Difference between revisions of "Spirochaetes"
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*Serology required for identification | *Serology required for identification | ||
+ | |||
+ | ===''Leptospira'' | ||
+ | |||
+ | *Motile, helical bacteria found in aquatic environments | ||
+ | *Require liquid media for culture | ||
+ | *Cause leptospirosis in all animals, which can range from mild urogenital tract infections to systemic diseases | ||
+ | *Organisms persist in kidney tubules or genital tract of carrier animals and are shed in urine | ||
+ | *Transmission via direct contact | ||
+ | *Serovars are fairly host-specific, causing mild disease in the maintenance host, with shedding in the urine | ||
+ | *Maintenance hosts may transmit the infection to incidental hosts, which are less susceptible to infection, but develop serious disease | ||
+ | |||
+ | *Pathogenesis and pathogenicity | ||
+ | **Depends on virulence of the serovar and susceptibility of the host | ||
+ | **Leptospires invade tissues through moist skin or via mucous membranes, aided by their motility | ||
+ | **Leptospires may invade via receptor-mediatied endocytosis | ||
+ | **They disseminate through the body via the blood stream | ||
+ | **Antibodies clear organisms from the blood stream after about 10 days of infection | ||
+ | **Organisms may persist in the renal tubules, uterus, eye or meninges | ||
+ | **Evade phagocytosis possibly via macrophage apoptosis | ||
+ | **Damage red blood cell membranes and endothelial and liver cells, leading to haemolytic anaemia, jaundice, haemoglobinuria and haemorrhage in acute leptospirosis | ||
+ | |||
+ | *Diagnosis | ||
+ | **Clinical signs and history of exposure | ||
+ | **Dark-field microscopy of urine may detect organisms | ||
+ | **Isolation from blood or urine by culture or animal inoculation | ||
+ | **Identificaiton or certain serovars using DNA probes and serology | ||
+ | **FLuorescent antibody technique for identification in tissues | ||
+ | **Silver impregnation | ||
+ | **Molecular techniques such as PCR | ||
+ | **Serology using microscopic agglutination test or ELISA | ||
+ | |||
+ | *Clinical infections | ||
+ | **Cattle and sheep | ||
+ | ***Cattle are maintenance hosts for ''L. borgpetersenii'' serovar ''hardjo'' | ||
+ | ***''L. interrogans'' serovar ''hardjo'' is host-adapted to cattle | ||
+ | ***Acute disease in susceptible heifers, with fever and agalactia of all quarters; abortion and stillbirth may occur | ||
+ | ***Diagnosed by rising antibody titre in paired serum samples | ||
+ | ***Infection in sheep may cause abortion and agalactia | ||
+ | ***Urinary excretion can be reduced by administering dihydrostreptomycin or amoxycillin | ||
+ | ***Incactivated vaccines are of questionable efficacy | ||
+ | ***Serovars ''pomona, grippotyphosa'' and ''icterohaemorrhagiae'' cause pyrexia, haemoglobinurea, jaundice, anorexia, uraemia due to renal damage and death in calves and lambs | ||
+ | |||
+ | **Horses | ||
+ | ***Clinical disease rare | ||
+ | ***May be maintenance host of serovar ''bratislava'', which causes abortion and stillbirth | ||
+ | ***Incidental hosts for serovar ''pomona'', suffering from abortion and renal disease | ||
+ | ***Chronic leptospirosis may cause an immune-mediated anterior uveitis | ||
+ | |||
+ | **Pigs | ||
+ | ***The rodent-adapted serovars ''icterohaemorrhagica'' and ''copenhagenii'' cause acute disease in pigs | ||
+ | ***Severe disease in young pigs | ||
+ | ***Serovar ''pomona'' is the host-adapted species, and may be shed in the urine | ||
+ | ***Infections may cause abortions and stillbirths | ||
+ | ***Pigs are maintenance hosts for serovars ''tarassovi'' and ''bratislava'', which may cause reproductive failure | ||
+ | |||
+ | **Dogs and cats | ||
+ | ***Serovars ''canicola'' and ''icterohaemorrhagica'' cause leptospirosis in dogs, but are vaccinated against | ||
+ | ***Serovars ''pomona'' and ''grippotyphosa'' are becoming important | ||
+ | ***The host-adapted serovar ''canicolar'' causes renal failure in puppies | ||
+ | |||
+ | |||
[[Brachyspira hyodysenteriae]] | [[Brachyspira hyodysenteriae]] | ||
[[Leptospira]] | [[Leptospira]] |
Revision as of 10:27, 31 December 2008
|
Overview
- Two families exist, Leptospiraceae and Spirochaetaceae
- Leptospiraceae include the pathogens of the genus Leptospira
- Spirochaetaceae include the pathogens of the genera Borrelia, Brachyspira and Treponema
- Many cause zoonotic infections
Characteristics
- Spiral or helical Gram-negative bacteria
- Motile organisms via endoflagella
- Poor survival in the environment and sensitive to dessication
- Stain poorly with Gram stain
- Most require specialised media for growth
- Serology required for identification
===Leptospira
- Motile, helical bacteria found in aquatic environments
- Require liquid media for culture
- Cause leptospirosis in all animals, which can range from mild urogenital tract infections to systemic diseases
- Organisms persist in kidney tubules or genital tract of carrier animals and are shed in urine
- Transmission via direct contact
- Serovars are fairly host-specific, causing mild disease in the maintenance host, with shedding in the urine
- Maintenance hosts may transmit the infection to incidental hosts, which are less susceptible to infection, but develop serious disease
- Pathogenesis and pathogenicity
- Depends on virulence of the serovar and susceptibility of the host
- Leptospires invade tissues through moist skin or via mucous membranes, aided by their motility
- Leptospires may invade via receptor-mediatied endocytosis
- They disseminate through the body via the blood stream
- Antibodies clear organisms from the blood stream after about 10 days of infection
- Organisms may persist in the renal tubules, uterus, eye or meninges
- Evade phagocytosis possibly via macrophage apoptosis
- Damage red blood cell membranes and endothelial and liver cells, leading to haemolytic anaemia, jaundice, haemoglobinuria and haemorrhage in acute leptospirosis
- Diagnosis
- Clinical signs and history of exposure
- Dark-field microscopy of urine may detect organisms
- Isolation from blood or urine by culture or animal inoculation
- Identificaiton or certain serovars using DNA probes and serology
- FLuorescent antibody technique for identification in tissues
- Silver impregnation
- Molecular techniques such as PCR
- Serology using microscopic agglutination test or ELISA
- Clinical infections
- Cattle and sheep
- Cattle are maintenance hosts for L. borgpetersenii serovar hardjo
- L. interrogans serovar hardjo is host-adapted to cattle
- Acute disease in susceptible heifers, with fever and agalactia of all quarters; abortion and stillbirth may occur
- Diagnosed by rising antibody titre in paired serum samples
- Infection in sheep may cause abortion and agalactia
- Urinary excretion can be reduced by administering dihydrostreptomycin or amoxycillin
- Incactivated vaccines are of questionable efficacy
- Serovars pomona, grippotyphosa and icterohaemorrhagiae cause pyrexia, haemoglobinurea, jaundice, anorexia, uraemia due to renal damage and death in calves and lambs
- Cattle and sheep
- Horses
- Clinical disease rare
- May be maintenance host of serovar bratislava, which causes abortion and stillbirth
- Incidental hosts for serovar pomona, suffering from abortion and renal disease
- Chronic leptospirosis may cause an immune-mediated anterior uveitis
- Horses
- Pigs
- The rodent-adapted serovars icterohaemorrhagica and copenhagenii cause acute disease in pigs
- Severe disease in young pigs
- Serovar pomona is the host-adapted species, and may be shed in the urine
- Infections may cause abortions and stillbirths
- Pigs are maintenance hosts for serovars tarassovi and bratislava, which may cause reproductive failure
- Pigs
- Dogs and cats
- Serovars canicola and icterohaemorrhagica cause leptospirosis in dogs, but are vaccinated against
- Serovars pomona and grippotyphosa are becoming important
- The host-adapted serovar canicolar causes renal failure in puppies
- Dogs and cats