Spirochetes Flashcards
What 4 genera of Spirochetales are of veterinary importance?
- Treponema - T. paraluis-cuniculi, T. brennaborense
- Borrelia (tick IH) - B. burgdorferi, B. anserina
- Brachyspira (anaerobe) - B. hyodysenteriae
- Leptospira - L. interrogans
What are the 3 major structural characteristics of Spirochetales?
- slender, spiral (coiled), round, actively motile, “Gram-negative” —> too narrow to see on Gram stain
- 5-200 µm long and 0.1-3 µm wide
- outer sheath that acts as a unit membrane covering the protoplasmic cylinder
How do Spirochetales divide? What makes them actively motile? How does it move?
transverse fission
axial filament inserted through a proximal hook that runs along the protoplasmic cylinder and under the outer sheath —> helical path through rotation around the long axis and flexation
What respiration does Spirochetales do?
aerobic, microaerophilic, anaerobic
Since Spirochetales are difficult to see with a Gram stain, how are they observed?
- darkfield
- phase contrast
- immunofluorescence
- stains that make them thicker (silver impregnation)
Spirochetales structure:
What are 4 important characteristics of Borrelia?
- loosely coiled
- microaerophilic
- slow-growing
- highly motile
What is required for Borrelia growth? What techniques can be used to observe it?
long chain fatty acids, glucose, amino acids
- Gram-negative
- silver
- Giemsa
- darkfield
(up to 0.5 µm wide)
What is the etiology of Lyme Disease in the US? Europe? Asia?
Borrelia burgdorferi
B. garinii
B. afzelii
What 2 aspects make Borrelia burgdorferi difficult to culture?
- aerobic and fastidious
- low numbers of organisms present in infected animals
What acts as vectors to Borrelia burgdorferi causing Lyme Disease?
Ixodes ticks
- I. scapularis in the Northeast and Southeast
- I. pacificus in the Pacific areas
TICKS DO NOT TRANSMIT LYME DISEASE
What are the reservoir hosts of Borrelia burgdorferi?
small rodents, like white-footed mice, voles, chipmunks, and deer
- dogs may also serve as a host
When is Borrelia burgdorferi infection (Lyme Disease) most common? What elicits the inflammatory response? What is the pathogenesis like?
spring and fall
B. burgdorferi lipopolysacharide and a novel peptidoglycan
- large amounts of the peptidoglycan continue to be shed in joints, contributing to arthritis
- IL-1 releases, causing fever, rash, arthropathy, and antibody synthesis
- body’s defense can halt infection, or infection progresses due to persistence of the bacteria and/or autoimmune response
What are the 4 major virulence factors of Borrelia burgdorferi?
- phase variation of surface antigens
- motility
- resistance to host innate immunity
- suppression of host immune system**
Lyme disease is uncommon in horses, but still occurs. What are 8 clinical signs?
- cranky attitude
- back soreness
3, lameness - fever
- depression
- arthritis
- uveitis
- encephalitis
What happens with in utero Borrelia burgdorferi infection in horses? How many horses tend to be seropositive in endemic areas?
death, infection in foals by weaning
10% - asymptomatic, decline in performance
What are the 2 recommended treatments for Lyme Disease in horses? What is not recommended?
- Doxycycline, PO
- Tetracycline, IV
vaccination
What are the 8 possible clinical signs of Lyme Disease in dogs? How long does it typically take for these symptoms to appear?
- fever
- swollen lymph nodes
- inappetence
- lethargy
- sudden onset of lameness with pain or swelling in 2 or more joints (usually front limbs)
- CNS infection - cervical pain, seizures
- renal disease following chronic infection**
- myocarditis
2-5 months following bite
Lyme DIsease is rare in cattle. What are 5 clinical signs?
- lameness
- fever
- loss of appetite
- in utero infection = death in calves
- once case of arthritis, myocarditis, and pneumonia in Wisconsin
What are the 3 stages of infection of Borrelia burgdorferi in humans? What is characteristic of human infection?
- days to weeks after infection, a rash occurs around the area of the tick bite - host may contain infectious agent at this point
- weeks to months, infection becomes systemic with fever, fatigue, rash, arthritis, lymphadenopathy, CNS and PNS signs
- years, chronic arthritis and neurological symptoms, infection of heart muscle
wide range in severity of symptoms
What is imperative for Borrelia burgdoferi immunity? How do PMNs respond?
humoral - Spirochetes are killed by antibodies and complement
produce IL-8, IL-1, and TNF-α
What are the 3 major reasons that chronic infections with Borrelia burgdorferi can occur?
- suppression of host immunity
- autoimmune reaction to peptidoglycan
- bacteria cant be cultures, but evidence of bacterial DNA in certain tissue persists
What is imperative for Borrelia burgdorferi immunity? How do PMNs respond?
humoral - Spirochetes are killed by antibodies and complement
produce IL-8, IL-1, and TNF-α
How is Borrelia burgdorferi infection diagnosed?
- history, clinical signs
- direct staining of tissue and fluids (blood, CSF, joint fluid, urine)
- PCR
- isolation in modified Kelly medium
- SEROLOGY most reliable: IFA, ELISA, Western blot**
- IDEXX SNAP 3DX
What are 2 major public health concerns regarding Borellia burgdorferi?
- dogs may undergo aspymptomatic spirochtemia, thus acting as carriers
- anmals can be a source of infected ticks
What is the recommended treatment of Lyme Disease in dogs? Chronic cases? How can infection be avoided?
doxycycline*/tetracycline for at least 10-14 days, but 30 is recommended
ceftriazone (Rocephin) added to treatment + Clarithromycin or erythromycin
prevent exposure to ticks
What vaccines are the most useful for Lyme disease?
subunit vaccines —> directed for OspA
What does Borrelia theileri infection cause? What is characteristic of infection? What transmits them?
mild febrile anemia of horses, cattle, and sheep in South Africa and Australia
- AKA bovine borreliosis
spirochetemia and relapsing fever
hard ticks - Rhipicephalus spp.
What is the etiology of fowl spirochetosis? What transmits this? What species are susceptible?
Borrelia anserina
Argas persicus tick
chickens, ducks, turkeys, geese, pheasants, pigeons, canaries, game birds
- surviving birds recover in 2 weeks with long-lasting immunity
- exotic, unlikely in US
What are 5 clinical signs of fowl spirochetosis?
- acute septicemia
- depression
- progressive paresis and paralysis
- cyanosis
- greenish diarrhea with considerable urates
What are the 4 common findings in birds with fowl spirochetosis?
- inflammatory necrotic changes in parenchymal organs and the GI tract (bile-colored mucoid enteritis)
- splenomegaly
- hepatomegaly + mottling
- anemia
What are the 2 best ways to diagnose fowl spirochetosis? What vaccination works the best?
- demonstration of spirochete on blood smear with darkfield microscopy
- isolation in chicken or turkey embryo or medium containing rabbit tissue
bacterin (chicken embryo passage) - serotype-specific based on region
Direct staining, fowl spirochetosis:
- nucleated RBCs
- spirochetes
What does Borrelia coriaceae cause? How is it transmitted? How does it typically present?
epizootic bovine abortion, primarily in Western US
tick - Ornifthodorus coriacens
- asymptomatic infection
- abortion after repeated infection
What Borrelia species can cause relapsing fever in humans? How is it transmitted?
B. recurrentis
animal to human or human to human with lice vector
What Borrelia is a normal member of the mouth flora in humans? What can it cause upon infection?
B. vincenti
trench mouth
What are 2 symptoms of trench mouth in humans? Can it cause disease in other species?
(B. vincenti)
1. ulcerative, suppurative infection of gums and oral cavity (Vincent’s angina)
2. ulcerative tonsilitis and pharyngitis
may cause similar disease in dogs
What respiration does Treponema undergo? What is it associated with?
anaerobic
bovine papillomatous digital dermatitis (heel warts or hairy foot warts) in dairy cows
- moist, painful, strawberry-like lesions on skin, or chronic, raised, wart-like lesions
- ulceration of skin on the heel around the hoof can result in lameness
What novel Treponema has been isolated from hoof lesions? What are the best clinical symptoms and histopathology that can point toward this infection?
T. brennaborense
- strawberry lesion
- spirochetes found in deeper subcutaneous tissue
- polymicrobial infection with biofilm
Where is ovine footrot most commonly a problem? What 3 agents are the primary agents?
England, Australia, New Zealand
- Treponema brennaborense
- Fusobacterium necrophorum
- Dichelobacter nodosus
How is ovine footrot treated? Why is recurrence so common?
debridement + topical antibiotics (penicillin, ceftiofur) + zinc sulfate footbaths
contamination of the environment
What does Treponema paraluis-cuniculi cause? What is the most common symptom? How is it diagnosed?
rabbit syphilis or vent (genitalia) disease
vesicles and scabs on prepuce, vagina, and perineal regions
identification of spirochetes by darkfield from lesions
What does the treatment of human syphilis commonly cause?
Jarisch-Herxheimer reaction - fever, chills, rigors, nausea and vomiting, headache, tachycardia, hypotension, hyperventilation, flushing, myalgia, and exacerbation of skin lesions following antibiotic treatment of spirochete diseases
What does Brachyspira (Serpulina) hyodysenteriae cause?
acute and chronic swine dysentery in weaning pigs (growers and finishers)
- depression, sleepiness, lack of appetite, bloody diarrhea
What is required to culture Brachyspira hyodysenteriae?
OBLIGATE ANAEROBE that requires media supplemented with serum
What are the major reservoirs of Brachyspira hyodystenteriae?
- survival for months in manure
- asymptomatic pigs
What is the pathogenesis of Brachyspira hyodysenteriae?
- infects pigs following ingestion of infected fecal material
- organism survives the stomach’s acidity and passed through the small intestine to colonize the large intestine
Where is Brachyspira hyodysenteriae infection limited to? What aids in its colonization?
mucosa of the large intestine
other intestinal bacteria, like B. fragilis and F. necrophorum
What is the major virulence factor of Brachyspira hyodysenteriae? What does this allow? What other virulence factor is present?
highly motile due to a large number of flagella
penetrates mucous, colonizes colonic crypts, and invades goblet cells causing excessive mucus production and degeneration of enterocytes
hemolysin similar to streptolysin “S”
What species causes similar infections to Brachyspira hyodysenteriae? What does it cause?
B. pilosicoli
swine spirochetosis - nonfatal diarrhea and poor growth
What gross pathology is indicative of Brachyspira hyodysenteriae infection?
inflammation of the large bowel
- thickening of the mucosal folds with an intense inflammatory response resulting in the reddening of the mucosa, covered in mucous and fibrin
- later stages = severe ulcerative to necrotizing colitis
How can histopathology diagnose Brachyspira hyodysenteriae infection?
tissue silver impregnation staining showing Brachyspira in goblet cells
What is characteristic of Brachyspira hyodysenteriae infection in mild cases, acute cases, and in those with increased susceptibility?
MILD = mucoid diarrhea with flecks of blood (different from swine spirochetosis)
ACUTE = severe diarrhea
SUSCEPTIBLE = profuse bloody diarrhea with mucous
What is needed for immunity to Brachyspira hyodysenteriae?
antibodies to LPS (9 serotypes)
- some surface proteins/lipoproteins may phase vary to avoid host immunity
- bacterins
In what 4 ways can Brachyspira hyodysenteriae infection be controlled?
- quarantine new herd additions
- all-in-all-out management
- bacterins provide some protection and humoral immunity is protective
- B. hyodysenteriae has been isolated from many other animals, open floor channels between pens can spread disease
What is the best way to diagnose Brachyspira hyodysenteriae infection? How can they be cultured?
clinical signs and histopathology
- progressive filtration of GI extracts
- final filtrate can be cultured on blood agar under anaerobic conditions
- appears as a β-hemolytic film and can be seen on darkfield microscopy
(SEROLOGY not available or reliable)
What are 4 other species of Brachyspira that cause disease? What do they cause?
- B. pilosicoli - intestinal spirochetosis (zoonotic?)
- B. aalborgi
- B. intermedia
- B. alvinipulli
occur in the GI tracts of various animals and may cause chronic mucoid diarrhea and wasting or may be astymptomatic
What are the main symptoms of spirochete disease? How do they cause this?
diarrhea, wasting
attach to the intestinal wall and cause erosion of epithelial layers, hyperplasia, and depletion of goblet cells
