthew I.; La, Tom; Phillips, Nyree D.; La Ragione, Roberto M. (2012-09-05). "Comparative genomics of Brachyspira pilosicoli strains: genome rearrangements, reductions and correlation of genetic compliment with phenotypic diversity". BMC Genomics. 13 (1): 454. doi:10.1186/1471-2164-13-454. ISSN 1471-2164. PMC 3532143. PMID 22947175.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  4. ^ a b c Casas, Vanessa; Rodríguez-Asiain, Arantza; Pinto-Llorente, Roberto; Vadillo, Santiago; Carrascal, Montserrat; Abian, Joaquin (2017). "Brachyspira hyodysenteriae and B. pilosicoli Proteins Recognized by Sera of Challenged Pigs". Frontiers in Microbiology. 8: 723. doi:10.3389/fmicb.2017.00723. ISSN 1664-302X. PMC 5415613. PMID 28522991.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  5. ^ a b c d e f g h Hampson, David J. (2017-11-29). "The Spirochete Brachyspira pilosicoli, Enteric Pathogen of Animals and Humans". Clinical Microbiology Reviews. 31 (1). doi:10.1128/CMR.00087-17. ISSN 0893-8512. PMC 5740978. PMID 29187397.
  6. ^ a b c Le Roy, Caroline I.; Mappley, Luke J.; La Ragione, Roberto M.; Woodward, Martin J.; Claus, Sandrine P. (2015-12-15). "Brachyspira pilosicoli-induced avian intestinal spirochaetosis". Microbial Ecology in Health and Disease. 26. doi:10.3402/mehd.v26.28853. ISSN 0891-060X. PMC 4683989. PMID 26679774.
  7. ^ a b Neo, Eugene; La, Tom; Phillips, Nyree Dale; Alikani, Mohammad Yousef; Hampson, David J (December 2013). "The pathogenic intestinal spirochaete Brachyspira pilosicoli forms a diverse recombinant species demonstrating some local clustering of related strains and potential for zoonotic spread". Gut Pathogens. 5 (1): 24. doi:10.1186/1757-4749-5-24. ISSN 1757-4749. PMC 3751851. PMID 23957888.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  8. ^ a b c d Trott, Darren J.; Mikosza, Andrew S. J.; Combs, Barry G.; Oxberry, Sophy L.; Hampson, David J. (1998). "Population genetic analysis of Serpulina pilosicoli and its molecular epidemiology in villages in the Eastern Highlands of Papua New Guinea". International Journal of Systematic and Evolutionary Microbiology. 48 (3): 659–668. doi:10.1099/00207713-48-3-659. ISSN 1466-5026. PMID 9734020.
  9. ^ a b c Hampson, David J. (2018-01-01). "The Spirochete Brachyspira pilosicoli, Enteric Pathogen of Animals and Humans". Clinical Microbiology Reviews. 31 (1). doi:10.1128/CMR.00087-17. ISSN 0893-8512. PMID 29187397. S2CID 21683878.
  10. ^ a b c Prim, Núria; Pericas, Roser; Español, Montse; Rivera, Alba; Mirelis, Beatriz; Coll, Pere (October 2011). "Bloodstream Infection Due to Brachyspira pilosicoli in a Patient with Multiorgan Failure▿". Journal of Clinical Microbiology. 49 (10): 3697–3699. doi:10.1128/JCM.00680-11. ISSN 0095-1137. PMC 3187341. PMID 21832021.
  11. ^ a b c Margawani, K. Rini; Robertson, Ian D.; Brooke, C. Josephine; Hampson, David J. (April 2004). "Prevalence, risk factors and molecular epidemiology of Brachyspira pilosicoli in humans on the island of Bali, Indonesia". Journal of Medical Microbiology. 53 (Pt 4): 325–332. doi:10.1099/jmm.0.05415-0. ISSN 0022-2615. PMID 15017290.
  12. ^ a b c Kanavaki, S.; Mantadakis, E.; Thomakos, N.; Pefanis, A.; Matsiota-Bernard, P.; Karabela, S.; Samonis, G. (2002-06-01). "Brachyspira (Serpulina) pilosicoli Spirochetemia in an Immunocompromised Patient". Infection. 30 (3): 175–177. doi:10.1007/s15010-002-2175-1. ISSN 1439-0973. PMID 12120947. S2CID 45197004.
  13. ^ Erlandson, Kristine Mace; Klingler, Edna Toubes (2005-06-15). "Intestinal spirochetosis: epidemiology, microbiology, and clinical significance". Clinical Microbiology Newsletter. 27 (12): 91–96. doi:10.1016/j.clinmicnews.2005.05.002. ISSN 0196-4399.

Further reading

  • Hirsh DC, Maclachan NJ, Walker RL (2004). Veterinary Microbiology (2nd ed.). London: Wiley-Blackwell. pp. 131–133.
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