Leptospira Flashcards
What is the structure of Leptospira
- long, spiral, Gram-negative spirochete that usually have hooks at one or both ends
- winds around an axial filament (2 flagella) embedded between an outer envelope and cytoplasm
What respiration and fermentation does Leptospira undergo?
strict aerobe
uses only long-chain fatty acids as their carbon source
What 2 things are required to culture Leptospira? What is it extremely sensitive to?
- supplementation with 5-10% serum or albumin + B1, B12, and purines, like 5-flurocuracil
- grows best at 30 degrees C
heat, light, disinfectants
Leptospira, darkfield microscopy:
What are the 2 classifications of Leptospira based on virulence and antigenic differences?
- L. biflexa = non-pathogenic
- L. interrogans = pathogenic
What serovars of L. interrogans are present in the US and Canada?
(pathogenic)
L. pomona, L. hardjo, L. canicola, L. icterohemorrgaiae, L. grippotyphosa, L. bratislava
How is Leptospira classified based on genetics?
molecular studies have separated into genomospecies
- L. interrogans has 14 genomospecies
- L. biflexa has 6 genomospecies
What is the natural reservoir of Leptospira?
lumen of proximal convoluted tubules of the kidney
- may live in tubules for weeks to years, especially in rodents and excreted in urine
Where is Leptospira able to survive for extended periods of time after excretion in urine? In what 4 conditions can it not survive?
freshwater, soil, mud
- saltwate
- low pH
- low humidity
- low temperature
What are the 7 common serovars of Leptospira causing animal disease?
- L. kennewicki - horses
- L. bratislava - horses
- L. pomona - pigs, cattle, horses, skunks
- L. canicola - dogs, pigs
- L. icterohaemorrhagiae - dogs, cattle, pigs, rats
- L. hardjo - cattle
- L. grippotyphosa - dogs, wildlife (raccoons, skunks)
The virulence factors of Leptospira are not well-understood. What 6 substances/actions have been found in mutants?
- LPS - 10x less toxic than E. coli
- catalase
- axial filament - motility
- sphingomyelinase - hemolysin
- cytotoxins - protein, glycoprotein
- ability to invade cells
Most vertebrates are susceptible to Leptospira infection. What are 7 common diseases caused by infection?
- premature birth
- abortion
- infertility
- jaundice
- agalactia
- hemoglobinuria
- fever, inappetence, malaise
How does disease presentation with Leptospira compare in dogs and cats?
DOGS: acute hemorrhagic or chronic icteric and uremic syndromes
CATS: rarely gets clinical disease
What species of Leptospira most commonly causes acute/subacute infection in cattle? What production, clinical, and laboratory changes are evident?
L. pomona
- PRODUCTION: abnormal milk, agalactia
- CLINICAL: rash, intense muscle pain, GI signs, photophobia, encephalitis, acute nephritis, hemoglobinuria
- LAB: hemoglobinuria, increased BUN
What species of Leptospira causes chronic disease in cattle and swine? What 4 things does this cause? What causes this?
L. pomona
- nephritis
- uveitis
- encephalitis
- infertility
antigen-antibody complexes
What species of Leptospira commonly causes disease in calves? What 3 things does this cause?
L. hardjo
- abortion
- stillbirth
- weakness
What are the 3 forms of disease in dogs infected with Leptospira? What does this commonly result in? What 2 species cause this?
- hemorrhagic
- icteric
- uremic
- kidney failure, severe liver disease, shock
L. canicola and L. icterohaemorrhiagiae
How does Leptospira enter the host? How many cells are needed to cause infection?
enter through a scratch or mucous membrane
as few as 1-10 cells can cause fatal infection in susceptible hosts
What part of Leptospira is anti-phagocytic until specific antibodies are produced?
outer sheath
After Leptospira enters the bloodstream, where does it undergo initial replication? Where can they also infect and persist?
liver (4-20 days incubation)
- reproductive tract
- kidney
- brain
- eye
What 3 things happen when Leptospira enters tissues? What does this suggest?
- vasculitis in small vessels
- hemorrhage
- fluid leakage
organism (sphingomyelinase) or host-mediated (cytokine) toxic factors
What 4 things happen after the hematogenous spread of Leptospira to the lungs, brain, and kidneys?
- fulminating hepatic and renal disease, which can lead to death
- vascular damage leading to endothelial disruption via the release of TNF-α
- bile duct occlusion and jaundice
- nephritis
In which animals is a carrier state without clinical signs common with Leptospira disease? What causes this?
rodents
antibodies are able to clear leptospires from the blood and all organs except the kidneys, where they are able to multiply in the lumen of nephritic tubules
Where is Leptospira infection also able to happen in large animals? What does this result in?
uterus - can infect fetus and result in abortion or weak calves
What are the 4 ways of transmission of Leptospira?
- exposure to contaminated urine through wounds or moist skin
- transplacental transmission (abortion and stillbirths in cattle, horses, pigs)
- milk
- semen
(some species are adapted to specific animals - Norway rats and L. ictohaemorrhagiae)
Leptospira, silver impregnation stain:
Leptospira, carrier state:
What immunity is important against Leptospira? What is important to note about cows?
LPS antibodies
- early antibodies clear leptospires from blood by opsonization, but may persist in some tissues protected from antibodies (IgM, IgG serovar-specific antibodies)
cattle with antibodies to LPS may not be protected against another serovar —> may need IFNγ and a Th1 response
What are the 2 major ways Leptospira infections are controlled?
- multivalent bacterin - know your local serovars, no bacterin contains all 200+ serovars
- prevent exposure to infected urine
In what 5 ways is leptospirosis typically diagnosed?
- darkfield microscopy of urine, milk, water
- serology with a 4-fold change between acute and convalescent samples
- isolation - Fletcher’s, Ellinghausen’s, or Polysorbate liquid medium + 5-fluorouracil
- FA staining tissues
- histopathology of kidney, liver, and brain by silver impregnation staining
What is the best serological test to diagnose Leptospirosis? How does Leptospira grow on in liquid media?
microscopic agglutination test (MAT)
diffuse zone, then a (Dinger’s) ring near the tobe of the tube (strict aerobe)
What is the Ellinghausen-McCullough-Johnson-Harris medium used to isolate? What 7 ingredients are in it?
Leptospira
- various salts
- thiamine
- pyruvate
- glycerol
- bovine albumin
- tween 80
7 B12
What 2 things are important to note about antibiotic treatment of Leptospirosis?
- may not eliminate spirochetes from kidney
- penicilin and similar drugs may cause Jarisch-Herxheimer (endotoxic shock) reaction, so steroids may need to be added
How is Leptospirosis spread to humans? Who are most at risk? What disease does infection cause?
wound infection, mucosal and conjunctival exposure
persons swimming in contaminated water, especially children
Weil’s disease - acute febrile illness with jaundice, hemorrhages, pulmonary distress, splenomegaly, nephritis, and death
